I want to lower the compression in my 97 gsr. It's daily driven, and i want to keep a good driveability in town . Woud 9.1 compression make me loose a lot of torque before boost or it ain't that bad? would 9.5:1 be better?

(Of course in either case i'll be using forged slugs and rods)

 

i think its only like 3-5% power per point of compression that you lose. so from 10:1 to 9:1 you lose like 5 whp if you started off with 180....

 

go with 9.5 for a daily car only running 15psi... better around town and on the freeway...

 

is that 15psi on pump gas?? i hope not. in my experiences, 12 psi is about the max on 91 octane. reagarding the comp ratio... i say leave it stock (10.0 to 1) unless its a race only motor and you're planning on boosting 25 psi on it. a lower comp ratio will make your car really sluggish around town. believe me.. i know from experience... and its not as much fun as before the motor was built. once im into boost.. its a different story. but after doing it myself, i think the trade-off is well worth it. if you have the right fueling and timing, detonation will not be an issue.