I'm a carb guy. I haven't messed with much injected stuff. I have a stock '87 Turbo coupe as a daily driver. I was wandering what the fuel pressure should be. Do you set it with vacuum connected or disconnected? What kind of fuel pressure should I have under boost? I wouldn't mind hopping this thing up just a bit, but I want to know what's going on before I burn something up. It seems to fall off or feel lazy above 4500rpm.
Well factory fuel pressure is around 35-36 psi I think...I assume you have an aftermarket regulator? You're supposed to set fuel pressure with the vac hose disconnected. Is it doing anything unusual when it feels like it falls off?
It's probably falling off a bit because the IHI turbo is small and doesn't breath real well up high. Fuel pressure is ~32-34psi line disconnected, ~38-40 connected. Fuel pressure should raises 1:1 meaning 1psi boost adds 1psi fuel pressure. So if you run 15psi you should have ~53-55psi at full boost.
Okay. Thanks. Yes, I have an adjustable regulator and gauge. I will set it and see what she does. When it falls off it just feels lazy like it quits excellerating. Mid range it nice and strong. (Between 2500and 4500rpm.) After that it ain't got much. I thought it should have more up high.
Well that could just be the nature of the beast. Everyone told me that stock turbo engines fell off at high RPM's especially with the IHI turbo, but I never thought mine felt all that bad. I guess I should ask, how bad does it fall off? I mean, does it feel a little soft or does it fall on its face?
It feels really nice between 2500 and 4500. After 4500rpm, it keeps excelleratiing, it just doesn't pull very hard. It seems that if I go ahead and shift and get the Rs back down in the 3000 range it pulls again up to 4500ish. It just doesn't seem right. I did set the fuel pressure as recommended. I'm at about 32-33# with vacuum disconnected. I get about 52-53# under boost.
