camry90

How come I've not seen any body saying that you need to change to lower engin compression before going for FI?
Isn't 11:1 too high for any non direct injection engine to handle boost?

604gz

iTrader: (1)

hey camry90 i have been wondering that same thing but never questioned it? My G is twin turbo on stock internals always ran at 11.4 pounds now for the last 4 and a half years. my first car was a integra and the rule of thumb i was told while building my engine was lower compression is better for FI purposes

Glover998

iTrader: (1)

It's not high at all.. it depends on the boost you're going for .. stock compression is just fine for a stage 1 setups or as long as you keep the boost in a resonable level .. type of fuel is also play a role here.

However, changing compression to lower level will give you the ability to boost the engine even more = more power.

604gz

iTrader: (1)

Now i know why

G37Xtreme

Whereas 11.4 pounds of boost would be considered low for the Mitsubishi Eclipse which I think ran a lower compression 8.5:1 radio. IIRC, people would run up to 20lbs (maybe more) on these cars with massive turbos.

ANMVQ

iTrader: (13)

True I ran 24 psi on my stock 4G63 ( EVO 8). You'll never see that on a G with out 10k at least in the motor.

vqsmile

Besides the ability to run higher boost levels, running lower compression allows you to to also run more timing, which allows you to make more power. You can always boost a higher compression engine, but you'll likely have to pull some timing to avoid detonation, and hence will not be able to make as much power as you could have if the compression was lower.

Magowin

Yeah I ran 24 psi on my stage 2 Sti.

G37Stampa

Stock compression built turbo motor. Running 13.5psi for now on Q16