95-383

What is the max hp the fuel pump can handle at stock (46psi) pressure ??

mackeyred96

I'm still running a stock fuel pump and I dyno 360 rwhp.

EricVonHa

Who knows the factory fuel pump specs??? Take these facts into account: At WOT 1 gallon of fuel per hour is required per every 12 horsepower. You've got 300hp--> you're consuming 25gph of fuel. Also: Up your fuel pressure and down goes your overall flow capacitiy of the pump.

I'm with J.M. in that my LT-1 also dynos at over 400 "flywheel" horsepower. (Flywheel is what we're talking about in the formula mentioned earlier.) I didn't have to replace my fuel pump with my normally aspirated combination, but I did anyway. You know what they say about the ounce of prevention.... but seriously, many dyno pulls with data acquisition while varying fuel pressure never really ran the stock pump or injectors out of capacitiy or volume. Granted, I wasn't much over 400hp, but my A/F ratio is at a "power" perfect 12.5:1 across the board. If you're adding nitrous or a supercharger, the new pump is a new brainer. Internal combustion engine physics can be picked up at any library or just call Carroll Supercharging, and they'll graciously sell you a stack of manuals that contains all the basics.

So, back to the basic question... even if you're factory pump is capable at 45gph at 45psi and the typical 12hp per every gph applies... 45gph*12=540 max hp from this pump. Lotsa factors apply---> injector pulse width, fuel pressure under load and rpm and just exactly how capable is the factory pump?

SPD DMN

I dynoed 390 rear wheel with the stock pump. I have gone to a Walbro 255lph since though. Cheap and easy to change out.

Bob86ZZ4

I was noticing a power loss above 4500 rpm so I hooked up the fuel pressure guage and taped it to the windshield and went for a drive. You could watch the fuel pressure drop off above 4500. I converted from the stock pump to the huge Bosch sold by http://www.tpis.com. It was a easy swap and solved my problem. TPIS says the stock pump is good for about a 400 h/p engine. They sell this Bosch pump for $180. In the picture you can see the stock pump (it has a black foam wrap on it to quiet it down, so the pump is even smaller if you take that off) lying on top of the Bosch unit I put in. Quite a difference in size, and pumping ability. I took the old pump off it's mount and then used two big hose clamps to strap the new pump to the hard tube that the stock pump sits on. TPIS even includes directions. You do need to get rid of the stock pulsation dampner and use a piece of fuel line between the pump outlet and the hard tube. Feel free to contact me if you have any questions about this mod.


[Modified by Bob86ZZ4, 10:10 PM 10/31/2001]

95-383

Ok, so the stock pump should be good for over 400 hp. I haven't dyno the car yet after the new cam (similar to the hot cam), but it should be around 400 hp flywheel.