Just picked up a vette with a Procharger on it.

Had a few questions. I come from a small displacement turbo world, I find things are a bit different here.

The stock FPR was leaking fuel out of the vacuum nipple. I replaced the FPR seal/spring/piston. Is this a common issue?

Also, the stock FPR had the vacuum line disconnected. Wouldn't this have to be connected to reduce fuel pressure in vacuum? Also, does the stock FPR not pressurize from a boost signal? (eliminating the need for the ATI FMU?)

Also, in the ATI manual I have, it basically says to wire the fans on all the time. The previous owner decided to wire a manual switch. Leaving the switch on at all times keeps the water temp gauge at about 135 (just under the first notch) Is this the intended operating temperature?

Also, I'm getting some surge under extremely light loads. Ie. If I rev the engine and hold it at 2k, it oscillates. Or if I need to drive at 15MPH, the car surges consistantly. Is this because of the drag of a supercharger? (didn't really have the same type of surge with turbos)

What type of pistons are on the L98 (1990 vette)? If properly tuned how much boost could she take?

Apparently I have a 7lb pulley on, but realistically see 5lbs at WOT, is this normal?

Thanx for any thoughts! Still adapting to the vetter world, but its a lot of fun having all this torque on tap!

 

This is a common issue with a forced induction type appliocation and even NA applications. Rememeber, your car is now 15+ years old, and that is a lot of cycles for a small buna rubber diaphragm.

The line was probably disconnected because of raw fuel circulating into the intake causing an overly rich condition at idle. The stock FPR will adjust the psi down by ~4 psi at an idle and then corrects 1:1 based on boost. You would probably see ~47 psi under full boost (based on the psi quoted in this post). This is not enough fuel psi for stock injectors and a ProCharger. The ATI FMU will need to stay as long as you are using factory injectors and the factory computer.

Previous installs that I had done left the computer controlling the fan. I would follow the owner's manual, but 135°F is way to low. Do you live in Alaska?

This is a tuning issue. Get the car to someone with a dyno, wideband and chip tuning capabilities. This will reap significant rewards.

I believe these were hypereutetic pistons. The amount of boost that your engine is capable of is entirely dependent upon the tune. With a poor tune, one could destroy an engine with just a few pounds of boost. With a good tune, these engines can be made to live a long time at 12 psi. Though eventually, the ring lands will let go.

Perfectly normal for the ProCharger world and the 8 psi kit. If you had the 12 psi kit, you would probably see 8 psi. You should be glad that your engine is near stock, as my first ATI install yielded 2 psi on a modified '87 vette. I eventually got that to 12 psi (on a custom pulley that ATI did not recommend).

Cheers,
Aaron

 

Thanks for the response, let me clear up a few things and see what you think.


Now that the diaphram is repaired and raw fuel won't leak back in, should I reconnect the line?


The stock FPR is actually a stock diaphram+spring with an aftermarket adjustable cap. (BKS?) It has basically come unadjusted (screw entirely out) Also, the injector system has 36# injectors and a chip modified by blowerworks. Why did ATI not decide to have the stock unit removed completely if it wasn't flexible enough? With the adjustable cap, can the stock diaphram maintain the pressure? What about just replacing both with a return line and an aftermarket AFPR?


Actually I purchased the car in Maine and have been driving it cross country back to southern california. When the ambient temps are ~90, with the fan on the stock water temp sensor needle sits at the first notch. 140 degrees? I'm not sure where the stock sensor is located, or how accurate it is. (also, i'm assuming the water temp sensor reads as, 100, 140, 180, 220, 240 as far as the notches are concerned)

If I click off the fan and its 75ish outside, the temp will sit right at 140. (cruising at 75mph)

Thanx again!

 

hmmm, something doesn't jive about the advertised water temps. With those temps you are not burning off any contaminents from the oil. Either you've got a super efficient cooling system, or the temp sensor and/or sender is inaccurate. What is you oil temp?

 

Absolutely. This is the way the system is designed to work.

The reason the screw is all the way out is probably because the engine was running to rich at an idle. If the motor is basically stock, just with the S/C, then the 36 #/hr injectors are really too big. But they can be made to work with adjustments to the chip (i.e. Blowerworks chip) and adjusting the AFPR. The FMU can not be used by itself (w/out the AFPR), as it has no ability to open further based on vacuum. At an idle, the FMU is full open, and the AFPR is near full open. At atmospheric (WOT, no boost), the AFPR is relying upon spring psi to restrict the fuel return, the FMU is wide open. As you start seeing boost, the AFPR starts adding psi on the backside of the diaphragm, effectively increasing the spring action in the AFPR; the FMU is starting to pinch closed.

I agree with Dave's comments below, something is not reading correctly. You can verify the coolant temp based on the oiul temp indicated.

Aaron

 

If i'm climbing a hill, it can increase to 180ish. If i turn on the AC, it increases to 180ish. In town, with the fans on, it can get over 190. I'll have to check the sensor wiring.

Unfortunately, the oil temp sensor is not working at all.

Also, on a completely different note. Does the supercharger make a gear mesh sound at low RPMs? (1k-1.5k) When I accelerate slowly in 1st gear or travel slowly at that RPM range, it sounds like a gear mesh (almost like a grinding sound, but smoother and not as loud). I didn't know if this was normal, or maybe I'm getting some exhaust rubbing due to low RPM resonance. (or something else entirely?)