As you can tell by the sig Ive done some major changes to my car and plan more. I plan a lt4 hotcam this summer and a set of heads (still debating) anyways how much HP can i see from my stock intake pump? I want to run nitrous but i decided not to until I change the pump.

 

I'll take a whack at this: around 230 hp is the limit.

Why? Because at least three people with Bcars (Caprice) using TBI LO5s have been stonewalled at 15.5 to 15.7 sec at 85 to 87 mph in the quarter mile when using the stock Caprice TBI-intended pump. Those timeslips, btw, equate to around 230 fwhp.

Those cars have varying levels of mods, but one has headers, cam, intake, duals, etc so it should be running under 15.0. I'm convinced that insufficient fuel (TBI tuning) is one problem, but even with a boost in the fuel pressure (which makes the car run too rich on the street, but should be a good-enough track band aid) doesn't result in any improvement.

So I conclude that the stock pump just can't provide enough volume for more than around 230 fwhp, and I've also heard that the stock pump also doens't like (or wasn't designed) to pump into a FPR set for much above 14 psi.

So you'd be advised to install an LT1 pump (it's a direct swap), or the aftermarket equivalent. The LT1 pumps can supply enough fuel to make around 400 fwhp on a modded engine, so volume delivery is more than enough for you and the pumps are designed to pump into a FPR set for around 43 psi at WOT, so in a TBI application running 12-15 psi, it will also be no problem. FWIW. - Ken

 

well Im not running 14psi...im running 6. I have a mallory fuel pressure reg changing my ~12 to 6. So maybe It can support alittle more on a carbed car? I know a couple people with pretty built 350s and the stock pump. I want to get a walbro 255lph soon tho...just such a pain to change the pump.

 

I guessed, with info to back up the guess, that 230 hp would be the limit. It won't matter if you run a carb or TBI, and it won't matter if you are running 6 psi instead of 11-13 psi. Power is a rate of work, and the engine power is a rate of work that depends directly on the rate of fuel volume from the fuel system. The stock pump won't reliably support more than 230 fwhp because it can't provide enough a volume rate any higher. Also keep in mind that the above number was based on cars that each had at least 50k miles on them (and their orig stock pumps).

 

<--- using stock fuel pump when running time in sig pump now has 160k miles on it and is still working BUT is definatly a bottle neck. Figure around 300hp flywheel to get my 3600 tank down the 1/4 at 102mph.
BTW, a stock fuel pump's HP support is very dependant on fuel pressure. If I was running small injectors I would need high fuel pressure to flow enough fuel hence more work required by the fuel pump VS large injectors and not nearly as high a fuel pressure. So yes a fuel pump can support more hp depending on how much fuel pressure you run. Going with 5psi for a carb vs 80psi on some monster peak&hold injectors is a big difference in how much fuel can flow from the tank to the engine.
Happy medium , pay $30 for the 0-30psi fuel gauge from Summit and get the inline t-adaptor (1/8" NPT fitting) then run it to the hood and splice into the upper (supply) flex line and run the lines up to the gauge so you can watch the fuel pressure in 3rd gear with high speed WOT. If fuel pressure dips then you've got issues, if it doesn't, you're good for more go power.

 

I'm using the stock tbi pump with 214,000 miles.

I'm going to take a wild guess and say i make more then 230fwhp though

 

My stock fuel pump kept me door to door with an LS1 SS Camaro one night. Just my .02

Tom