I'm having some newer/better pistons put into my ls1 - and the question popped up: lowering the compression? I've heard that lower it down to 9-9.5 helps protect the engine, while also giving it one hell of a hit when squeezing. I wasn't 100% sure, so I thought I'd run past some of you guys.

KASR

 

contrary to somes belief, when using nitrous, the CR is not a issue. you can go as high as you want really, although i would just stick close to stock if you're planning on driving the car alot.

the only real need to lower CR is when using a FI PA. when slapping on a blower or turbo, usually people will run 8:1/8.5:1 CR. and even in a bosted application, you COULD run a higher CR, you just wouldnt be able to run as much psi. the less CR you have, the more boost you can run. typically, a lower CR motor with alot of boost will make more power than a high CR motor with a little boost.

but with a n2o motor, lowering the CR will not make a difference. if anything, you should raise it a little.




jon

 

It all depends on what size shot you're planning on running, if you feel like running race gas, and how often you plan on running N/A vs spray. If you want to run a big shot on pump gas, then yea, a little less copression than stock would be benifical. If you're only looking at 100-150 shot on pump gas, you can get away with stock or a little higher compresion by pulling out some timing.

Also, if you're not planning on running on the juice most of the time, then you probably wont like 9.-9.5 compression, since you're not going to be making the same power N/A as a higher compression motor - Kinda like running a blower motor with no boost.

Course there's a lot to be said about going with lower compression and being able to squeeze a 300shot on 93 Octane Torque monster

Just figure out what you want from your motor and how you plan on running your car before you pick your pistons (or cam for that matter)...

 

i wouldnt worry about the copression...if your like the everyday joe and u drive the car on the street and take it to the track once everywhile and will spray up to 150....then thats not an issue