|
In Reply to: Where is the fuel pressure ... posted by Afshin-Switzerland on December 20, 2001 at 12:35:52:
It's not a good idea just to raise the fuel pressure, either, since then you will be too rich whenever you are not on boost (which is actually most of the time). The O2 sensor only has control over about 10% of the fueling, if I remember right? In order to increase boost from 7 psi to 12 psi, that requires (14.7+12)/(14.7+7) = 1.23 times as much fuel at the same AFR. Higher boost probably requires a richer mixture to help suppress detonation so say 30% more fuel as a ballpark figure. Since the flow rate through an injector rises as the square root of the pressure increase, you will then need (1.30)^2 = 69% higher fuel pressure. Stock is 2.5 bar = 36 psi (referenced to manifold pressure) so you will need 36*1.69 = 61 psi fuel pressure at idle... which will be way too rich at idle and cruise.
A rising rate regulator in series with your existing regulator (which is connected to the front end of the fuel rail and the return hose, incidentally) will work at modest boost increases (10-12 psi) if your pump and wiring are in good shape, and not affect normal operation at stock boost levels.
Just turning up the boost (more air) without adding more fuel is suicidal. Leaning out if it's overrich initially will make more power, right up to the point where you melt a piston, burn a valve, blow a head gasket or break a compression ring from detonation.
© 1997 -
2009
Jump Internet Inc. All rights reserved.
