Bambam7

A mechanic told me that a good rule of thumb is that while adding boost- you NEED to add 1.5 psi of fuel presure per every 1 psi of boost.
This somewhat makes sense to me, since you could theoretically (if you were boosting 30 psi) drastically reduce the fuel going into the engine, since the relative pressure difference would only be like 5-10 psi..
I am only doing 10 psi.... the increase in pulsewidth by my S-AFC should definatly be enough right??

He may be talking about increase fuel by means of ONLY an adjustable fuel pressure regulator- and not using any kind of other correction when adding a turbocharger...

BLUE TII

iTrader: (9)

Yea, I think he is referring to the "old school" way of adding fuel to a turbo-ed car. Vary the fuel pressure the injector sees to flow more fuel under boost w/ rising rate FPR. You should have it covered adding fuel w/ S-AFC. You just up the pulsewidth of inj.- just don't exceed a safe duty cycle ~80% I think? Ian

NZConvertible

Your stock FPR already increase fuel pressure if you increase boost. These keep fuel pressure a fixed amount (~40psi from memory) above manifold pressure. So at idle (say 16inHg vac or -8psi) you have 30-35psi fuel pressure, at 10psi boost you have about 50psi fuel pressure.

HAILERS

If you have a stock fuel pressure regulator and a fuel pressure gauge, put the fuel pressure gauge in the fuel line and put a pressure pump such as a MITTYVAC on the vac/boost nipple of your fuel pressure regulator. Start the car if you want, and apply ten psi gradually to the vac/pressure nipple on your stock fpr. What I get is, is a fuel pressure reading of fifty psi on the fuel pressure gauge. SAme thing when driving with the fuel pressure gauge in line and on full boost. For some reason or the other, other people do not get the rise in pressure in the fuel line. I have no idea why they don't. You should if its a stock pressure regulator. EDIT: Its an incremental increase in pressure, not ZAP DIGGITY fifty psi. Gradual increase to fifty as pressure is increased at the nipple on the fpr. Total stock unit I am talking about from fuel pump to fpr.