Fuel pump size??

[BigBlockOlds]

Trying to determine what size pump I need for my 455 build and need a little help.
It will be a long rod 455 (offset ground 425 crank, 7.100" BBC rods) with multiport fuel injection going into my 1987 Cutlass. I have a Buick GN gas tank with a Walbro 255LPH intake pump.

My question is whether or not this pump will be able to supply a 550-600HP engine? I've read conflicting information on this pump and it has me a bit confused. One source says that you need 110GPH to support 600-650HP (the Walbro is around 67GPH) while another source says that the Walbro pump is capable of supporting up to 750HP @60psi.

Does anyone have any insight into this? I was hoping to use the stock tank and in-tank electric fuel pump for ease of plumbing. Is there a larger in-tank fuel pump for this application?

Thanks!

[Doug F]

YOu should be just fine at 45 PSI.

600 HP x .5 lb/hp/hr = 300 PPH / (6 lb/gal)= 50 gph

750 at 60 PSI is not realistic. Too much of a stretch.

I run one on mine at 45 PSI and I am about 630-640 HP and don't lose 1 PSI at WOT.

I've got the flow curves of the pump at work.

Also 12v won't cut it, you need to make sure you have 13+v to get full potential of the pump at 650 HP.


It is all math and then you take into account a "safety factor".

[BigBlockOlds]

Thanks for the reply.

As for voltage, I have what they call a "Hot Wire kit" for the fuel pump in question. I assume the purpose of this kit is to provide proper voltage to the pump?

Also, what size feed line should I be running? I had planned on running 1/2" hardline from the tank to the engine but if I'm planning on 600HP, do I need to step it up to 5/8"?

Thanks,

[Doug F]

I'm running 3/8 (-6) everywhere and have a good gravity feed and have no problems. I'd rather have a 1/2 feed but I've had no issues. A -8 is good to 1500+ HP usually at 43 PSI.