LS1 fuel system: How much can it support?

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Feb 24, 2005 | 10:12 AM

Juiced346

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From: Conway, AR

LS1 fuel system: How much can it support?

Anyone have a clue how much the stock fuel system (w/ walbro 255, 30lb injectors) support? I have no clue the capacity of the rails nor the lines. I might have to get a aeromotive system on there if need be.

Feb 24, 2005 | 11:16 AM

MIGHTYMOUSE

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From: Virginia

without the wet shot you'd be limited by the injectors at maybe 500rw (non FI)

Feb 26, 2005 | 08:09 AM

onfire

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From: Virginia

I wouldn't even think about rails until +600rwhp. With a wet kit you will exceed the pump capability before the rail limit.

Mar 6, 2005 | 04:28 AM

MakkMarci

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??? I cant understand the injectors max hp

Hi!

I try to check the problem to here:

http://www.rceng.com/technical.htm

so, I try to calc the injector size for 500 FWHP.
fuel rail pressure is about 50PSI (checked in 1998 GM service manual)
I filled the fuel injector worksheet:

Actual Desired HP : 500 FWHP
Num of Inj: 8
BSFC = 0.5 (no turbo/charger)
MIDC = 0.8
System fuel pressure/fuel rail = 50PSI (48-55PSI)
inj. req 36.44

so max bhp with #30 injectors : ~ 400 FWHP (~350 RWHP) (calculated with this calculator)

Is this a correct calculation? but lots of ppl say, stock 26/28 injs.are enought for 500RWHP (about 580-620 FWHP). I don't understand this...

thanks for help

Mar 6, 2005 | 09:56 AM

Old Geezer

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From: GA, USA

Nope!!

but lots of ppl say, stock 26/28 injs.are enought for 500RWHP (about 580-620 FWHP). I don't understand this...

You are correct. The 28's will not support that kind of HP.
I'd like to see their logic behind this statement.

I maintained alot of stock injectors for the now defunct, ASA stock car racing program. We ran the FP at 60psi, and found they would support approx 480 FWHP. [LS-1 spec engines.]

Mar 8, 2005 | 01:59 PM

SSpeedracer

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They might be runnig the 26/28 lb at 100% duty cycle instead of 80%. Still a stretch however. The problem with high impedance injectors is that they are more difficult to control at the extremes of their flow range. Factor in voltage drops and it is even worse. In other words there is very little flow difference between 90 and 100% duty cycle. Common practice is to limit at 80% max flow rate to control flow and reduce heat.