pontiacpete

hi guys im trying to match up everything before i burn a new eprom my motor should have 450hp at the flywheel at the moment ive got 22lbs injectors are they sufficient to feed the motor i also have a adjustable fuel pressure regulator can i get away from this combo also thinking of nos in the near future

Dragroc

Maybe this'll help ya out...got it off www.rceng.com I think this is the site...

rockind78

Small problem.....injectors aren't normally run at 100% duty cycle. They are normally run at around 80%. Nice table though!! Here...this should help:

http://www.smokemup.com/auto_math/fuel_injector.php

And now that I have looked at it, I like this one even better:

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

Thanks for the site '89Z28!!

Jstcrzyengh

iTrader: (2)

I did a calculation on that site using the following:

24lb injectors (LT1's)
est. hp. 400
85% duty cycle
bsfc .45

Says I need a 28.13 pound injector...

This # seems a little off as LT1 guys run these injectors to 400 hp with little to no problems with their stock injectors. Am I missing something?

Grim Reaper

That's only if you obtain a BSFC of .45, which indicates a very efficient engine. Most people esitmate a BSFC of .50. Also, for any given engine, as the rpms increase past 3,000 rpm, the BSFC increases. You should use the BSFC of your engine at your max rpm before you shift.

doc

What Glen said.

Our L98 engines are about .50 or higher for BSFC. The LS1 engines might be 0.45, but not our L98s. Also, because they are batch fire, we are limited to 10msec of pulse width on the injectors at 6000rpm, that would be 100% duty cycle. If you are going to be making 450HP, you will most likely be spinning the motor up to at least 6000rpm.

28#/hr flow rate is probably the minimum flow for 450 flywheel HP. IMHO, of course.

John Millican

iTrader: (1)

They don't run at a set "duty cycle", the DC changes as more demand is places on the engine and rpm's increase.

The only way to really tell if you're hitting high percent marks is with a scan tool.

I had a buddy with a stock IROC and he wanted to upgrade his injectors to 'make more power'. After i scanned his car and showed him he was only using 60% DC on his injectors i convinced him not to waste the money.

Greg90iroc

I have seen as high as 10.7 ms on my injectors at 3700 ft altitude. what gives? I know i am not making that kind of power since my fule pressure is at 48 psig the injectors are efectivly 23.5's That is enough fuel for 400 hp.

doc

At what eng RPM was the 10.7msec PW?
If it occurred at 5000rpm, then you were at 89% duty cycle.
At altitude the air is less dense, so the ECM should demand a shorter PW at compared to sea level.

I have talk to a few dragracers who run EFI in a serious manner. They basically say that you can run injectors at 100% DC for a short duration like a run down the dragstrip.

11SEC91Z

iTrader: (4)

Well fellas thought id post in here.. put my .2 cents in..By no means am i getting into injector debate....Not saying it always works or is the best thing.But i have 22 lb injectors in my car and run low 11s.. so it is possible..i run 54-55 psi FP..I may have gotten extremly lucky on my combo..But they will support that much HP atleast in certain situations..Again just FYI