i'm going to get endyn pistons at the end of the week and need to know what is a good compression to run? I was thinking more on the lines of 9.5:1 cause i still wanna have a little on the low end what do u guys think?

 

Anywhere from 9.0:1 to 9.5:1 is good for the street.

 

Depends....are you going NA, turbo, or NOS?

 

the lower the compression, the bigger the tuning window. the higher comp. you run, the more power you can make at a given amount of boost.....but your also running a higher risk of going boom.

if you run high comp w/boost.....please be a good tuner.

 

i wanna run a turbo 10psi daily and 15 psi at the track

 

For that boost, I would run 9.0:1 myself. 9.5:1 is ok, but it narrows the error margin considerably.

 

what would be the most reliable and most efective compretion on a turbo car?

 

that ???? will be debated forever. no one on here will be able to give you an exact #. its all up to OPINION. there are (turbo) import drag racers making 600 hsp to the wheels w/ comp ranging from the high 8's to 11's. most make it in the 9:1 - 9.5:1 range.

 

Life is a comprimise. Power or reliability? There are numerous people on this board that run with 10:1 cr all day long and have no problem. Keep in mind though, that most, if not all factory force-fed cars run <9:1 compression.

Take your pick. Lower compression will allow you to make more mistakes before you go boom. Higher compression will sig narrow your tuning window, just the the posts above this said.

Tom

 

im going to run with stock CR (10:1)
starting with 4,5psi and raise the boost when i have possibillitys to fine tune.

 

Well if you are running a standalone and larger injectors and plan on tuning the engine on the dyno immediately after installation, then yeah you can run high compression and boost. My friend was running 11:1 with his JDM ITR engine and Drag kit. We had 550cc injectors and Motec standalone with water injection, tuned running around on 10lbs daily driven. With the right tuner, water injection and know-how anything is possible. It has been a year since we turbo'ed his hatch and it is still going strong. He runs consistent low 12's, high 11's with somewhere in the neighborhood of 300whp at 10psi.

The best street-driven compression ratio would be 10:1 though. You would still have some low-end for street driving and have the ability to make some serious power from the high-compression. Just remember to reduce timing (reduce cylinder pressures) and enrich the mixture to about 12:1~12.5:1. You would be set to about 10-12psi on pump gas.

 

how about 9.8:1 c/r..this should leave a pretty big open window for tuning..