Compression Ratio Question
09-18-2004, 04:46 AM
#1
Compression Ratio Question I starting an LT1 355 blower motor buildup. Here is what my combo is going to be. A 4340 forged 3.48 inch stroke crank with Forged 5.7 inch H beam rods, 4 bolt studded mains, studded heads, JE extreme duty 22cc inverted dome pistons with Speedpro rings and Hellfire ring combination. I have got band new bare AFR 210 LT4 heads that I am going to have fully ported (Hopefully AI) with custom HR blower cam matched to the heads, LT4 intake with ASM Monoblade. Here is my issue, the heads right now are 74cc unfinished and will probably be close to 76cc when finished. With the JE piston that I have chosen, their chart shows 7.8 to 1 compression ratio with these heads. I am planning on running about 15 pounds of intercooled boost. This is a pretty low compression ratio, I want to be on the safe side and build the motor to hold more boost than I'm going to give it. My question is, will this low compression ratio hurt my horsepower output (compared to say 8.0 to 8.5 to 1) and will it hurt low end power? I just didn't know if the low compression ratio would kill the streetability?
09-18-2004, 04:56 AM
#2
Originally Posted by n2oblkz
I starting an LT1 355 blower motor buildup. Here is what my combo is going to be. A 4340 forged 3.48 inch stroke crank with Forged 5.7 inch H beam rods, 4 bolt studded mains, studded heads, JE extreme duty 22cc inverted dome pistons with Speedpro rings and Hellfire ring combination. I have got band new bare AFR 210 LT4 heads that I am going to have fully ported (Hopefully AI) with custom HR blower cam matched to the heads, LT4 intake with ASM Monoblade. Here is my issue, the heads right now are 74cc unfinished and will probably be close to 76cc when finished. With the JE piston that I have chosen, their chart shows 7.8 to 1 compression ratio with these heads. I am planning on running about 15 pounds of intercooled boost. This is a pretty low compression ratio, I want to be on the safe side and build the motor to hold more boost than I'm going to give it. My question is, will this low compression ratio hurt my horsepower output (compared to say 8.0 to 8.5 to 1) and will it hurt low end power? I just didn't know if the low compression ratio would kill the streetability?
Talked about CR in here.
https://ls1tech.com/forums/forced-induction/202685-how-much-boost-before-pump-gas-will-not-work.html
1071, 15, 15lbs, 78, 80to, 85, blower, boost, combustion, comp, compression, horsepower, ls1, ompression, pounds, ratio, safe
