high compression on a turbo engine like 9:1 means that by the time the turbo spools up and is dumping the extra fuel and air in the engine that you are just about at 10:1 now. pretty high if it isn't a race motor. and that is also if you are only running maybe about 6-7lbs of boost. that is alot of extra added stress on a motor that doesn't need to be there. normal turbo engine's are below 9:1 (even though it's not terribly bad as long as the motor is built stronger) because of the added compression of the turbo when it spools up, plus if you have lower compression then you can boost up alot higher and make alot more power than someone who is running 9:1 comp.

 

all very true. just i thought about doing this route as the most fun. when it blows it it blows. time to build something else. i think today most new cars that have turbos are acutally running 8:1 comp could be wrong

 

Indeed... 8:1 to 9:1 on turbo cars these days. But 25+ years ago motors were designed differently. The main differences are head flow & fuel management.

 

we got a all cast iron block an inline setup and overall, a strong motor other than the studs that can expand. aka ARP time and metal head gasket. and there are MANY cars that run much higher compressions that are turbo. and most cars are 8.5:1 that are turbo. soooo my 8.8/9.0:1 compression ratio isnt really going to be to detramental, its ALL about tunning and keeping the air cool. also, forged internals are very helpful.