Sxynerd

I totally forgot about the fuel system, lol. So now I have to decide what to do there.

Anyone know what a 255 pump will actually support with a return style fuel system? I have 60# injectors and aftermarket fuel rails.
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amoosenamedhank

I actually was talking about this the other day with my tuner. I asked him what I should run for a fuel set up. I don't remember the exact number he said the 255 was done but I was asking about 500+hp so assume you should upgrade.

I'm looking into an Aeromotive A-1000 fuel pump, with a sumped tank. I'm going to run new lines. With a -6AN feed and a -8 AN return. You're probably going to need aftermarket rails as well.

cliffyk

Here are some great numbers for Walbro's pumps.

Both the standard and high pressure pumps can deliver at least 50 gal/hr (317.5 lbs/hr of premium fuel) at 43.5 psi--the pressure at which injector flow rates are determined.

So in a classic "back of a napkin" calculation, and if we assume a BSFC (Brake Specific Fuel Consumption) of 0.60 lbs/hr (typically the high end for supercharged engines), we get a raw value for maximum supported HP of 529.2 (317.5 / 0.60).

At the low end of BSFC for s/c engines (0.55 lbs/hr) it would be 577.3 HP.

Pretty damned close to the 500+ number "moose" posted...

BTW--RC Engineering has some great tech info and online calculators for dealing with injector selection.

I went through a bunch of this stuff with my '90 to '93 Miatas where altering the tune was not an option and everything was done by playing with injectors and fuel pressure...

SVTeeshirt

if you don't have one already you can get walbro from an ebay STORE for $109 shipped... the 255 ofc.

Sxynerd

Thanks for the help and the links... As usual, you're the best. I actually have 60# injectors that I bought, last year because i knew this would have sooner or later, lol.


I already have the 255. I'm going to find some in line areomotive pumps online. I'll post up what I find in a bit.

Mustang_NTriangle

let me know as I am interested in your outcome.

mills281e

Working with 42 lb injectors and a 255 feeding a twin-screws set-up, my latest round of mods took me from 400/400 to 440/484 and I was getting lean enuogh to require a KB Boost-A-Pump.

Sxynerd

What's your duty cycle on your 42's?

mills281e

I didn't ask Tim (MPH) what % they were at when he last tuned it.

cliffyk

At 440 HP and 43.5 psi fuel pressure you would be right at the calculated limit of 42# injectors--the real world is always less that that...