Fuel injector question
Racer
Joined: Dec 2005
Posts: 361
Likes: 0
From: Russia, Moscow
high-impedance injectors for L98
Originally Posted by lead foot 85 vet
What is the differrance between high and low impedence injectors and which do I want for my l98?............looking at around 65lb/hr
best for you SIEMENS/DEKA 60LB HIGH
http://cgi.ebay.com/ebaymotors/Sieme...spagenameZWD1V
i have it too
To me to like as it works
Pro
Joined: Jan 2004
Posts: 631
Likes: 3
From: Virginia Beach VA
Originally Posted by lead foot 85 vet
What is the differrance between high and low impedence injectors and which do I want for my l98?............looking at around 65lb/hr
What kind of HP are you running to require 65lb injectors? Unless your running high HP, I wouldn't recommend them since your ECM will likely have trouble sending such a short pulse width to the injectors at idle, and your idle will suck. If your anywhere around the 350-HP range, 30lb injectors will probably be better for you, and should stay under 80% duty cycle, which is ideal.
Pro
Joined: Jan 2004
Posts: 631
Likes: 3
From: Virginia Beach VA
Originally Posted by lead foot 85 vet
right now about 550 hp(guessing)....383...procharged@10lbs boost....running accell 36lbs injectors with a accell gen 6 ECM and the idle is ok but rich.........thanks
Thread Starter
Drifting
Joined: Dec 2001
Posts: 1,313
Likes: 1
From: providence ut
fuel pressure is about 38 psi....right now I have a fmu that only works half the time.....so no dyno and I stay out of the high boost....I don't know what the hp is...well built short block...9.5 to 1 compression superram,protopline heads flow 280 cfm,224 intake-236 exhaust duration@.50-.500 lift cam, 1.6 rollers,1 5/8 headers,2.5 dual exhaust with borlas..........looking for injectors that are alittle big for future grouth and that will idle well.
Pro
Joined: Jan 2004
Posts: 631
Likes: 3
From: Virginia Beach VA
Well, assuming 550-rwhp, conservatively, and 15% drive train loss, reverse the math and your somewhere in the neighborhood of 630-bhp. At 38-psi, 63-lb/660-cc injectors should work out perfect for you. You could go a little higher, but not much higher unless more HP is on the horizon.
Racer
Joined: Apr 2006
Posts: 300
Likes: 0
From: OKlahoma City OK 89 vert
Need to find out how much fuel pressure you have under boost with that FMU. I run ATI 8 psi blower w/FMU and my pressure goes up to 70lb. I also looked at taking off the FMU and running large injectors. But I was told the older stock ECU (84-91) can not control the injector. Ed Wright at FashChip.com told me to run 30lb with the FMU. Fix or replace your FMU and open it wide open.
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Thread Starter
Drifting
Joined: Dec 2001
Posts: 1,313
Likes: 1
From: providence ut
it's running about the same psi as yours depending how much boost I bleed off the fmu............the problem is some times the fmu doesn't work...it's about three years old.........I have a after market ecu so bigger injectors is not a problem......but burning down the engine is.....keep an eye on the fuel pressure as time goes on.....it's a procharger fmu with little time on it............I've had it apart two times.
you do know it's ajustable(fmu)...right?....you'll need to check your fuel/air under full boost to know what pressure to set..........when stock with 8 psi boost mine was sweet at 60 psi.
you do know it's ajustable(fmu)...right?....you'll need to check your fuel/air under full boost to know what pressure to set..........when stock with 8 psi boost mine was sweet at 60 psi.
Last edited by lead foot 85 vet; May 5, 2006 at 06:33 PM.
Safety Car
Joined: Apr 2001
Posts: 3,525
Likes: 2
From: Houston TX
Years ago I was running a very similar combo to yours (9 psi, 350 ci, massively ported SR, large heads, and a bit more cam). However, I was running a D1, and I was also at 570 RWHP. This combo used an FMU that would spike the 30lb/hr FMS to 78 psi.
If you step to 60lb/hr injectors and continue to run the FMU, I would expect nothing but problems. But if you eliminate the FMU, you may wish to go with somewhat larger injectors, just not sure if 60lb/hr is the answer.
Aaron
If you step to 60lb/hr injectors and continue to run the FMU, I would expect nothing but problems. But if you eliminate the FMU, you may wish to go with somewhat larger injectors, just not sure if 60lb/hr is the answer.
Aaron
Racer
Joined: Apr 2006
Posts: 300
Likes: 0
From: OKlahoma City OK 89 vert
Do you have an aftermarket ECU?
The chip should be tuned for your engine and blower. Yes, if your ECU can run 60lbs injectors then pull the FMU off.
Also, Please check with Ed or John at FastChip.com. That is all they do is GM dyno tuning and they drag (1/4) at the Tulsa, OK track. 
His # is 918-446-3019. Check him out!
The chip should be tuned for your engine and blower. Yes, if your ECU can run 60lbs injectors then pull the FMU off. Also, Please check with Ed or John at FastChip.com. That is all they do is GM dyno tuning and they drag (1/4) at the Tulsa, OK track. His # is 918-446-3019. Check him out!