1977 MGB Supercharged Roadster!

Completely Restored & Modified Supercharged MGB!

Information contained on this website is for general information purposes!

 

What I expected from my MGB:

 To start this project I first had to decide what I expected from my MGB after completion. I

wanted a modern version of the British Classic MGB that was built for my driving habits,

having excellent tractability, very reliable, used mainly for city driving and cruising, easily

keeps up with modern vehicles, uses 87 octane fuel with good fuel economy, low to mid-

range torque and power, no need to rev over 5000 rpm's and with all the comforts of a

modern sports car. This made it easier in setting my goals.

 

Goals for my Restoration Project:

***Keep the 4 cylinder 1798cc engine making modification to compliment the installation

of a Moss M45 Supercharger with "emphasis placed on low to mid-range torque and power"

for increased throttle response and street performance.

***Change old parts with new or modern parts to enhance reliability, drivability, and

dependability. (Modernized MGB)

***Make exterior body modifications together with interior changes for a more modern and

sporty appearance.

***Attention to Detail...Do some Research...Take my time and Do it Right...

 

"The best tuned engines are the ones that have careful planning

 and the correct combination of subtle modifications!"

 

Research & Testing:

  Most engine rebuilds are built for high-end horsepower meaning higher rpm's, bigger

camshafts, higher compression ratio's, larger intake valves, larger exhaust system, ported

cylinder heads, higher idle rpm's, higher octane fuel and the torque curve being shifted

higher. This was the opposite of my needs of a street car with emphasis on low to mid-

range torque and power. My approach would surely be different which lead me into

researching cylinder heads, porting heads, valves, exhaust systems, camshafts, headers,

ignition systems, advance curves, and forced induction or supercharging. Research alone

was not enough and I did take the time to test different mechanical changes in order to

find the correct combination of modifications with the supercharger.

 

"High peak horsepower numbers, although very impressive, is not as important as the

"Area under the Power Curve" which ultimately determines drivability. People drive so

infrequently at the peak power range, that it is pretty much an insignificant number!"

 

Why I wanted Low to Mid-Range Torque & Power:

  Street performance engines are all about drivability, throttle response, and low to mid-

range torque and power. Throttle response is essential as it plays a major role in driving

pleasure. We spend the majority of our time idling and in the mid-range, meaning, we

need a broad, flat torque curve that develops peak power from 1500~4500 rpm. With this

engine, torque will be king in the lower rpm range for acceleration and then within the

power band it will spend the majority of its time. It will become a supercharged MGB that

is extremely dependable, and has excellent tractability for ease-of-driving.

 

"Street performance engines are all about drivability,

throttle response, and low to mid-range torque and power!"

 

Time to get Started:

  I always liked the rubber bumper MGB's, but also wondered how to make it look more

modern. This became what they call a "Restomod" and in this case to take a classic car,

update functional components with modern technology while not modifying the appearance

so much that it no longer resembles the classic car you started with. Looking at the early

MGB and MG-RV8 I decided on the following changes:

 

  This project started in May 2005 by completely stripping everything from my MGB, down

to the last nut and bolt, before taking it to a body and paint shop for body modifications,

sandblasting and painting. I always disliked the seams/beads all over the MGB and had

them all removed and body soldered, also used fiberglass over the body solder joints that

are under more stress. The top rear quarter panels were rounded to match the early type

rear tail light assembly. The side molding strips, and jacking points underneath the rocker

panels were removed. The hole for the antenna was covered up with sheet metal and

welded. I liked the smooth look of the early MGB without the side lamps and removed all 4

of them. The side mirrors needed a sportier look and installed Miata power side mirrors

with the Crack of Doom being reinforced. I now felt my MGB had a more modern and sporty

appearance.

 

  With body modification completed it was time to sandblast the entire car. Primer was

sprayed immediately and than the long job of body filler, lots of sanding, primer and

more sanding. I wanted a show room quality paint job and body preparation was the key.

The color I used was Metallic Gold, DuPont Choma Premier (Base and Clear Coat), 3 coats

of base, 3 coats of clear coat, wet sanded, buffed and polished. The exterior of this MGB is

smooth and flawless. When the sun shines on the Metallic Gold it glitters and sparkles.

 

All New Parts:

 With an empty body shell I installed all new parts and many modern components.

 

Modern Options on my MGB:

Power Windows	Power Mirrors (Miata)
Power Steering (Electric, Speed Sensitive)	Power Brakes (Servo Assisted)
Power Amplified Dash Antenna (Electronic)	Power Heater Control Valve (Electronic)
Moss M45 Supercharger with SU HIF44 Carburetor	Supercharger Heat Shield
5 Speed Ford Sierra T-9 Transmission w/Semi-Close Ratio	Hall Effect Sender w/Speedometer Cable
AAW Power Block and Wiring	96 amp GM/Delco CS-130 Alternator
High Torque Gear Reduction Starter	14" 10 Blade Electric Cooling Fan
Cibie 7" Headlamps "E-Code" with City Lights	100/90w Narva Halogen bulbs
VDO Gauges: Speedometer, Tachometer, Oil, Water, Fuel,	VDO Gauges: Outside Temp, Volt Meter, Vacuum/Boost
Security System with Led Flashing Light on Dash	Manual Override Cooling Fan Switch
Kenwood Head Unit - CD MP3 Tuner	Boston Acoustics 3 Ohm Pro-60 6.5" Component Speakers (2 Front & 2 Rear)
Rockford Fosgate 4 Channel Amp 75 RMS Watts per Channel	Permanently Mounted Battery Charger
Original 41427 45D4 Distributor w/Custom Curve	Pertronix LU-143 Electronic Ignition (45D)
MSD 6A Ignition Control	Cobalt Wires - NGK-6ES Spark Plugs
Rear Tubular Shock Conversion	Hood and Trunk Telescopic Gas Struts Lift
Special Tuning Front Air Dam	Carter P60504 In-Line Fuel Pump
K&N E-2400 Air Filter with Velocity Stack (Custom Made)	Basil's One Piece Aluminum Side Cover
Peco Header (Jet Hot Coated)	Peco Big Bore 2" Exhaust System
Fiero Seats with Custom Seat Covers	Modern Retractable Seatbelts
Deluxe Biscuit Interior Carpet	Biscuit Molded Trunk Set
Plush Floor Mats	MG Logo Cargo Mat
Rosewood 6 piece Dash Trim Kit	Billet Door Sill Plates "Roadster"
Billet Pedal Covers: Clutch, Brake, Accelerator Pedals	ABS Under-Dash Liner with Courtesy Led-Lights
Walnut & Chrome Shift Knob	Black Leather Miata Shift-Boot
MG-RV8 Moto-Lita 14" Eagle Rim Steering Wheel	Mohair Black Convertible Top MG-RV8 Style
Honda Side Markers/Turn Signal Repeaters	Super Bright LED Lights in Bumpers
Custom 3rd Brake Light	MG Logo Black Plush Tool Bag
Stainless Steel Front Grill	Stainless Steel Front/Rear License Plate Frames
High Flow Triple Chrome Stainless Steel Exhaust Tip	SAAB Space Saver Rim with T125/70D15 Tire
Mini-Lite Style Alloy 15" Wheels 195/65R15 Tires	MGB V8 Brake Pads with new Calibers
Lowered 1" Front Suspension 480 lb MGB GT V8 Spring Set	1" Lowering Block Kit for the Rear Suspension
Minor upgrades: Payen Gasket Set , ARP Fasteners, APT Lifter Set, Tuftrided Rocker Shaft, Blanking Sleeve, ...	Polyurethane Bushing and Pads, Dynamat, and many more minor upgrades...

 

Engine Choice:

  With the exterior completed it was time to make an engine decision. Do I install a V-6,

V-8, or add a Moss Supercharger? I felt nothing would be more interesting and appealing

than lifting the hood (bonnet) and seeing an Original 4 cylinder 1798cc MGB engine with a

Supercharger. With 80k on the engine it was a good time to rebuild it, and to rebuild it

with the thought of having a Supercharger. This would now become my "Personally built

Supercharger Engine".

New Engine Rebuild Parts:

Moss Eaton M45 Supercharger

12H4736 Port & Polished Cylinder Head

#88G303 Steel Billet Camshaft

Payen Head & Lower Gasket Sets

ARP Performance Fasteners (Head Kit-Rod Bolt Kit-Main Bearing Cap Bolt Studs)

Tuftrided Rocker Shaft

Main Bearing Set, Camshaft Bearings, Rod Bearing Set

Oil Pump, Oil Pressure Relief Valve and Spring

Duplex Timing Chain, Crankshaft Gear/Sprocket, Timing Chain Tensioner

16.2cc Standard Low Compression AE Hepolite Pistons with Rings and Pins

Push Rods with APT Lifter Set

Rear Main Seal, Thrust Washer Set, High Performance Manifold Gasket

 

Supercharger:

  The Moss Supercharger for the later 1975-1980 MGB uses the Eaton M45 positive roots-

type supercharger displacing 45 cu ins/rev or 750cc with a normal operating limit of 14,000

rpm. It's purpose is to increase air pressure and density in the intake manifold by pumping

more air into the engine. This concentrated charge of air results in a more powerful

combustion stroke in the engine's cylinder, resulting in improved performance by providing

more torque and horsepower, at lower engine rpm's, and yields instant throttle response.

 

  A supercharger than is essentially an air pump, it allows our small engine to take in a

similar volume of air and fuel as a larger engine. The only reason a larger engine makes

more power is that it converts a large volume of air and fuel into energy. A supercharger

achieves the same results, but only when under load or full throttle, not during normal

driving or cruising.

 

  Boost is the amount of additional pressure created by the supercharger. Example: If the

supercharger makes 7 psi of boost, the inlet charge is atmospheric pressure (14.7 psi) +7

psi for a total of 21.7 psi. Most normally aspirated engines barely achieve 70% volumetric

efficiency.

 

  The most important thing to remember is that while the supercharger is always spinning

and moving air, it is not always producing boost in the engine. What this means is that

even when the boost gauge reads "0" the engine is still achieving 100% cylinder filling, the

difference in drivability is experienced both on and off boost. When not on boost, you can

still feel an increase in torque and power during normal driving. The supercharger produces

boost under high load conditions which may include heavy acceleration, when going uphill,

passing another vehicle or under towing conditions. The majority of the time the MGB

supercharger will not be producing boost, instead offers the power you need on demand.

 

  The Supercharger comes with a 1.75" SU HIF44 carburetor that has been flow tested at

228 cfm for a power potential of 151 hp. It will not run out of carburetor until over 8000

rpm. Unless your MGB revs higher than 8000 rpm then this single 1.75" SU HIF-44 is more

than enough to do the job it was intended to do. It has a BCA needle, a 4.5 oz spring, and

85-90 wt oil in the dashpot.

 

  The safest compression ratio to use with the supercharger is 8.0:1. By raising your

compression ratio 1 point (8.1 to 9.1) is equivalent to 2 psi of boost. The more you raise

your compression ratio, the more chances of detonation with the supercharger.

 

  Replacement drive belts for the supercharger: Bando: 4PK1510 9/16", Gates: K040595

14mm 1525mm, Dayco: 5040595, Goodyear: 4040595

 

  When looking at buying a supercharger and rebuilding your engine don't make the

mistake of being concerned only with peak horsepower numbers. High peak horsepower

numbers, although very impressive, is not as important as the "Area under the Power

Curve" which ultimately determines drivability. People drive so infrequently at the peak

power range, that it is pretty much an insignificant number. The major concerns should be

dependability and tractability.

 

Changes made:

• Installed a Moss Supercharger: provides more torque and horsepower, at lower engine rpm's, and yields instant throttle response.

 

M45 or MP45!

  It is worth noting that the "Eaton M45", 3rd Generation Supercharger, used in the Moss

Supercharger Kit, was discontinued in 2008 and replaced by the "MP45" that has an internal

bypass, larger plenum, and increased supercharger speed from 14000 to 16000 rpm. This

led to a new manifold design, being moved forward along with the supercharger, allowing

more room for a slightly larger air filter, everything is similar to the M45, but different.

 

  I was curious and wanted to know if there were in fact any overall differences between

the M45 and the MP45. Here is something I found interesting:

Question: The 4th Generation MP45 (Eaton/Magnuson Products/JR) supercharger generates higher temperatures from 4000 rpm to 14000 rpm (practically the entire useful range of the supercharger) than the 3rd Generation M45. Sounds like a disimprovement to me.

Magnuson Products:

   According to the performance data on our Superchargers, an "M45" is probably more advantageous than an MP45 through the majority of the engine's operating range. For that reason, I'd consider looking at using the already-proven Jackson Racing System.

Best Regards, Sales Manager, Magnuson Products/Magna Charger

 

  So what did the above statement really mean? The Jackson Racing System mentioned is

the older Moss Motors Supercharger System, Moss owns Jackson Racing. In the chart below

one major difference is the Delta Temperature between the two units. The MP45 does in

fact generate higher temperatures throughout the entire useful range of the supercharger

compared to the M45, meaning the MP45 has a lower efficiency area (which means higher

intake temperatures and lower volumetric efficiency) than the M45. There are also charts

for inlet flow, power required to drive supercharger, and volumetric efficiency. All this data

supports the statement above that an M45 supercharger is more advantageous than the

4th generation MP45.

 

  The MP45 was designed for modern cars with fuel injection, electronic control unit (ECU),

and higher rpm's. They use power cards that take control of the fuel injection system and

also use air/water or air-to-air intercoolers. Luxuries we do not have with the MGB.

 

 Magnuson also did a test using the same engine and different superchargers to prove

a point, that bigger isn't always better. Results showed you should install the smallest

size supercharger that will provide you with your target boost level. It will be more

responsive (make boost sooner) and will require less horsepower to drive it.

 

  If you have the older Eaton M45 for your MGB you should be happy. The M45 is more

compatible with the MGB engine than MP45, making more torque and horsepower and with

less worries about denotation.

 

Delta T is the (Temperature Increase at Supercharger Outlet)!

 

Transmission & Gear Ratio's:

  With a supercharger I surely needed a better transmission and installed the Ford Sierra

T-9 Five Speed Transmission conversion kit. It is a lighter yet robust gearbox well capable

of handling more torque than the standard gearbox, is very quiet and smooth, with a tight

shifting gear radius.

MGB Ford Sierra T-9 Five Speed Conversion Kit!

 (English Ford Sierra/Merkur XR4Ti T-9 Transmission)

Gear Ratio's:	62-67	68-74	75-76	77-80	T-9 Ford Standard	T-9 Semi-Close Ratio
1st Gear	3.63	3.44	3.03	3.33	3.65	3.36
2nd gear	2.21	2.16	2.16	2.16	1.97	1.81
3rd Gear	1.37	1.38	1.38	1.38	1.37	1.26
4th Gear	1.00	1.00	1.00	1.00	1.00	1.00
5th Gear/OD		.82	.82	.82	.82	.825    Reverse:  3.365

 Gear Ratio's for all MGB's, T-9 Ford Standard, & T-9 Semi-Close Ratio!

 

  The Ford Type 9 gearbox is Fords first 5 speed rear wheel drive gearbox. Based on the 4

speed Type E gearbox it is a popular 5 speed conversion for the MGB and for many other

applications.

 

  The Ford Sierra 4 cylinder T-9 transmission has standard gear ratios of: 1st: 3.65, 2nd:

1.97, 3rd: 1.37, 4th: 1.0, 5th: .82

 

  The 2.8L V6 Ford Sierra and the 2.3l Turbocharged I4 Merkur XR4Ti T-9 transmission has

standard gear ratios of: 1st: 3.36, 2nd: 1.81, 3rd: 1.26, 4th: 1.0, and 5th: .825

 

  Even though both of these gear ratios are standard gear ratios, same T-9 transmission

only having different gear ratios, but when it comes to the MGB conversion they will list

the 2.8L V6 / 2.3L Turbocharged as either being a Close, Semi-Close, 2.8 Sport, or Closer

ratio when used for the MGB. I can only assume they needed to call it something as an

alternative to the standard Ford Sierra gear ratio. For the MGB, I feel the best terminology

is to call it a "Semi-Close" gear ratio because it is not a "Close Ratio".

 

  You can purchase a T-9 "Close Ratio" gear set that has a much higher 1st gear of either

2.91, 2.71, or 2.48, with the other gears more closely spaced. These ratio's will cause you

to shift frequently, better for use on the track than on the street.

 

  I felt the T-9 Standard gear ratio is great for a stock MGB, having almost the same gear

ratios as the early 62-67 MGB. When you add performance, like a supercharger or other

engine modifications, the "Semi-Close" gear ratio becomes a much better choice for the

street. The T-9 standard ratio has a very low 1st gear of 3.65 compared to the Semi-Close

1st gear of 3.36 gear ratio. The T-9 standard ratio 2nd gear of 1.97 means you would need

to change into 3rd gear to achieve 60 mph whereas the Semi-Close 2nd gear of 1.81, being

more performance orientated, allows you to easily reach 60 mph in 2nd gear. The T-9

Standard 3rd gear of 1.37 is basically the same as the OEM 3rd gear ratio with no real

benefit. The Semi-Close 3rd gear of 1.26, also a higher gear, works flawlessly with the

supercharged MGB and will accelerate quite easily. Both ratios have the same 4th gear of

1.0. If you look at these ratios you might feel as I did that the Semi-Close is well suited

for a supercharged MGB with less shifting on the street.

 

  An engine that puts out a small amount of torque will generally be better off with a

lower gear ratio (numerically higher), like the standard 1st gear ratio of 3.65. An engine

that puts out a lot of torque, as a supercharged MGB, will accelerate quite well with a

higher gear ratio (numerically lower), like the semi-close 1st gear ratio of 3.36. Another

area to consider is that tire size also affects the effective gear ratio. A taller tire will have

the effect of going to a higher gear. I changed from the OEM 14" tire to a 195/65R15 which

is taller. Having lower gears ( T-9 Standard Gear Ratio) counteracts the taller tires to a

degree. Having a higher ratio (T-9 Semi-Close Gear Ratio) also increases the attainability

of higher speeds at lower rpm's, giving greater top speed, lessens wear on the engine, and

improves fuel economy.

Approximate Speed/RPM Table:

Tire Size: 195/65R15  Rims: 5.5"

Tire Diameter:  24.98"

MGB Bolt Pattern: 4 x 4.5 or 4 x 114.3mm

Final Drive Ratio:  3.909

Speed Ratio: Ford T-9 Semi-Close Ratio compared to MGB 68-74 (OEM Tire 155SR14):

Ford T-9 Close Ratio	1st: 3.36	2nd: 1.81	3rd: 1.26	4th: 1.00	5th: 0.825	MGB 68-74	1st: 3.44	2nd: 2.16	3rd: 1.38	4th: 1.00	OD: 0.82
0      rpm	0	0	0	0	0	0     rpm	0	0	0	0	0
500   rpm	3	5	8	10	12	500  rpm	3	4	6	9	11
1000 rpm	6	11	15	19	23	1000 rpm	5	8	13	18	22
1500 rpm	8	16	23	29	35	1500 rpm	8	12	19	27	33
2000 rpm	11	21	30	38	46	2000 rpm	10	17	26	36	44
2500 rpm	14	26	38	48	58	2500 rpm	13	21	32	45	55
3000 rpm	17	32	45	57	69	3000 rpm	16	25	39	54	65
3500 rpm	20	37	53	67	81	3500 rpm	18	29	45	63	76
4000 rpm	23	42	60	76	92	4000 rpm	21	33	52	72	87
4500 rpm	25	47	68	86	104	4500 rpm	23	37	58	81	98
5000 rpm	28	53	75	95	115	5000 rpm	26	41	65	90	109
5500 Redline Rpm	31	58	83	105	127	5500 Redline Rpm	29	46	71	98	120
5700 0-60 mph		60
6000 Safe Max RPM	34	63	91	114	------	6000 Safe Max Rpm	31	50	78	107	-----
6200 Valve Float	35	65	94	118	------	6200 Valve Float	32	51	80	111	-----

Note: The T-9 semi-close ratio achieves higher speeds at lower rpm's. Confirmed by G-Tech results it will reach 60 mph in 2nd gear at 5700 rpm's. 6200 rpm valve float is with the single valve spring setup.

Technical Data Ford T-9 5 Speed!

The 5 speed Ford Sierra propeller shaft is manufactured to specification:

Torque rating (Short Duration): 570Nm Maximum (422 ft.lb.)

RPM rating of propeller: 7000 rpm Maximum

(This corresponds to an engine speed of 5740 rpm in 5th gear (ratio .82:1) or an engine speed of 7000 rpm in 4th gear (ratio 1:1)

Length: 30½" Speedo Output: 18"-24" Center of lever opening: 28¾"

Underside mounting point: 21" Weight: 86 lbs.

Oil: Castrol SAE 75w90 Full-Synthetic Gear Oil

 

Note: I used a VDO Speedometer Gauge. A Hall Effect Sender (pictured above) must be attached to the speedometer cable in order for the gauge to work properly. I sent my cable to Speedometer Service Company who cut the cable and installed the Sensor to the end of the cable. Total length after completion was 18".

 

Changes made:

• Installed a Ford T-9 Five Speed with Semi-Close Gear Ratio: More suitable for performance applications, achieves higher speeds at lower rpm's, lessens engine wear, and improves fuel economy.

 

Supercharger Camshaft:

  I wanted to change the 1977 MGB camshaft 1156, the so called smog cam, because it

would not benefit the supercharger. There are many options to choose from, even specially

built supercharger camshafts, but when looking over dyno results they all seem to push for

high-end horsepower, higher rpm's, and the torque curve being pushed up. My goal was for

low to mid-range torque and power. I decided on installing the standard Camshaft 88G303

used on all MGB's in the UK from 1965-1980, it's a superb design that is unequalled in it's

ability to make good horsepower yet still retains excellent tractability.

 

Single Camshaft Sprocket Advanced 4°, "Not True":

  The 18G series engine from 1965-1971 used the duplex timing chain and camshaft

sprocket, recommended for high performance engines, added strength. In October of 1972,

the duplex timing chain was replaced by the single timing chain, on all 18V series engines,

including the rubber bumper MGB's in the UK. If you have a chance, read "How to Power

Tune MGB 4 Cylinder Engines," by Peter Burgess. In the book it shows all UK home market

specifications for cam timing. He states: "The 18V engine used the same camshaft as its

predecessors but its timing was "4 Degrees" more advanced, which didn't help the engine

rev well or make good top end power, offering instead low rpm torque and cleaner

emissions." It was the new cylinder head with 1.625 intake valves that raised high-end

power.

 

  There is a lot of misinformation about the single sprocket being advanced 4°, or the

camshaft, both are not true. We know that from 1965-1980 the same 88G303 camshaft

was used on all UK home market MGB's. The 18G series engines from 1965-1971 had cam

timing set at 110°, retarded at 2.5° ATDC. The 18V series from 1972-1974 including the UK

18V Rubber Bumper from 1975-1980 all had cam timing set at 106°, advanced 1.5° BTDC.

Add it up: 2.5° ATDC + 1.5° BTDC = 4° difference and they all use the same camshaft.

Photo above shows the keyway change with Sprocket teeth aligned.

 

  Here is the logical answer: The duplex sprocket "Keyway was Retarded 2.5°" and part

of the sprockets design, retarding the cam timing and providing more high-end horsepower.

Likewise, the single sprocket "Keyway was Advanced 1.5°" and part of the sprockets

design, advancing the cam timing and providing low rpm torque. Simple degree changes in

each of the camshaft sprocket "Keyways" to easily retard or advance cam timing. If there

was any other keyway degree change of the duplex camshaft sprocket, the cam timing

would not be 110°, likewise, any other keyway degree change of the single camshaft

sprocket, the cam timing would not be at 106°. If the single sprocket was advanced 4° the

cam timing would be 103.5 Intake and 111.5 Exhaust. This proves that keyway change was

in each of the sprockets design.

Below charts shows the 4° change in Single & Duplex Sprockets:

88G303 Camshaft Duration & Lift Specification for 18G Engines 1965-1971!

Duplex Timing Chain & Sprocket!

Intake:  16 / 56     Exhaust:  51 / 21    Cam Lift: 0.250"

Duration: 252°   Overlap: 37°   Intake: 110°   Exhaust: 105°   LSA: 107.5°

18G engines, 110°, Four degrees retarded from 18V engines!

The camshaft timing was retarded 2.5° ATDC, keyway retarded -2.5°!

 

88G303 "Centerline" Camshaft Duration & Lift Specification!

Intake:  18.5 / 53.5     Exhaust:  53.5 / 18.5

Duration: 252°   Overlap: 37°   Intake: 107.5°   Exhaust: 107.5°   LSA: 107.5°

Keyway: 0° Centerline

 

88G303 Camshaft Duration & Lift Specification for 18V Engines 1972-1974!

Also used on the UK Rubber Bumper MGB 1975-1980!

Single Timing Chain and Sprocket!

Intake:  20 / 52     Exhaust:  55 / 17     Cam Lift: 0.250"

Duration: 252°   Overlap: 37°   Intake: 106°   Exhaust: 109°   LSA: 107.5°

18V engines, 106°, Four degrees advanced from 18G series engines!

The camshaft timing was advanced 1.5° BTDC, keyway advanced +1.5°!

 

If the 88G303 Camshaft with Single Sprocket keyway advanced 4° from centerline!

Intake:  22.5 / 49.5     Exhaust:  57.5 / 14.5

Duration: 252°   Overlap: 37°   Intake: 103.5°   Exhaust: 111.5°   LSA: 107.5°

This shows the keyway "Cannot" be advanced 4°!

 

Advancing Camshaft:

  There are two easy ways to change the characteristics of your camshaft. Advancing will

move the power band down, more low-end torque. Retarding will move the power band up

a few hundred rpm, more high-end power. The second way is to change the valve lash,

tightening will increase top end power, loosening will increase bottom end power.

 

Advancing Cam Timing!	Retarding Cam Timing!
Begins intake event sooner	Delays intake event
Opens intake valve sooner	Opens intake valve later
Builds more low-end torque	Build more high-end power
Decreases piston-to-intake valve clearance	Increases piston-to intake valve clearance
Increases piston-to-exhaust valve clearance	Decreases piston-to-exhaust valve clearance
Loosen Valve Lash!	Tighten Valve Lash!
Increases Bottom End Power	Increases Top End Power

 

  Why is cam timing so important? Because it affects engine performance. For the engine

to run its best, it needs accurate cam timing. As a rule for the MGB, advancing cam timing

from the original ground centerline ("Straight Up" 107.5°) 2 to 4 degrees helps low-speed

torque and throttle response with little sacrifice in the higher rpm power. Retarding the

cam improves performance at high rpm at the expense of low speed torque which is not

what you want in a stock or street performance engine.

 

"Ask yourself how often you actually drive your MGB in the higher power band."

"Most MGB owners shift at 3500 rpm's, hardly ever taking it to 5000 rpm's."

"The 88G303 camshaft is all you need in a Stock or Supercharged MGB!"

 

My 88G303 Camshaft Setup with Duplex Timing Chain and Sprocket!

 

  When I installed the duplex timing chain and sprocket with the 88G303 camshaft on my

MGB, the cam timing was 110°. I used the book method with the dimples adjacent to each

other, the crankshaft keyway at TDC, and the camshaft keyway at two o'clock. I also used

a dial indicator and degree wheel to double check cam timing. I wanted to advance my cam

timing to 105°, 2.5° BTDC. I used a 5° offset camshaft key to advance the timing from

110° to 105°. The earlier intake and exhaust opening events will help the supercharger

breathe more air into and out of the engine which is recommended for increased low rpm

torque. Opening the intake valve sooner and having a greater amount of valve opening at

TDC, the intake pressure can purge the residual exhaust from the combustion chamber,

thus providing better filling of the cylinders.

 

 There are a lot of supercharges MGB's using this setup with timing set at 106° using a 4°

offset key with the duplex timing chain and sprocket or with the single sprocket and chain

timed normally at 106°. The reason I set mine at 105° with a 5° offset camshaft key is

because over time the timing chain does stretch and it will retard the camshaft timing.

When this does happen it will most likely end up at 106°.

 

  There is more than enough information on camshafts to use with the supercharger and it

simply comes down to every increase in camshaft duration moves the engine's power band

higher on the rpm range. Dyno results have shown that the standard 88G303 camshaft

makes excellent torque and horsepower with the supercharger. This is the only camshaft I

would use for keeping low to mid-range torque and power while maintaining tractability.

 

Camshaft Timing I used:

This is the exact opposite of the 18G series engine camshaft timing at 110°.

Excellent for Low and Mid Range Torque!

 Slight Loss of High RPM Power!

Steel Billet 88G303 Camshaft! (Moss 451-335)

88G303 Camshaft with Duplex Timing Chain and Sprocket,  5° offset key!

Intake: 21 / 51     Exhaust:  56 / 16    Cam Lift: 0.250"

Duration: 252°   Overlap: 37°   Intake: 105°   Exhaust: 110°   LSA: 107.5°

The camshaft timing is advanced 2.5° BTDC

Changes made:

• Changed CAM-1156 (1975-1980) to 88G303 camshaft (1965-1980): Provides good horsepower and retains excellent tractability.

• Changed single chain and sprocket to duplex and sprocket: Recommended for high performance engines, added strength.

• Advanced timing 2.5°: Increases low speed torque and throttle response.

 

Cylinder Heads:

  The 1975-1980 MGB's had cylinder heads fitted with smaller intake valves, back to the

1.5625" (39.8mm) diameter of the early 1962-1971 MGB's. From 1972-1974 the intake

valve were enlarged to 1.625" (41.3mm). What did this change actually mean? With bigger

intake valves it is reasonable to expect more power, but this turns out not to be the case.

Both the smaller intake valve and the bigger intake valve engines produced the same

torque and horsepower! The larger 1.625" intake valves provided more high end power

while the smaller 1.5625" valves provided more low to mid-range torque and power. For the

street, smaller valves will have an advantage in the mid-range torque as they keep the gas

velocity higher and this is exactly what I wanted.

 

12H4736 Cylinder Head:

  The MGB engine used 5 basic cylinder head designs. I wanted a cylinder head that would

benefit the supercharger. After researching the different cylinder heads I decided on the

4th design of cylinder heads. This was a slightly modified version of the 12H4736 cylinder

head first introduced on the Austin/Morris Marina, was used on post 1974 UK/European

market MGB's, and also as a replacement cylinder head in the United States.

 

  The U.S. Market 12H4736 is a "lead free" cylinder head and was induction hardened to

withstand higher combustion temperatures of lead-free fuel. This complex process applied

only to the U.S. (NA) market cylinder heads.

Note: North American cylinder heads post December 1974 were lead free tolerant and did have induction hardened valve seats. The process involved 1% tin being added to the molten iron before casting. This led to an issue where the iron touched the mold suffered a changed molecular structure and so additional depth of material was used in modified molds which was then machined off before the induction hardening process was applied to the valve seat area, all valve seats.

 

 It has an improved intake port design that produced a 4% increase in flow at maximum

valve lift. It used 1.5625" intake valves and 1.343" exhaust valves with a more efficient

"Open" Kidney-Shaped combustion chambers featuring a larger squish area, chamber height

of .375" with a volume of 39cc. The rear rocker shaft pedestal had an offset oil feed in

order to accommodate the redesigned cooling passages that assisted in preventing

overheating of the rear cylinder. These large coolant ports provided a greater service area

to assist in dealing with higher combustion temperatures that resulted in efforts to reduce

emissions. It has air injection ports and water choke outlet at the rear of the cylinder

head. When compared to other MGB cylinder heads the outer shaping was revised having a

much smoother looking appearance. The Patent Number 565394 located by the thermostat

housing was removed and marked inside the cylinder head. I felt this cylinder head has

that little extra I was looking for with the supercharger.

 

  This cylinder head also used "Single Valve Springs" and felt they were sufficient for my

cylinder head. They at suitable for cams up to 400 thou valve lift, allowing 6200 rpm before

valve float/crash. Double Valve Springs are helpful at higher rpm's, but on the street they

just add drag and wear to the camshaft. With my setup and no plans to really go over 5000

rpm's I had no reason to add double springs to the valves.

 

Work done on my 12H4736 Cylinder Head:

* Cleaned and Glass-bead blasted!

* Magnafluxed & Pressure Tested!

* Ported & Polished!

* 3 Angle Valves and Seats!

* Manganese-Bronze Intake & Exhaust Guides!

* Guides Reamed and Honed!

* Stellite Exhaust Seat Inserts!

* New 1.56" Intake Valves and 1.343" Stellite Exhaust Valves!

* Removed Air Injector Tubes!

* Air Injection Plugs: 7/16"-20-3/4" Bolts Cut Off Flush! Smooth Appearance!

* Deck Surface Milled .020" True!

* New Single Valve Springs!

* Fel-Pro SS70373 Valve Stem Seals (71-74 Chevrolet)

* New Intake Manifold Studs!

* High Performance Manifold Gasket!

* Gloss Black Color!

Changes made:

• 12H4736 Cylinder Head: Improved intake port design, redesigned cooling passages, 1.56" intake valves that will maintain low to mid-range torque and power.

• 3 Angle Valves and Seats: Improves air flow, torque and horsepower.

• Single Valve Springs: Reduces street drag and wear on the camshaft.

• Deck Milled .020": Raises compression slightly, more torque and power.

 

Checking My Compression Ratio:

   In order to check compression ratio's you need some numbers:

• Cylinder Head Depth Height: My cylinder head was milled .020" with a depth height of 3.105" (3 7/64") from the original 3.125" (3 8/64"). Cylinder Head Thickness.

• Deck Height: Deck height with standard pistons measured .030" from the flat top of the piston and .034" going down from the flat top edge into the bore. You can use either measurement as it will not make much of a difference. I used the middle of these measurements for .032" deck height.

• Combustion Chambers: Each of my chambers measured exactly 36.8 cc.

• Payen Head Gasket: Measures .043" Compressed.

• Compression Ratio: The chart below has my results:

I have a Compression Ratio of 8.157:1, Slightly above 8.0:1, but still ok!

Compression Test Results!

#1=150 psi,   #2=150 psi,   #3=150 psi,   #4=149 psi

(Standard Compression Ratio is 130 psi for 8.0:1 CR)

 

Cylinder Head Porting and Horsepower:

  There are many opinions on which cylinder head is better for porting but in reality any

cylinder head can be ported to work with the supercharger, it all depends what you want in

performance. I wanted a cylinder head that complimented the Supercharger and my driving

habits by having low to mid-range torque and power, this is where we spend most of our

time driving. I ended up doing my own "Do It Yourself" Port and Polished cylinder head.

 

  A port and polished cylinder head with 3 angle valves and seats will usually gain about

10-15 horsepower. An additional benefit of porting is is clearly reduces detonation, which

allows you to run either more ignition advance, boost, or both. You also should notice a

small reduction in boost, and this is normal. Why? You are essentially making the same

horsepower with lower boost because the cylinder head is flowing better, this creates

added performance and also allows you to install the High Boost Pulley.

 

Payen Head Gasket .043" Compressed:

 I used the Payen Head Gasket set CK665 and measured it brand new. The steel bore

rings measured 1.2mm or .04724", the black resin area measured 1.1mm or .043307". The

only area that compresses is the bore rings from .04724" down to .043" matching the black

resin area of the gasket. I reused this gasket 3 times and each time measured .043". That

is also another great point about this gasket, you can reuse it over and over. It is one of

the most reliable head gasket for the MGB.

Payen Head Gaskets comes in different sets: CK663, CK664, CK665.

All these sets use the same AK660 head gasket.

 

Changes made:

• Installed Payen Head gasket: With the added pressure of the supercharger having the best head gasket is a must. Very reliable and can be reused.

 

Squish or Quench Area:

  With a supercharged engine you may find having tight squish or quench characteristics

can work against you by helping speed up the flame travel when what you are needing is

to slow it down. The supercharger provides a lot of mixture turbulence, it homogenizes the

mix prior to induction, even when cruising along not providing much pressure, this effect

offsets the need for tight squish as needed with a "normally aspirated" engine. Once you

get rid of all squish or quench characteristics is when you can enjoy being able to add more

boost safely.

 

 I have a squish area of .075" (Head Gasket + Deck Height) and with 16.2cc dished

pistons this pretty much eliminated my squish or quench characteristics. I use a high boost

pulley with 7 psi of boost, 32° timing advance, 8.157:1 compression ratio, do not need any

boost controller devices or intercoolers, and still able to use 87 octane fuel with no hint of

detonation. Very dependable and reliable.

 

Changes made:

• I made sure my Squish area stayed at or above .075": This has proven to help provide more boost, more timing, slightly higher compression ratio, and 87 octane fuel. This all means more torque and horsepower...

 

Valve Clearances:

  Normal book valve clearance is .015" cold, intake and exhaust, for the early 18G series

cylinder head with 1.56" intake valves and 88G303 camshaft. If you think about this for a

moment, metal expands when hot causing valve clearances to close approximately .002"

from the .015" cold setting. This corresponds with the .013" hot setting that is also

mentioned in books. Either way of setting valve clearances ".013" Hot or .015" Cold" give

approximately the same clearances.

 

***Mr. Peter Burguess informed me of an engine tweak he uses. Since I no longer have a

standard engine, standard settings do not necessary apply. Set the inlet tappets .012" Hot,

with exhaust tappets at .015" Hot, and the spark plug gap to .035". This gives an even

distribution of BHP throughout the rev range. Also, because camshaft are not perfectly

phased follow the tappet clearance as you rotate the engine and set the clearance to the

loosest position as this help achieve the BHP in your engine.

 

  Valve clearance makes a small difference to valve timing and overlap. They affect the

opening and closing speeds of the valves. If the lash is to loose, you will not get the full

benefit of the opening and closing ramp profile of the cam lobe. This means the valve will

tend to slam open and shut more than if the valve lash were tighter. It can cause poor

closing conditions where the valve bounces off the seat which can happen at any rpm, but

usually happens at higher rpm's. If the valve lash is to tight it will hold the exhaust valve

off the seat causing the valves to get hot and increase the chances of detonation.

 

Changes made:

• Set intake clearances at .012" Hot and the exhaust clearances at .015" Hot: Provides an even distribution of horsepower throughout the rev range.

• Adjusted each valve by following the tappet clearance for the loosest position and than set the appropriate valve clearances: A very fined tuned engine that helps with the distribution of horsepower throughout the rev range.

 

Adjusting Valve Clearances:

  You can adjust your valves by adjusting 2 valves at one time by cranking the engine to

move the valves. Simply leave the spark plugs in, or take them out, and take the plug wire

off the coil. Disconnect the White & Brown wire from the ignition relay and by attaching a

wire to it, slightly touch the bottom live fuse in the fuse box or any power source that is

live. The slight engine crank will move the valves each time and adjust your valves.

Adjust Valves #1 and #3 when #8 and #6 are Fully Open!

Adjust Valves #5 and #2 when #4 and #7 are Fully Open!

Adjust Valves #8 and #6 when #1 and #3 are Fully Open!

Adjust Valves #7 and #4 when #2 and #5 are Fully Open!

Fully Open means Valve is in the down position or depressed. Then you Adjust Valves!

#1 Exhaust, #2 Intake, #3 Intake, #4 Exhaust, #5 Exhaust, #6 Intake, #7 Intake, #8 Exhaust

You can also adjust individual valves using the "Rule of Nine"!

Rule of 9!

Add the Valve Numbers and they will Equal 9.

Adjust Valve #1 when Valve #8 is Fully Open!

Adjust Valve #3 when Valve #6 is Fully Open!

Adjust Valve #5 when Valve #4 is Fully Open!

Adjust Valve #2 when Valve #7 is Fully Open!

Adjust Valve #8 when Valve #1 is Fully Open!

Adjust Valve #6 when Valve #3 is Fully Open!

Adjust Valve #4 when Valve #5 is Fully Open!

Adjust Valve #7 when Valve #2 is Fully Open!

 

Fine Tuning Valve Lash:

  You can use both methods listed above to find the valves and adjust. Again, because

camshafts are not perfectly phased you can also fine tune the valve lash where you must

rotate the engine to find the point where each valve has the widest clearance and than

adjust it. Takes a little more time but will have a fined tuned engine once completed.

 

Supercharger Distributor Curve:

 Next was getting the right advance curve to have timing spot on with the supercharger.

Timing is everything and you can loose 3-5 and more horsepower if your timing is off a

couple of degrees. Any distributor can be rebuilt but its all about the advance curve. I

had an Original Lucas 45D 41427 (E) distributor that was rebuilt and with a custom curve.

Superchargers like a lot of initial advance up-front and a curve that ends at 2600 to 3000

rpm's. This custom Supercharger curve gives you that "Seat of your Pants" feeling.

Above is my Original Lucas Distributor 41427E 45D4 1384

  This distributor was used as an Exchange or Replacement for Lucas Distributors #40897,

41144, 41220, 41288, 41290, 41264 and 41399. Most of these are the 25D distributors for

high compression engines from 1962-1971.

Original Curve for the 45D 41427 E	Degrees	RPM
Dwell	51+/-5
Static	+10
Strobe	Idle Setting +14	600
Centrifugal	+4	600
	6	700
	9	900
	15	1600
	20	2200
Vacuum - Ported - 5 -13 -10 degrees Starts: 5 hg in  Max: 13 hg in  10° Distributor (20° Crank)

Below is my "Supercharger Custom Curve" Specification Sheet:

Custom "Supercharger" Curve	Degrees	RPM
Dwell	51+/-5
Static	+10
Strobe	Idle Setting +18	800
Centrifugal	5	600
	+8	800
	11	1000
	12.4	1200
	13.6	1400
	14.8	1600
	16	1800
	18.4	2200
	19.6	2400
	20.8	2600
	21.4	2800
	22	3000
Vacuum - Manifold - 5-13-10 degrees Starts: 5 hg in  Max: 13 hg in  10° Distributor (20° Crank) 22° Mechanical Advance  +10° Static Timing   = 32° Total Advance

Notice how this Custom Supercharger Curve is basically "All in By 2600 rpm" only going up 1.2° to 3000 rpm.

 

Changes made:

• Rebuilt 45D distributor with a Custom Curve: Works flawlessly and allows the best possible advance curve to get the most out of my supercharged engine.

 

Vacuum Advance:

  With a custom curve I also had to find out what is better with the supercharger, ported

or manifold vacuum advance. The supercharger instructions state to connect the vacuum

advance tube to the barb fitting on the carburetor (ported) that resulted in lackluster

engine performance. Some say supercharger pull more air through the intake creating

different vacuum levels that changes everything. So how does vacuum work with the

supercharger?

 

 On the M45 supercharger a bypass valve is installed between the supercharger and the

air throttle body, allowing the supercharger to become extremely efficient in terms of

economy and parasitic power loss. The bypass is operated by a vacuum actuator control

unit that is normally closed. When vacuum is high (idle-cruising) the actuator opens the

bypass valve, equalizing the vacuum pressure throughout the system. When boost is

required (accelerating) the vacuum is decreased and the bypass valve instantly closes,

causing pressure to increase into the cylinders. This equalized vacuum condition virtually

eliminates the normal parasitic power loss of a forced induction system. During normal

driving the engine is very seldom in full-power, wide-open throttle. With a supercharged

engine, this is the only time the blower is actually being used. The rest of the time, at

part-throttle cruise, idle, or deceleration, even a supercharged engine has vacuum in the

intake manifold.

 

  A type of boost retard can be accomplished with a supercharged engine by hooking the

vacuum line from the distributor vacuum "advance" to the spare port next to the bypass

port. This will assure no vacuum advance is occurring while under boost. Manifold vacuum

actually drops slightly as the throttle position changes and thus the vacuum "advance"

actually retards timing slightly for better performance with a supercharger.

 

  When it comes to MGB vacuum units they are all vacuum "advance" units, ported or

manifold, the more vacuum applied the more advance applied and vice-versa, the only

differences being the start, max, and total degrees. I had several distributors that had

different ported and manifold vacuum advance characteristics and decided to try them all,

changing back and forth from ported to manifold vacuum in hopes of finding that perfect

match for my custom curve and engine modifications.

 

  What I found was the 5-13-10 vacuum advance unit (ported) connected to manifold

vacuum, perfectly matched my custom curve and engine modifications resulting in peak

engine performance, a smooth steady idle, improved throttle response, idle cooling and

efficiency, increased drivability, and improved fuel economy. It really changed how my

engine responds and feels.

 

My vacuum at idle is steady at 20 in/hg at 800 rpm's! Means engine is in Good condition!

Just to be sure, open and close throttle quickly: Jumps from 2 to 25 in/hg.

My vacuum jumps from 2 to 25 in/hg! Means engine in Good condition!

 

Changes made:

• Changed to manifold vacuum: Providing peak engine performance, smooth rock steady idle, improved throttle response, idle cooling and efficiency, increased drivability, and improved fuel economy.

 

Comparison Ignition Results:

  Classic Motorsports Magazine listed results of different ignition systems used in an MGB.

The below graph are dyno results using the same MGB as a test vehicle. The Blue lines at

the bottom indicate a stock 25D distributor with Points. The Green lines shows a power

increase when a Pertronix Ignitor is added, it is also smoother, indicating better drivability.

The Red lines shows the effects of adding a MSD 6A along with the Pertronix Ignitor which

provided an additional power increase with even better drivability. The Electronic Pertronix

Ignitor easily outperformed the points distributor gaining an extra 3.5 horsepower at the

wheels. The Pertronix Ignitor along with a MSD 6A Ignition Control increased another 2.4

horsepower at the wheels. That is an extra 5.9 horsepower and 2 ft-lbs of torque at the

wheels over the baseline with points distributor.

 

  The main point of interest with a Pertronix Ignitor and MSD Ignition Control is that you

not only have easier starting and a reduction of choke needed during warm up but if you

look at the graph (Red Line) you can easily see a very noticeable difference in drivability

because an engine equipped with this setup runs so much more smoothly.

 

Blue Line = Points     Green Line = Ignitor     Red Line = Ignitor & MSD 6A

 

My Supercharged MGB Ignition Set Up!

 

MSD 6A Ignition Control:

  The MSD 6A is a great performance upgrade that can be added to MGB's. Benefits such as

easy starting, steady smooth idle, reduced plug fouling, quicker throttle response, and

increased fuel economy can be expected. It produces a sequence of powerful multiple

sparks for every firing of the spark plug ensuring complete combustion of the fuel mixture

resulting in improved performance and power.

 

 MSD 6A features a capacitive discharge ignition design, The majority of stock ignition

systems are inductive ignitions, the coil must store and step up the voltage to maximum

strength in between each firing. At higher rpm's, since there is less time to charge the coil

to full capacity, the voltage falls short of reaching maximum energy which results in a loss

of power or top end miss.

 

 The MSD 6A ignition features a capacitor which quickly charges within 1 millisecond with

460-480 volts and stores it until the ignition is triggered. With the captive discharge

design, the voltage sent to the coil is always at full power even at high rpm.

 

  The MSD-6A produces full power multiple sparks (3 sparks) for each firing of a plug. The

number of multiple sparks that occur decreases as rpm increases, however the spark series

always last for 20° of crankshaft rotation. Above 3000 rpm there is simply not enough time

to fire the spark more than once, so there is only one powerful spark.

 

  The MSD 6A unit installs between the distributor and the coil. The input to the MSD is

isolated electronically from the distributor output, whether that be points or electronic, so

there is virtually no load on the distributor, regardless of the output voltage of the coil and

depending on the coil you use.

 

 MSD tech support recommends using a coil that has 1.5 ohms of primary resistance "or

less" with the MSD 6 series ignitions. The MSD 6A is recommended with the MSD Blaster

II coil, 0.7 ohm, oil filled, 45,000 volts.

 

Changes made:

• Installed a MSD 6A Ignition Control: Easy starting, steady smooth idle, reduced plug fouling, quicker throttle response, fuel economy, improved performance and power.

 

Complete Ignition Setup:

  MGB's run better slightly rich, the same with a supercharger installed which can lead to

slightly un-burnt gas being sucked out the exhaust pipe. The MSD 6A ignition controller

eliminates this problem by providing a complete combustion burn. Next I needed to match

up components that would all work perfectly together.

  For the coil I used the super low resistance 0.6 ohm Pertronix Flamethrower II, 45,000

volt, Epoxy filled coil, mounted upright, with a .035 spark plug gap. This coil enables larger

spark plug gaps for greater fuel efficiency and more power.

  Next was the distributor. I have a 45D4 41427E distributor that had red heel contacts. I

replaced the points with the Ignitor LU-143 electronic ignition which is the recommended

unit for 4 cylinder Lucas 43D/45D distributors (1974-1980) that has red fixed points. The

LU-143 Ignitor is recommended for use with 3.0 ohm coils.

 

  You may ask why I use a 0.6 ohm primary resistance Flamethrower II coil. It works like

this, the LU-143 Ignitor triggers the MSD 6A Ignition Control which then triggers the coil.

For this reason it is the MSD 6A that needs the correct coil, not the Ignitor. This also

means very little current flows through the distributor.

 

  The MSD 6A Ignition Control, Flamethrower II 0.6 ohm coil, with a Pertronix Ignitor

LU143 makes a very matched up ignition system. The engine idles smoothly at 600 rpm,

but I prefer to keep the idle set at 800 rpm with the supercharger.

 

Changes made:

• Completely matched ignition system: All the benefits mentioned above for the MSD 6A and ensures a complete combustion burn that eliminates any un-burnt fuel.

• Keeping the idle at 800 rpm prevents any run-on or dieseling.

 

Spark Plugs:

  The standard spark plugs with the supercharger are NGK-BPR7ES. These colder plugs

caused fouling of the plugs and a slight hesitation. I installed one step hotter, NGK-

BPR6ES which are standard plugs or equivalent to Champion RN9YC used in MGB's. This

eliminated the hesitation and the plug from fouling, providing a normal light tan plug

appearance on the insulator nose. Spark Plug gap is set at .035

 

Changes made:

• Changed plugs to NGK-BP6ES: Provides the correct plug appearance and corrected hesitation problem.

 

180 Degree Thermostat:

  A thermostat has one simple function and that is to stop engine coolant from flowing

below a certain temperature, and to allow it to flow at or above a certain temperature. We

have to change our thought from a normally aspirated MGB to a supercharged MGB. Boost

pressures creates heat, lots of it. Do everything you can to eliminate heat and reduce the

chances of detonation. You should have an engine temperature consistent around 180°.

For most supercharged installations a 180° thermostat is recommended. I also added a

blanking sleeve with the 180° thermostat. It works well to shut off the bypass port and

help restore coolant flow when your engine is at operation temperature.

Blanking Sleeve!

 Cooler engine temperatures also help decrease the spontaneous combustion of the

unburned air-fuel mixture in the combustion chamber other wise known as knocking,

pinging, or detonation. By keeping the pistons, cylinder head and walls, cooler, helps to

reduce or eliminate hot spots, which could prematurely ignite the fuel causing pinging and

detonation. A minimum water temperature of 180° is required for the cylinders to allow

fully homogenized air/fuel mixture to combust efficiently.

 

  If you want optimum engine temperature for increased engine longevity, supercharger

efficiency, and performance, use a 180° thermostat. Heat isn't power. Air x Fuel x Ignition

= Power. The colder the air the more dense the oxygen molecules, the more power per

cubic foot. With a cool intake charge, and a cool cylinder head, you can bring in a lot more

timing lead and more thoroughly burn the fuel mixture and convert that into energy pushing

the piston down vs. spewing it out the radiator or exhaust. Cool cylinder heads and a cool

air charge is the key to making even more power with the supercharger.

 

  My cooling system works the way it should. Long as I am driving at speed, anything over

20 mph, even in the high humidity, hot tropical climate we have here in American Samoa,

my electric cooling fan never comes on. The operating temperature stays steady at 182°,

only when I come to a stop and idle will the temperature start to rise and the electric fan

comes on. Soon as I start driving at speed the electric cooling fan shuts off and the

temperature stabilizes at 182°.

 

Changes made:

• Installed 180° thermostat and blanking sleeve: Keeps engine temperatures consistent around 182°, reducing the chances of detonation, also helps in providing more power.

 

Radiator Fan Switch:

  I use a heavy duty Intermotor Fan Switch that I custom made to fit into the radiator. This

switch has a temperature rating of 190.4°F to 181.4°F that turns on and off my 14" electric

cooling fan. The off rating of 181.4°F exactly matched my engine operating temperature of

182°F when driving at speed and no cooling fan is needed. This setup keeps my engine

temperature within 9° at all times.

 

Changes made:

• Installed Intermotor radiator fan switch. Keeps engine temperatures consistent at 182°, keeps engine temperature within 9°, reduces the chances of detonation, also helps in providing more power.

 

Electronic Heater Control Valve:

 Since I removed the heater controls to make room for a boost gauge and volt meter I

needed a way of turning on the heater control valve. I found an Electronic Servo Heater

Control Kit 50507-VUA Kit that comes complete with a under dash rotary control, servo

heater ECU assembly, and the valve assembly from Vintage Air. It takes a 5/8" heater

hose.

Electronic Servo Heater Control Valve!

  When you remove the old heater valve Pembroke makes a nice replacement billet

aluminum heater flange with two socket head screws in either natural aluminum or black

anodized. All you have to do is attach two pipe fittings. Mine matches up to the 5/8"

heater hose which is the same size as the heater valve connections. Simple set up and

works great. The dial to turn on and off the heater servo is located on my dash. See picture

below of my dash board.

Pembroke Billet Aluminum Heater Flange!

 

Exhaust System:

  A good exhaust system will make a huge difference to the breathing of your engine and

especially with a supercharger that is pushing more air in and out of the engine. I used a

Peco Header that was Jet Hot coated and matched up with a Peco Big Bore (2") free flow

exhaust system that can boost mid-range power by up to 5 horsepower at the wheels.

Peco Header and Exhaust System!

 

Peco Header:

  The MGB is unique having three exhaust ports, with the Peco header each side port has

it's own tube and the center port being shared by two cylinders uses a Long Center Branch

(LCB) tube which is larger than the two side tubes. Engines producing more torque and red-

line at 5,500 rpm's need a longer tube length of 36". Longer tubes pull the torque down to

a lower rpm range. Shorter tubes moves the power band up into a higher rpm range. This is

what is meant by the term "Tuned Length". The tube length is "Tuned" to make the engine

operate at a desired rpm range.

 

Changes made:

• Installed a Peco Header and Exhaust System: provides better breathing of the engine, pulls torque to lower rpm range, and boost mid-range power.

 

Peco Header with Jet Hot Extreme Sterling:

  Jet Hot Extreme Sterling is very similar in appearance to Sterling, not as bright. It will

hold its shine 200°F higher and can actually withstand temperatures up to 1700°F. This

amazing finish normally cuts down about 400°F on the skin temperatures of pipes. This

coating is great for supercharged applications. Extreme Sterling will normally boost power

when applied to headers for two reasons. First, the coating promotes denser, more potent

fuel/air charges by insulating the engine bay from exhaust heat. At the same time, it

accelerates the pulsed-vacuum effect on "Tuned" headers, resulting in more scavenging of

cylinders. The increased velocity of exhaust gases produced by higher exit inertia not only

clears each cylinder more quickly it also draws in the next fuel/air charge more efficiently.

 

  The optimum situation occurs with our four cylinder engine because of its firing cycle. For

every 180° of crankshaft rotation there is one exhaust pulse entering the collector. This is

ideal timing because, as on pulse exits the collector, the next exhaust valve is opening and

the vacuum created in the system pulls the exhaust from the cylinder. In this ideal 180°

cycling the collector outlet diameter needs to be 20% larger than the primary tube

diameter. A good example is the Peco header with 1¾" primary tubes going into a 2"

collector outlet diameter. The rule of thumb is two tube sizes. This keeps the velocity fast

to increase scavenging, especially at low rpm's.

My Jet Hot Extreme Silver Peco Header!

 

Changes made:

• Peco Header with Jet Hot Extreme Sterling: Reduces engine bay temperatures to allow a more potent air/fuel mixture and accelerates pulsed vacuum effect on the Peco Header, promoting more power.

 

Supercharger Heat Shield:

  Heat robs horsepower, this means reducing operating temperature of the supercharger

unit is very important. This heat shield has a high tech aluminized radiant barrier material

to lower temperature, increases supercharger efficiency, and also isolates the air filter from

the hot exhaust temperatures providing cooler air around the air filter. The reduced heat

around the carburetor allows you to adjust the fuel mixture screw without burning your

fingers. It has a 12° drop at 60-70 mph driving temperature, and a 30° drop in temperature

after slowing down from freeway speeds using a stock header.

Supercharger Heat Shield!

 

Changes made:

• Installed Supercharger Heat Shield: Reduces operating temperature and increases supercharger efficiency, isolates hot exhaust from air filter, providing more power.

 

Custom "Air Filter Assembly:

  The air filter supplied with the supercharger is slightly small causing restricted air flow

and a rich mixture above 4000 rpm's. Most installations end up changing the BCA needle to

a BBC needle, which is the next leaner needle but still needs to be sanded down in stages.

Instead of changing and working with needles I felt by having a larger air filter this would

lean out the mixture and provide more air flow at the same time. Using a LM-1 air/fuel

meter and a G-tech meter I tested the OEM, K&N RU-410 and K&N E-2400 air filters. It was

a simple answer, the bigger K&N E-2400 air filter provided the best results throughout the

rev range.

 

  When I installed the supercharger I did not need the spacer between the carburetor and

the air filter. Removing the spacer achieves 5 extra horsepower. Early year supercharger

kits do not have a spacer, later years because of the brake booster and master cylinder.

 

  With the extra area I was able to fit a SU Filter Base used on the 1962-74 MGB air filter

system that has this velocity stack as part of its design. Velocity stacks reduce turbulence,

improves metering accuracy, increases airflow by reducing restriction, while straightening

and speeding air flow. I had to modify the filter base to fit the supercharger and with some

drilling and grinding made my own velocity stack. Next I used a 90° 4" PVC pipe that has

a 3.5" inside diameter and fits perfectly to the 3.5" outer diameter of the velocity stack. A

little more ingenuity and I fitted the air filter. The complete air filter assembly can be

taken off, cleaned, oiled, and installed by loosening a one screw ring clamp.

 

  The finished air filter assembly looks like it was made for the supercharger and fits up to

a velocity stack for mounting. It is the perfect height to close the hood (bonnet) without

hitting the air filter. The upward 90° angle lifts the air filter further away from the exhaust

pipes. The larger size filter no longer has restricted air flow, it leaned out the mixture with

the air/fuel ratio I was looking for without changing needles, and also picked up a little

torque and horsepower.

My Custom made K&N E-2400 Air Filter Assembly!

 

Changes made:

• Custom Air Filter Assembly: Larger E-2400 air filter, moved further from exhaust pipes, leaner mixture, denser air, no need to change needles, provides more torque and horsepower throughout the rev range.

• Installed Velocity Stack: Velocity stacks reduce turbulence, improves metering accuracy, increases airflow by reducing restriction, while straightening and speeding air flow.

 

Reducing Engine Bay Temperatures or a Cold Air Intake:

  In theory denser air provides more horsepower. For every 5.4°F or 3°C decrease in

temperature of air ingested by the engine is lowered, power output is raised by 1 percent.

The problem with the Supercharger is the carburetor and air filter is directly over the

exhaust manifold and ingest all this exhaust radiated heat. Moss R&D actually tried a cold

air feed tube on the supercharger test vehicle and found not much difference in actual

intake air temperature at speed. The next step for them was to make a heat shield for the

exhaust manifold and this made a tremendous difference to intake temperature at idle and

speed. If the heat shield alone made such an improvement over a cold air feed why not

take it one more step by reducing engine bay temperatures even further. This is exactly

what I did to provide denser air to the engine.

 

1. My engine and cooling system works the way it should. I use a 180°F thermostat with blanking sleeve, gives me a steady 182° normal operating temperature. This means the thermostat is barely open and maintaining engine operating temperatures. Also installed a 181.4°-191.4°F fan switch that keeps engine temperatures within 9°.

2. The exhaust manifold gives off a lot of radiant heat that increases engine bay temperatures more than anything else. With the header Jet Hot coated this greatly reduces engine bay temperatures. The supercharger stays cooler and most importantly is the reduction of exhaust radiant heat around the carburetor and air filter. Compared to a stock manifold the Jet Hot header outside temperature was reduced by 50%, translating into a reduction of engine bay temperatures and a much denser intake charger. (Stock Manifold 390°F compared to Jet Hot Peco Header 192°F)

3. To reduce the operating temperature of the supercharger a heat shield was installed. This keeps the supercharger cooler and reduces heat. The design of the heat shield also isolates the carburetor and air filter from exhaust radiant heat and helps provide denser air around the air filter.

  

  With the 3 changes made above I found with the reduction of engine bay temperatures

there was no need for a cold air intake. The biggest advantage is the air being inhaled into

the engine is denser, more fuel can be mixed with it resulting in a more powerful fuel/air

charge, it also aids in reducing the chances of detonation.

 

Changes made:

• Reduced engine bay temperature: Reducing engine bay temperature by over 200° translates into denser air, providing more power output.

 

Reduction in Vehicle Weight!

  After all the changes made to my MGB by getting rid of old parts and adding new lighter

weight parts, removing side markers, seams/beads, sandblasting, etc.., I ended up with a

total weight loss of 196 lbs. Original curbside weight was 2416 lbs and had it weighed at

our local scrap yard scales, 2220 lbs with a full tank of gas, spare tire, jack and tool bag.

 

Changes made:

• Reduced vehicle weight: A lighter vehicle will run faster, accelerate quicker, and consumes less fuel. 

 

High Boost Pulley:

  With the changes made to the engine I was able to install the 2.6" High Boost Pulley. If

you want more torque and horsepower you can change from the original 2.75" pulley and

install the High Boost Pulley that will increase boost from the standard 5-6 psi to 7-8 psi.

This pulley is recommended for use on engines that have a 8.0:1 compression ratio or

cylinder heads that have been flowed. Each pound of boost is worth approximately 4~5 hp.

If you do install this pulley you should have a 2 psi increase. If you have a slight increase,

no increase, or a drop in horsepower than most likely you have reached your limits, maybe

a flow restriction, or some other problems.

 

  The problem with pushing more than 8 psi on the M45 (with the 2.6" pulley) is that the

air charge will heat up dramatically after this level. This is due primarily to the simple law

of thermodynamics which states that any air/gas will heat up as it is compressed. In

addition, you will also get added heat from the operation of the supercharger (friction).

 

Changes made:

• Installed High Boost Pulley: Provides more torque and horsepower.

 

87 Octane Fuel:

 The lower the octane the best power potential you will have because it burns better and

yields higher BTU per lb of fuel. My supercharged MGB with a high boost pulley and 7 psi of

boost easily runs on 87 octane fuel. Higher octane fuel is only used because of its ability

the resist detonation. Another added benefit is the savings with fuel economy. If you can

get your engine tuned properly you should have no problem using 87 octane fuel unless you

have a high compression engine with the supercharger.

 

Other Improvements added:

 

Lowered Front and Rear Suspension:

  My MGB has OEM 5/8" front sway bar and 11/16" rear sway bar and was left unchanged.

On the rear suspension I installed 1" lowering blocks, rear suspension polyurethane kit

(Red), shorter rebound straps and telescopic shocks. On the front suspension I first tried

installing the Moss Red 480 lb/in (8 ¾" free length) lowering coils but for some reason it

lowered the front suspension way to much. The OEM coils were rated at 372 lb/in (10" free

length) and I needed something that was shorter. I read that the BHH-1077 coil springs

used on the MGB GT and MGB GT V8 were rated at 480 lb/in (9.1 free length) and installed

them along with front suspension polyurethane kit, shortened bump stops and new

crossmember polyurethane pads. This was exactly what I wanted with a 1" lowered front

suspension matching the 1" lowered rear suspension. There was a noticeable difference in

improved handling, steering and appearance. The front spoiler and exhaust both have a 5"

ground clearance.

 

Mini-Lite 8 Spoke Rims:

 When it came time for rims I wanted a cleaner look and installed Mini-Lite Style Alloy 15"

8 spoke rims made in the UK. I used conical 1½" long Cold Forged Steel lug nuts that stick

out more than the shorter OEM lug nuts. Tires are 195/65R15.

Mini-Lite 8 Spoke Rim!

 

Space Saver Tire:

 I did not want the big OEM spare tire and used the pre-1986 Saab 900 Space Saver Rim

that has the same 4 x 4.5" PCD. The tire that was on it T115/70R15 was old and short. I

wanted it a little bit wider and taller and installed a brand new T125/70D15. This one

size up makes a big difference when you have 15" rims with 195/65R15 tires.

 

Saab 900 Rim with T125/70D15 spare tire!

 

Custom MGB Safety Seat Belts:

 I wanted a very reliable set of seat belts more like the MG RV8 and found a company in

the that sells inertia seat belts that are specifically designed for the MGB. They come with

mounting brackets, fixings and instructions.

 

  Unlike most seat belts these come with pivoting belt guide that prevents the belt from

twisting as the retract. The inertia reel locking mechanism is engaged by just that, inertia.

You can park the car at any angle and still put the belt on with ease. They do not lock up

when on an incline because the reel was designed to be fitted vertically at the bottom of

the door pillar. They only lock up when they feel enough inertia to lock them up. They even

come with black screw caps to dress it up.

 

EZ Electric Power Steering:

 With my MGB having many modern accessories I wanted to take it one step further by

adding power steering. Many modern cars now use electric power steering and there is a

company in Holland that makes an Electric Power Steering conversion for the MGB.

 

  I ordered the conversion and to be truthfully honest I had to make some modifications for

it to work on the US market RB MGB. The company was very helpful in trying to fabricate

new parts to make it fit better but the new parts did not work either. My US RB MGB must

have been the first to use this conversion. All it takes is a little ingenuity and you can

make it fit and work perfectly. It seems this conversion was set up for the early steering

columns and not the later US RB collapsible columns.

 

 The complete electric power steering assembly fits underneath the dash and is completely

hidden. You would never know it was there unless you look under the dash. It is truly

speed sensitive and will steer light at low speeds and not become lighter at high speeds.

The amount of assistance can be selected by turning a potentiometer, the driver can select

the desired feel they want. In the unlikely event that the electric does not work, fuse

blown or any defect, the MGB would steer just like it did before the conversion. The EZ

electric power steering works without making a sound, it cannot leak and is completely

maintenance free. A very well manufactured electric power steering conversion for the MGB.

 

  With my MGB having larger tires and a smaller steering wheel I set the potentiometer at

the lowest possible setting. One finger will easily turn the steering wheel in a parking lot.

If you see a pot hole or anything on the road you can easily steer around it with instant

response. You may loose some of that MGB feeling at lower speeds but for me it was worth

the conversion. Once you gain in speed you start returning to that same MGB experience

you always had. It does make the MGB feel like a modern car at lower speeds but for me it

was well worth it in every way.

 

EZ Electric Power Steering! All hidden under the Dash!

 

Carter "P60504" Fuel Pump:

  When it came to fuel supply I used a Carter P60504 In-Line 12v Electric fuel pump. It is

a Gerotor, 30 GPH free flow rate, self-priming, negative ground, positive displacement fuel

pump that I mounted in the same location as the OEM pump. Its small, has a filter before

the pump, very quiet, no ticking noise, rated 2.5~4 psi maximum, and will keep the entire

fuel line to the carburetor pressurized to alleviate any potential vapor lock problems. It

works extremely well with the supercharger and HIF44 carburetor. I have used this pump

for over 20 years and never had any problems. (As long as the output pressure on any kind of pump

does not exceed 4 psi there is no need for a regulator with a SU or Weber carburetor)  

Carter P60504 Fuel Pump Kit!

 

96 amp GM/Delco CS-130 Alternator:

  I replace the old alternator with a newer GM/Delco Alternator. More than enough power

output to handle any electrical add-ons to your MGB. Simple bolt on with no modification

needed. Easy two wire hook up. I ordered mine with a 4 rib pulley.

96 amp GM/Delco CS-130 Alternator!

 

 Cibié H4 7" E-Code Headlamps with City Lights:

   I wanted headlamps that would shine up the road and after reading Daniel Stern Lighting

website. I e-mailed Daniel and asked him what would be the best headlamps for an MGB.

His response was the Cibié H4 7" E-Code Headlamps with City Light. I informed him that I

already had the Heavy Duty Wiring Harness with Relays and he suggested to install 100/90

watt Narva Bulbs. The "City Light" is nothing more than a small white 5 watt bulb that

illuminates the whole headlamp in a "Pilot Light" sort of way. This makes for a large-area

parking lamps, and if a headlight bulb ever burns out oncoming traffic still sees you as a

double-track vehicle. Very good idea and legal in the United States. After I installed the

Cibié Headlamps and made sure the headlamps were correctly aimed it was time for a

drive. Wow, that is all I can say. These light are fantastic.

 

High Torque Gear Reduction Starter:

  I replaced the old starter with a new 1.2 horsepower High Torque Gear Reduction starter

motor for all 1968-1980 MGB's. The mounting plate can turn 180°. Very easy to install and

very depending. Starts your MGB on the 1st crank.

High Torque Gear Reduction Starter!

 

AAW PowerBlock:

  I wanted a nice clean appearance instead of the blue wire harness, fuse block and extra

relays that are added to improve the electrical system. With the many modern options now

added to my MGB I wanted the best and most modern electrical system that I could install.

I decided on the Advance Auto Wire (AAW) that has 7 relays and 8 fuses in one location,

the PowerBlock. I also made a new wiring diagram specifically for my MGB that includes

every electrical component. It was a long tedious job because I wanted the wires hidden.

The results speaks for itself!

No more under the Hood Wires and Relays! Very Clean Looking Appearance! 

 

My MGB Dashboard and Radio Console:

  All my OEM gauges were replace with 8 modern Vision Black Gauges by VDO. These

gauges light up white, bright and all gauges are very readable at night. Speedometer and

Tachometer have two lights inside.

 Here is a list of VDO gauges and other accessories I installed on my MGB:

• Speedometer: 4" 120 mph Programmable Speedometer-Electric Vision Black: The best feature with this gauge is you can install any size tire and reprogram the speedometer for the correct mph. It also needs a speed sensor (Hall Effect Sensor) attached to the speedometer cable

• Tachometer: 4" 8000 rpm Tachometer-Electric Vision Black: This tachometer will work with the MSD 6A Ignition Control and Does not need the MSD tachometer adapter.

• Fuel: 2 1/16" for 240-33 Ohm Sender Fuel Level Vision Black: The fuel gauge will match the sending unit on the gas tank. 240 ohm means Empty, 33 ohm Full.

• Oil: 2 1/16" Oil Pressure Gauge 100 psi Vision Black: This oil gauge needs a 10-180 ohm sender. Sender Oil: 100 psi 1/8-27NPT 10-180 Ohm

• Water: 2 1/16" 250°F Engine Temperature Electric Vision Black: This water temperature need a 10-180 Sender. Fits into block. Sender Water: Temperature Sender 250/120C 5/8-18 NF-3- 209F+/-5. 180 ohm reading temperature is 250°F.

• Outside Air Temperature: 2 1/16" Outside Temperature Vision Black

• OEM Dash Lights: OEM High Beam, Ignition, Hazard, and Brake warning lights.

• Cooling Fan Switch: Safety cooling fan switch that can over-ride the thermostatic fan switch. Installed as a safety feature if I ever need it.

• Electronic Heater Control Switch: This switch controls my electronic servo heater control valve. No cables at all, just turn the knob, adjusts to any opening for flow.

• Security Alarm: When armed the switch on the dash flashes red. It is a led light that consumes hardly any power. You can leave it on for 3 months and it still will not drain the battery. Very bright and everyone can see it flashing.

• Radio Console: Kenwood Receiver.

• Boost: 2 1/16" Turbocharger Gauge Vision Black (Vacuum & Boost)

• Voltmeter: 2 1/16" 16 volts Voltmeter 12 volts Vision Black

• Lighter: OEM stock lighter

• Red Light: The red light switches on when the cooling fan is working.

• Black Light: Seat Belt light.

 

 

Custom Made Fiero Seats:

  I wanted sportier seats that were more comfortable and installed Fiero seats with

custom made Two-Tone Black & Tan Leather seat covers with black welts. A black leather

strap was installed on the pull handles to lift the seats forward, and also on the top of the

seat for the seat belts to pass through. Installation was pretty straight forward. I did have

to change the drivers seat with the passenger seat. With the seats exchanged the seat lift

handle faces towards the middle tunnel. When it comes to comfortable seats these are the

ones. The Fiero seats have a harder cushion compared to most seats. These seats are 2"

lower than OEM seats and gives you plenty of room to get in and out of your MGB. They are

also slimmer in depth which provides longer leg room. These seats give you that feeling of

being in a real sports car. I also removed the interior door rails and installed the same

black leather as the seats to bring together the interior.

My MGB Fiero Seats are featured on Mr. Mikes web-site:

www.mrmikes.com/mgraysamoa.htm

Fiero Seats with Custom made Seat Covers!

 

Mohair RV8 Convertible Top:

 Many people wish the MGB convertible top would fold down easier. That is when I started

looking into the MG RV8 convertible top. Owners have stated that this style top folds down

easy and is just as easy to pull up if it rains. This is due to the fact that the complete top

has hood/top finishers that is permanently screwed into the cars frame.

 

  I was lucky in that the same company that manufactured the RV8 Top at the time also

custom made the RV8 top to fit the MGB top frame. It is made of Mohair and has a zip

down window. The plate lift dots are concealed under the mohair fabric to give it a clean

look. The zip down rear window is wider at the bottom and more stylish.

 

  When I installed the top it fit like a glove. My first try at putting the top down really

surprised me as it just fell right down into place. When I reached behind me I pulled

the middle and the top frame just came right up. All you need is a couple seconds either

way. I keep my top permanently mounted all the time with not need for a top frame cover.

This allowed me to install a 3rd brake light.

 

Custom 3rd Brake Light:

  I always wanted to install a 3rd brake light on my MGB but nothing seemed to look good.

With the Mohair convertible top I never use the top cover because it looks good folded

down. This gave me the idea of installing the 3rd Brake Light to the convertible top. With

some mohair material and a 3rd brake light I finally came up with a design that would look

right and part of the convertible top. See what you think:

Custom made 3rd Brake Light Sewn into Mohair Convertible Top!

 

Why I performed my own "Do It Yourself" Supercharger Cylinder Head:

  I installed 2 different cylinder heads; a stock Cam-1106 cylinder head with 1.56" intake

valves and a Professional Port & Polished 12H1326 cylinder head with 1.625" intake valves.

I used a G-Tech meter to measure torque and horsepower, along with 0-60 mph results to

compare these 2 cylinder heads:

 

***The stock CAM-1106 cylinder head provided more low and mid-range torque/power but

with a loss of high-end horsepower. Peak power at 4500 rpm and the torque curve was

not as broad and flat as I would have liked.

 

***The 12H1326 fully ported big valve cylinder head provided more high-end horsepower

with a very noticeable low-end and some mid-range torque and horsepower loss. Peak

power went up to 5119 rpm. Normal city driving seemed useless with no low-end torque. It

felt like I always had to be in the mid-range or higher to accelerate. High-end power means

nothing if you do not have a good power curve. The torque curve showed this weakness. I

felt this cylinder head had a loss of low and mid rpm because of less air speed in the larger

ports.

  

  These 2 results really made me think about what I wanted in a cylinder head with the

supercharger. My goal was to get the most out low to mid-range torque and horsepower.

 

**** When it comes to porting any large port can move a lot of air, but a "Smaller Port"

moving just as much air will create a flatter torque curve and be more effective with high

velocity and great throttle response. The right size ports are the ones that are not to big

and not to small. This statement really made me try my own port and polish cylinder head!

 

****Smaller valves are used for more low to mid-range torque. They create high air

velocity into the cylinder for good fuel mix at low speed. They also create a higher vacuum.

 

****High peak horsepower numbers, although very impressive, is not as important as the

"Area under the Power Curve" which ultimately determines drivability. People drive so

infrequently at the peak power range, that it is pretty much an insignificant number. Street

performance engines are all about drivability, throttle response, and low to mid-range

torque and power.

 

  I was now ready to perform a "Do it Yourself" porting with a 12H4736 cylinder head that I

felt was the best cylinder head because it had that little extra with an improved intake port

design and redesigned cooling passages that assisted in preventing over heating of the

rear cylinder. The larger coolant ports provided a greater service area to assist with higher

combustion temperatures and with the supercharger on boost this surely is an added plus

to the engine.

 

  I maintained the 1.56" intake valves as they would maintain low to mid range torque, and

added 3 angle valve cuts for better air flow and cooling of the valves. Changing the seat

angle from 45° to 30° produces improvement in low lift flow. With the supercharger

achieving more cylinder filling this also meant more exhaust gases needed to get out. The

exhaust valves are large enough and remained at 1.34", only adding 3 angle valve cuts and

to the seats. When it came to porting the exhaust ports the guide boss is the next area

needing the most work. It is intrusive and has an adverse effect on flow in the mid to

upper lift ranges. The guide boss is needed to conduct heat from the valve guide, which in

turn is needed to conduct heat from the valve stem. Instead of leaving or removing the

exhaust guide boss I decided to reduce its size by tapering the boss around the guide and

into the throat area making it into an aerodynamic shape. The throat and port areas were

cleaned up removing any imperfections, blended in, and produced a smooth surface and

finish. There was no need to make these ports any larger. Intake ports were cleaned up

and blended, removing imperfections, port divide sharpened at the split to aid swirl, and

keeping the ports on the rough side to decrease fuel condensation. Again, no need to make

the ports bigger. Cleaning up all the ports removes enough material the way it is. Finally,

the combustion chambers were flattened and smoothed. Chamber volume was checked and

double checked so they all measured exactly the same.

 

Results of my "Do it Yourself" 12H4736 Cylinder Head:

  When I looked at the G-Tech results it was like having both cylinder heads combined into

one. Compared to the CAM 1106 and 12H1326 I had no loss to low-end torque and power,

it increased. There was no loss to high-end torque and power, it increased. As stated

above and this holds true: "Any large port can move a lot of air, but the 'Smaller Port"

moving just as much air will create a flatter torque curve and be more effective with high

velocity and great throttle response". My "DIY" 12H4736 cylinder head has a broad, flat

torque curve. Low-end torque jumps right up to 120 ft-lbs of torque at 1500 rpm, reaches

its peak at 3546 rpm, and at 4750 rpm I still have 120 ft-lbs of torque. Low to mid-range

torque and power is exactly what I wanted and achieved, high-end horsepower was an

added bonus. I also had a drop in boost pressure, this meant that the head was flowing

better and allowed me to install the High Boost Pulley for more torque and horsepower. My

"Do It Yourself" cylinder head falls into the category of not to much or not to little,

matching perfectly with all engine modifications.

 

"The best tuned engines are the ones that have careful planning

 and the correct combination of subtle modifications!"

 

 

Performance Results for my Supercharged MGB!

  The below graph is my Torque and Horsepower curve that clearly shows the performance I achieved with my Supercharged MGB. I wanted to show the power band from 1000 to 5000 rpm, my maximum rpm range when driving on the street. You can clearly see after 5000 rpm's there is more high end horsepower but as stated people drive so infrequently at the peak power range that it is pretty much an insignificant number.

This is what they call a broad, flat Torque Curve!

Actual Street Performance Results:

114.3 RWHP @ 5089 rpm and 128.1 ft-lbs Torque @ 3546 rpm

SAE Net Horsepower and Torque --- Brake Horsepower (BHP) at the Flywheel:

145 SAE Horsepower @ 5089 rpm and 145 ft-lbs SAE Torque @ 3546 rpm   

  The G-Tech Pro measures the amount of torque and horsepower to accelerate your vehicle when driving on the road after all possible losses, including drivetrain loss, rolling resistance, and aerodynamic drag. Aerodynamic Drag accounts for most of the energy loss as speed increases, at 5000 rpm's I had a 7.2 horsepower loss. This is one reason why the G-Tech gives better results on the street because it deducts this loss along with all the others.

 The G-Tech will read lower than Rolling Road Dyno Results!

 

My Supercharged MGB 0-60 mph Results!

 

Average 0-60 mph in 7.28 seconds

 

Comparing a 2005 Mazda MX-5 (Miata) to my Supercharged MGB!

2005 Mazda MX-5 (Miata)	1977 Supercharged MGB
Engine: 1.8L 1798cc I4	Engine: 1.8L 1798cc I4 Supercharged
Compression Ratio: 10.0:1	Compression Ratio: 8.1:1
SAE Horsepower: 142 @ 7000 rpm	SAE Horsepower: 145 @ 5089 rpm
SAE Torque: 125 ft-lbs @ 5000 rpm	SAE Torque: 145 ft-lbs @ 3546 rpm
Rear Wheel HP: 109.9 @ 7000 rpm	Rear Wheel HP: 114.3 @ 5089 rpm
Torque: 103.5 ft-lbs @ 5000 rpm	Torque: 128.1 ft-lbs @ 3546 rpm
Curb Weight: 2447 lbs	Curb Weight: 2220 lbs
Fuel: 91-93 octane	Fuel: Regular 87 octane
0-60 mph: 7.8 seconds Actual Road Test	0-60 mph: 7.28 seconds Actual Road Test

2012 Mazda MX-5 / MZR 2.0L 16 Valve 4 Cyl / 2511 lbs

0-60 mph in 7.3 seconds

167 SAE HP @ 7000 rpm & 140 Ft-lbs SAE Torque @ 5000 rpm

 

Driving my Supercharged MGB:

  Driving my Modernized Supercharged MGB is breathtaking, thrilling and the excitement

never goes away. It has all the comforts of a modern sports car, is extremely dependable

and has excellent tractability for ease of driving. With Electric Power Steering this MGB

really feels modern, especially at low speeds, when parking or backing up. Lowering the

suspension and with wider tires makes it sticks like glue around curves. The engine was

setup for "My Driving Habits", mostly city driving, cruising and mountain curves. Turn the

key and she starts without hesitation, it can idle smoothly at 600 rpm's although I keep it

set at 800 rpm's. Throttle response is amazingly instantaneous. I only use 1st gear to get

started. Once in 2nd gear the fun begins, it can reach 53 mph at 5000 rpm, and 60 mph at

5700 rpm's, it is all torque and will push you back in your seat. This engine will easily rev

to 6000 rpm's without notice. Likewise, 3rd gear is another fun gear and no matter where I

am in the rpm range that power curve follows. In 4th gear I can slow down to 20 mph

around curves and have enough power to accelerate without downshifting. 5th gear (OD) is

really nice for freeway cruising, 70 mph at 3000 rpm. The T-9 Semi-Close gear ratio

performs flawlessly with a Supercharged MGB and is a perfect matchup for the street.

Street performance exceeded my expectations with exceptional throttle response by having

a broad, flat torque curve that pulls strong from idle, through mid-range and beyond. It is

the torque in the lower rpm for acceleration and then within the power band I spend the

majority of my time that makes this Supercharged MGB so fun to drive with that "Seat of

your Pants" feeling and driving pleasure.

 

Would Anything be done Differently:

  "No"!  I am more than "Completely Satisfied" with my Supercharged MGB. I would not

change this engine setup for anything. It has more than enough torque and horsepower for

daily driving. Being modernized and with all the comforts of a modern sports car really

makes this British Classic MGB very unique and lots of fun to drive. I have gained so much

knowledge from this "Do it Yourself" first time engine rebuild and restoration project. It

has given me the understanding of my MGB inside and out, resulting in many hours of trial

and error changes, which I enjoyed doing, to finally reach the point where all engine

modifications came together perfectly. I enjoy each and every moment when I get behind

the wheel of my Classic yet Modern MGB.

 

It is truly a pleasure to drive!

Happy Motoring...

I hope this website can help you with your MGB!

Best Regards, Ray Wyberski

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