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MGB Supercharging MGB MKII with high compression ratio

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al1978

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We want to supercharge our MGB but at the moment we have a fairly lumpy cam in it & high compression ratio or 9.5:1
Anyway we have the original cam to put back in but dont want to bother changing the head etc. Has anyone supercharged one of these motors with high compression? I have head some cars like Volvos can be superchargerd or turboed with 10:1 ratio. We only want to run about 6-8 PSI
 
Yea only 6 or 8 till he hears that varooooom sound to his right. Then it's turn up the boost to 12 dear and lets show this rice burner what we got.

Yeeee Haaaw
 
The 9.5 compression ratio shouldn't pose a big problem for supercharging. My Miata has about a 9.0 to 1 compresion ratio and is blown, and some of the later Miatas have 9.5 to 1, and they can be supercharged. The real problem is ignition timing. If you back off the timing so it won't ping while in boost, you will lose a lot of punch when not in boost. Typically, timing will have to be retarded by about 4-8 degrees (depends on the engine) if you run about 6 psi of boost. The best solution is to have some sort of timing retard that takes affect when in boost. There are some electronic systems out there that will do just that. There will be a vac/boost hose going into the electronic control box, which will re-adjust timing accordinly. You might try to see what MSD offers that would work.

Edit: This MSD unit should work OK for this application.
 
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