Fuel pump needed to run a LS3 or LS7

[try2pas]

Does anyone know the PSI and GPH needed from a fuel pump located in the gas tank to feed a LS3 or LS7 engine?

 

[c4c5specialist]

HI there,

The pump MUST feed at least 65 psi and over 2 gallons per minute.

Operational pressure for the fuel system when regulated is 55-61 psi.

Rememeber that on Corvette, these pumps are internally regulated within the fuel pump module assembly.

Allthebest, Paul

 

[try2pas]

Are you saying that the fuel pump itself, and not a separate regulator, regulates the fuel pressure and the gallons per minute that it puts out? What after market fuel pump would then fit these requirements of self regulation and the 61 psi and 2 gallons a minute?

 

[Hib Halverson]

What Paul was trying to tell you is that all C6 Corvettes have the fuel pressure regulator and the fuel filter built into the fuel pump module which is inside the driver side fuel tank.

If you'd explain a little bit about what you are trying to do, maybe someone can be of more help.

 

[try2pas]

I have a 1980 corvette that I put a LS3 in it and someday would like to put the LS7 in there. I have a 4L70E trany and a 373 rear end. It seems to go good at lower speeds but seems to fall off say at 70mph on. I had it tuned and the guy said that it wasn't getting enough fuel at high rpms. It has a Delco EP381 fuel pump in the tank and a filter, and maybe it's a filter regulator outside the tank. The EP381 puts out 61 psi and 41 gph or about .68 gallons a minute. I heard that a LS7 wants the 61 psi and about a gallon a minute. Someone said to put a Stealth 340 in there that puts out up to 90 psi and 1.5 gallons a minute or 90 gph. So I am just trying to find out what, indeed, I should put in the tank to pump my gas to the LS3 and later a LS7(the ultimate corvette engine in my opinion).

 

[c4c5specialist]

HI there,

That fuel pump should be easily adequate for the LS3, there is something else wrong.

Allthebest, Paul

 

[Hib Halverson]

I have a 1980 corvette that I put a LS3 in it and someday would like to put the LS7 in there. I have a 4L70E trany and a 373 rear end. It seems to go good at lower speeds but seems to fall off say at 70mph on. I had it tuned and the guy said that it wasn't getting enough fuel at high rpms. It has a Delco EP381 fuel pump in the tank and a filter, and maybe it's a filter regulator outside the tank. The EP381 puts out 61 psi and 41 gph or about .68 gallons a minute. I heard that a LS7 wants the 61 psi and about a gallon a minute. Someone said to put a Stealth 340 in there that puts out up to 90 psi and 1.5 gallons a minute or 90 gph. So I am just trying to find out what, indeed, I should put in the tank to pump my gas to the LS3 and later a LS7(the ultimate corvette engine in my opinion).

I think you're just wasting time worrying about specifications.

If the person who wrote the calibration for the engine says your running out of fuel, the first thing to do is verify that's true.

You can do this on the chassis dyno or you can road test. You need to see what the fuel pressure is doing during wide-open-throttle operation at the top of the mid-range and, if it's ok there, you want to test it high-rpm. You want to be careful here because if the engine is lean at WOT high rpm, you don't want to run the engine too hard. Start by running the engine to about 5000 rpm with high part throttle while watching the gauge. If you see a significant pressure loss, you have inadequate flow caused by either a restriction downstream of the measuring point, an inadequate pump or the wrong FPR. If you don't see any decrease, accelerate again this time with more throttle opening, and so on and so forth.

To do this test you need to either install and electric fuel pressure gauge in the cockpit or obtain a digital fuel pressure gauge such as the Waekon "Universal Digital Pressure Gauge with Remote Readout. The last alternative is to use a mechanical fuel pressure gauge with a long hose and the gauge itself taped to the windshield or tie wrapped to the wiper arm. If you're using a mechanical gauge DO NOT run the hose into the interor of the vehicle.

Keep in mind that the fuel pipes and hoses on an 80 are sized for an engine of about 200 hp.

You've installed an engine with 430-hp and you're thinking about putting in an engine with 505-hp.

If you are using any part of the the stock 1980 fuel plumbing–the stock fuel pipes running from the tank to the engine compartment, for example– it is likely the entire fuel system, from the tank forward is not capable of the fuel flow you need.

 

[try2pas]

I have a 3/8" fuel line from the tank to the engine. Isn't that big enough? I think I have a fuel filter/regulator outside the tank. I am going to replace it as I had a fuel pump lock up 2 years ago with metal filings stopping the gerars. Would I be better served by a C6 fuel pump/filter/regulator? Is my pump the one I want for a LS7?