Fuel pump size questions...

[BigBlockOlds]

Hello everyone,

This question doesn't really purtain to a Buick but it does involve Buick parts.

What I have is an '87 Olds Cutlass that I am currently in the midst of doing a frame-off resto on. It has a 455cid Olds engine that I've converted over to EFI and a stock Buick GN tank with the filler neck from an Olds welded on.

I had planned on running a Walbro 340 pump but I'm concerned with whether or not it will be able to keep up with the engine. I'm shooting for the
550-600HP mark running 1/2" hard line from the tank to the fuel rails.

I've seen conflicting information on what the 340 can support horsepower wise and figured this would be the place to ask.

Also, is there any other options out there for the GN tank without having to go to an external pump? I've seen the dual Walbro pump setup but I don't know how that would be made to work with a N/A car. I doubt I would need the fuel that two pumps would be putting out.

Any information and help is greatly appreciated.

Thanks!

 

[turbofabricator]

First question is what EFI system are you using? If it's port EFI then the Walbro 340 single pump will feed 550 hp very well. A single 3/8 line will also work good to 600+ hp. Grumpy has run a 10.1 with a single Walbro 340. (and alcohol injection) If you need more fuel, then a double pumper will help, but both pumps feed through the single 3/8 line coming out of the sending unit. You can fab a new sendng unit like I did, or I "might" be persuaded to make more. http://www.turbobuick.com/forums/general-turbo-buick-tech/213340-complete-new-fuel-system-parts.html If you want a reliable 600+ then a dual pump is probably needed. Or you can go with an Aeromotive/Weldon pump and install a 5/8"-3/4" pick-up in the stock sending unit. I have a sending unit that I was working on with a 3/4" outlet for a "sucker" line to feed a big external pump. But, I think that a single Walbro will be fine (but on the edge) for a NA 600 hp engine.

 

[BigBlockOlds]

Thanks for the help. Yes, the EFI is multiport. Picture of the engine in progress:

If a single Walbro would work, then thats what I will stick with. Would there be any problem with going to a 1/2" feed line? Would this cause any pressure loss with the Walbro making it less effecient?

Another thought I had looking at your pictures from the other thread is if you could run the dual pump setup with two regulators so that essentially, one pump provide fuel to just one half of the engine? Obviously this makes things much more complicated, plumbing, electrical wiring, etc. but would it be a viable solution if I wanted to go with more horsepower later?

Thanks a bunch!

 

[turbofabricator]

Thanks for the help. Yes, the EFI is multiport. Picture of the engine in progress:

If a single Walbro would work, then thats what I will stick with. Would there be any problem with going to a 1/2" feed line? Would this cause any pressure loss with the Walbro making it less effecient?

Another thought I had looking at your pictures from the other thread is if you could run the dual pump setup with two regulators so that essentially, one pump provide fuel to just one half of the engine? Obviously this makes things much more complicated, plumbing, electrical wiring, etc. but would it be a viable solution if I wanted to go with more horsepower later?

Thanks a bunch!

You'll want to keep things simple and use a single large aftermarket pressure regulator that can handle the fuel volume. Professional Products has a nice new one with a 7/16" internal passage (stock GN regulator has a .174" internal passage) They are available from naparts.com

 

[BigBlockOlds]

Cool, thanks for the help.