lowglider

DOES ANYONE KNOW FOR SURE WHAT THE STOCK INJECTOR SIZE IS IN
MY 1991 L98 ENGINE, 19LB OR 22LB, AND WOULD A 24LB INJECTOR UPGRADE MAKE ME RUN TO RICH? I HAVE K&N FILTER,AIRFOIL,HYPERTECH
CHIP,AND STRAIGHT DUALS WITH DYNOMAX ULTRA FLOW MUFFLERS.

ToniH

I am sorry, I can't remember it for sure. But anyway: you need about 19.1 lbs/hr to feed a 250 hp engine. So, 19-22 lbs should be enough for your engine even if you add some more mods.

Formula to calculate the correct injector size is:
BHP x BSFC / no of injectors x duty cycle = reguired injector size

BSFC is about 0.45-0.5 and duty cycle is 0.8

Many have gone to 24 lbs and are reporting no problems but they _will_ run rich at idle and WOT. Those who have scanners have verified this.

Remember also that GM and ACCELL injectors are rated at 43.5 PSI and Ford/SVO's at 39.5 PSI of fuel pressure. So running FORD injectors at stock Vette fuel pressure will make them flow even more than they are rated for and stock computer can't adjust such a big difference, this is causing rich conditions (if 24's are used i mean).

I would go with 19lbs Ford injectors or 21-22lbs Accells if I were you. Actually I did order the 19lbs Fords for myself for similar car after doing the math. They will flow 20.9 lbs/hr with stock Vette fuel pressure and if I adjust the pressue up to lets say 47 psi they will flow 22.6 lbs/hr so enough room for adjustment for my purposes. :D

Take a look at these pages for more info:
http://www.holley.com/HiOctn/TechSer...l/Artcl07.html
http://www.msdignition.com/fuel_1.htm

and for calculators:
http://members.tccoa.com/jmiller/finject1.htm
http://www.smokemup.com/utilities/ca...l_injector.cfm

Greets,

Toni


[Modified by ToniH, 7:11 PM 5/12/2002]

LPDesRoche

The stock injectors in a 91 L98 are 22#'s. They can handle alot HP than people give them credit for. You just need to have the prom adjusted to recognize the need for more fuel.

You do not need to upgrade to a 24# unless you were just trying to replace the stockers because they are bad....

vette_tweak

Yes, they flow 22# at 43PSI of fuel pressure. Increase the fuel pressure and you can easily make them flow 24-26#s. This actually helps with fuel atomization too which translates into slightly higher HP. You can run in the high 11's with the stock 22# injectors. :cheers:

cshuman

LOWGLIDER NOT TO CHANGE THE SUBJECT BUT I NOTICED YOU HAVE TRUE DUALS WITH ULTRA FLOW MUFFLERS. I JUST INSTALLED DUALS ON MINE WITH STOCK MUFFLERS. I WANT TO CHANGE TO A DIFFERENT MUFFLER BUT I DON'T WANT IT TO BE TO LOUD OR HAVE ANY RESONANCE. HOW DO YOURS SOUND?
THANKS

lowglider

HI, I HAVE STAINLESS STEEL DYNOMAX ULTRA FLOWS AND THEY SOUND
REALLY GOOD ABOVE 2000 RPMS , BUT ARE VERY IRRITATING BETWEEN
1500 AND 200O RPM BECAUSE OF LOUDNESS AND RESONANCE. IF YOU
ENJOY QUIET SLOWER CRUISING I WOULD STAY WITH STOCK MUFFLERS.
THIER IS A DYNOMAX STOCK SOUNDING MUFFLER THAT CLAIMS 30% MORE
FLOW BECAUSE BOTH OUTLETS ON MUFFLER ARE OPERATIONAL AS OPPOSED TO OEM WHERE ONLY ONE OUTLET IS OPERATIONAL. THIS MIGHT BE A GOOD CHOICE TO GO WITH.

ToniH

Huh, lots of shouting here (capitals).

But i second that comment about Ultra Flow SS's. They are very loud when driving about 45-55 mph (A4&3.07) but then it quiets down to very nice sound level. I plan to install some sort of sound insulation stuff under my rear carpet to make it a bit quieter.

Greets,

Toni