I purchased a 1969 Plymouth GTX some years ago the motor work had already been done sometime in the early 90s it had a radical cam .30 bore the heads remachined and I'm not sure what all else was done as none of it was properly documented over those years. I am planning to add a 2 stage supercharger and blower with twins 600 carbs within the next two months. The blower is being done by supercharger USA and the carburetors by CNJ engineering and I am going to redo the motor to fit the specs they require for the system and what they need from me is a motor that has a compression rating between 8.6:1 to 9.2:1 to ensure that I shall be able to run the system on regular 92-93 octane pump gas. I am planning on tearing the motor down to at least the top cam and possibly the lower bottom and what I need to know from anyone that can help me is what all I will need to do to that motor to get in the required range for the system I will be operating. The system will be running between 5 and 6 pounds of boost ensuring that the supercharger maintains a 94% efficiency rating.THIS IS "NOT" BEING BUILT TO RACE... STREET USE ONLY .Any help on this subject matter would be greatly appreciatedy
No racing so I'm guessing this blower stuff is for looks only?Let's start here,Just for the compression ratio calculations you will need to know how your engine is built now, your cylinder head volume, the head gasket thickness and diameter, the piston deck height and the piston volume.Generally in boosted applications you would use a 2618 forged piston and piston clearances, rings & gaps for boosted engines.You'll run a camshaft with wider lobe separation to avoid blowing excess fuel and air out the exhaust during the cam overlap phase.
what? : engine, trans, rear gear. 5# boost an dual quads is more than looks, maybe +100 horse. measure some for 9:1 comp ratio, u may get that with the pistons u have. and if they are forged use them, and a cam around 228 degrees intake duration @ .050" and around 236 exhaust with 114 degrees lobe seperation.