How do you tune a 1g for higher compression, ie 8.5:1

[90 GSX]

What timing, fueling, etc. changes need to be made with a higher compression 1g. I have an EPROM ecu and an afpr for tuning.

 

[tom04841]

Tuning should be the same. raise boost till you see knock, then back it down 1-2 psi. The goal is to run as much boost and timing as possible with no knock.

You can back down the timing a bit to run more boost.

But the general concensus is to tune for no knock.

 

[andymoraitis]

Have Jeff at DSM Chips change your chip for 2G timing maps if you want to run 2G compression. The 1G maps are more aggressive since the compression ratio is lower and you'll have a nasty time trying to maximize boost vs. timing on them. On the other hand, 2G maps peak at 16 degrees on the highest airflow map and are much more friendly to higher boost on pump gas.

Hope that helps,

Andy

 

[Kevin Jewer]

Wether it's 1g compression, 2g compression, EVO compression, or 9 or 10:1, I've found that the 2g curve works very well right out of the box for pump gas. My personal feeling is that compression ratio is a complete non-issue with these cars.