Well I went to the Dyno today and the car did 691 RWHP but I was runninf out of fuel at 4500 RPM..........Im running 60 Lb. Injectors with Racetronix Fuel Pump and Kenne Bell Boost A Pump on a 383 with a D1SC. My fuel pressure drops into the low 30's at 4500 RPM so I believe Im running out of fuel. Should I go to an external fuel pump or go to leingertfilter fuel pump...........


Please give me advice on this.

 

You'd be alright if you converted to a return style fuel system. The Racetronix and LPE fuel pumps are basically the same. For the price of a bigger returnless pump, you can do the return system.

 

Mike,
I would add a return and a regulator...

The problem that you are having is that the regulator exists in the fuel filter now.... So if your engine is drinking more than the line can supply 'after' the regulator; then you will see a drop in fuel pressure.

If you convert to a return style system, then the regulator goes after the rails; hence pressuring the system from the pump to the regulator (supplying enough fuel to the rail)...

gook luck.

 

Mike: I would check out the voltage at yor fuel pump when the pressure switch for it is shorted. The simplest thing is to simply start off with a jumper across the switch and verify your voltage goes to 17+ Volts at the fuel pump. Your 0-50% pot should be set to 50% ,or simply replaced with a wire , which will give you max voltage. I beleive the 99 has a return fuel system. I question your numbers from your post, if you have let's say 35lbs at your fuel rail and aproximately 15lbs of boost, that only leaves 20lbs of pressure across the injectors. You will not be able to make 691 RWHP with 60lb injectors and 20lbs across them. Something about your data seems wrong.

 

I agree if you don't have a return style, boost reference fuel system... that SHOULD solve your problems.

That is a huge drop.

Mike I have all of the part numbers too for the conversion if you want them. The stage and power level you are at.. you may want to consider talking to ECS about their high HP fuel system.

 

PM sent

 

I was there for those dyno runs yesterday and Mike has already converted his fuel return system to the 97-98 model. My setup to his is the same except for 3 things 383/346 auto/MN6 and racetronics/LPE fuel pump. With him having bigger cubes or voltage drop which we did not check or is the racetronics going out are what we are looking at so far, and maybe he needs 75 lbs injectors?

 

I've heard that their a b!!ch to tune and dont have very good low speed driveability.
I agree with "glennd," your racetronix might be crapping out. But its not very likely, cause this has only happened since you went to the smaller pulley and upped the boost.
I think its time fr a "Mild" upgrade from ECS..

 

Well Im looking at the Dyno Graph right now..............and its 691.20 and 636.15 Torque.

 

I dont mean that I agree with "glennd" abut your numbers. I know your power is accurate. I agree that it "Might" be your pump..

 

Two words explain it: Alky Injection.


Mike (I know we already talked on the phone last night, but I will throw my 2 cents in here as well.

First off. 690RW with a D1 through an a4 is impressive. You should be in the 9s for sure.

As far as the fuel system goes, A healthy version of your setup should supply enough (especially since you are running alky). The fact that you got a dyno pull with 690 and 35psi of FP says a lot. If you road raced the car I would suggest looking into a surge tank external pump setup, but for what you do with it, the intak should be enough. The cost of going with a custom external setup is pretty insane, not to mention all the problems you can run into (just ask diynoob or read this recent thread http://forums.corvetteforum.com/show...49&forum_id=86).

Bigger injectors are not the place to start for sure.

I would first check and make sure the BAP is working. After that I would try putting in a new pump. The fact that your pressure dropped that low tells me that something is wrong (it is not just that the smaller pulley pushed you over the edge).

The earlier racetronix pumps seemed to have something that made them fail often. They now use the same exact pump as the LPE, so I would try the current version of the LPE or racetronix.

 

I think you need to upgrade the fuel system. Stock fuel lines with a dinky Walbro pump is only going to take you so far.

Mark

 

I never Road Race the car......

Thaks for all your help Bro!

Ilet you know what happens after Autorama

 

Going to a bigger injector will just make the fuel pressure problem worst. If you are losing pressure, that means the pump isn't able to keep up with the injector flow requirments. Either the pump with the boost-a-pump can't supply enough fuel (from too small or starting to fail), or there is a restriction somewhere. Check for kinks, clogged fuel filter, etc..

 

Going to a bigger injector will just make the fuel pressure problem worst. If you are losing pressure, that means the pump isn't able to keep up with the injector flow requirments. Either the pump with the boost-a-pump can't supply enough fuel (from too small or starting to fail), or there is a restriction somewhere. Check for kinks, clogged fuel filter, etc..

Tech note from Racetronix:

Technical note:
The Racetronix fuel pump in this system is capable of supporting apx. 600RWHP @ 0.5 BSFC @ 58PSI (400KPa) using factory lines. In early model C5's with rail-mounted fuel pressure regulators the above HP support can be achieved.
If a pump voltage booster is added 700RWHP+ can easily be supported. (at this HP level modified fuel rails should be used to prevent deadheading)

Late model C5's with the returnless rail system will not be able to achieve this level of HP support with the fuel system alone.
This is because the point of regulation is at the back of the car. The location of the FPR does not allow it compensate for line
pressure drop even though the pressure is stable at the back (regulator location). There are two options to get around this problem.
First is to convert the system to a rail mounted FRP return type (best). The second option is to install a pump booster which is
activated at the point where rail pressure starts to drop. The boost in fuel volume overwhelms the regulator / return line thereby
increasing the fuel pressure at the back of the car which translates to higher pressure at the rail. We recommend the MSD unit for
FI applications as it ramps the voltage based on manifold pressure. This prevents a short but abrupt fuel pressure spike which
causes the motor to hiccup from brief over-fueling. If you are using an instant-on N2O system then the KB BAP can be considered as well.

Please understand that this is not an issue with the Racetronix system but rather a design limitation of the factory configuration.
Racetronix is working on a plug & play solution to address these problems as well as the new 2003 C5 module. No ETA is available at this time on these solutions / components.

2003 C5 Corvettes can be checked for compatibility with the Racetronix fuel system. If your access port for the fuel module can be seen in front of the driver's side rear tire (under the car) then this system will work. If it is not visible then you have the new type of module which goes in from the top of the tank. The Racetronix system is not compatible with this fuel module / system. If you are not sure please have a qualified person check before ordering your system.

 

I will call Arnold tomorrow and let him know....thanks

 

97 & 98 not 99

 

Mike converted his to the 97-98 system, along with the BAP and Racetronics fuel pump.