30 lb injectors enough?
Registered User
Joined: Sep 2002
Posts: 333
From: Palm Bay, Florida
Re: 30 lb injectors enough?
Originally Posted by Loadre
They'll work.....
...until they lock up from having their duty cycle maxed the hell out. Best case scenario you have to buy new injectors, which you should have done in the first place. Worst case, you'd better have some duct tape to patch up that hole in your oilpan.
An average track run for a car with 24 lb injectors will last about 13 seconds. That's 13 seconds of your duty cycle being maxed out.
I'm not trying to argue, but I know that I'd be pissed if I toasted a motor because some guy on a messageboard told me wrong.
To the original poster. Just go ahead and get some FMS 36#ers. They're not THAT much more than 30#s. Don't worry about a FPR either.
http://www.corral.net/forums/forumdi...s=&forumid=323
...until they lock up from having their duty cycle maxed the hell out. Best case scenario you have to buy new injectors, which you should have done in the first place. Worst case, you'd better have some duct tape to patch up that hole in your oilpan.
An average track run for a car with 24 lb injectors will last about 13 seconds. That's 13 seconds of your duty cycle being maxed out.
I'm not trying to argue, but I know that I'd be pissed if I toasted a motor because some guy on a messageboard told me wrong.
To the original poster. Just go ahead and get some FMS 36#ers. They're not THAT much more than 30#s. Don't worry about a FPR either.
http://www.corral.net/forums/forumdi...s=&forumid=323
He's asking if he needs to change injectors with what he has.
Yea, change the injectors... that's the way. And also you NEED a billet crank, billet pistons, billet rods... and a billet block... because it might come apart on him!!! And don't forget the billet driveshaft because you don't want to pogo stick the car from all that 400hp it might put out with his mods!
There is a BEST way to do everything, but for his application the stock injectors will work fine. No, his engine won't grenade.... if your injectors should stop working due to overheating from his 250laps around daytona speedway then they'll just stop spraying...there is a big difference between running lean and running no fuel.
I'm not telling him not to change them. I'm telling him the stock ones will work.
Everyone has thier own opinion.
Registered User
Joined: Sep 2002
Posts: 333
From: Palm Bay, Florida
Re: 30 lb injectors enough?
Originally Posted by Loadre
Don't listen to me. I've not toasted a motor because an injector stuck open and hydrolocked a cylinder or anything.
Duty cycle is implemented for a reason.
Duty cycle is implemented for a reason.
Also, if your injectors lock, they lock closed, not open. If they stick open, it's for a different reason than burning up the coils inside them. If they stop working, the fuel pressure will close them.
The duty cycle is implemented because how else can you control fuel spray with a constant flow rate and constant pressure without closing them?
I'm not going to argue about this because you have your way and I have mine. That's what makes hot-rodding fun...everyone has thier own way of doing things. But I wouldn't hesitate to run stock injectors on my N/A engine up to 425-450hp...in the end it would depend on what my data logger says. But most of the time they're fine.
-Dave C. '97 Z28
Registered User
Joined: Jul 2001
Posts: 1,887
From: Kingsport, TN
Re: 30 lb injectors enough?
Originally Posted by Dave C. '97 Z28
Ummm..hydrolocking comes from water getting in there, not too much fuel.
Also, if your injectors lock, they lock closed, not open. If they stick open, it's for a different reason than burning up the coils inside them. If they stop working, the fuel pressure will close them.
The duty cycle is implemented because how else can you control fuel spray with a constant flow rate and constant pressure without closing them?
I'm not going to argue about this because you have your way and I have mine. That's what makes hot-rodding fun...everyone has thier own way of doing things. But I wouldn't hesitate to run stock injectors on my N/A engine up to 425-450hp...in the end it would depend on what my data logger says. But most of the time they're fine.
-Dave C. '97 Z28
Also, if your injectors lock, they lock closed, not open. If they stick open, it's for a different reason than burning up the coils inside them. If they stop working, the fuel pressure will close them.
The duty cycle is implemented because how else can you control fuel spray with a constant flow rate and constant pressure without closing them?
I'm not going to argue about this because you have your way and I have mine. That's what makes hot-rodding fun...everyone has thier own way of doing things. But I wouldn't hesitate to run stock injectors on my N/A engine up to 425-450hp...in the end it would depend on what my data logger says. But most of the time they're fine.
-Dave C. '97 Z28
Registered User
Joined: Dec 1999
Posts: 1,697
From: Petersham, MA
Re: 30 lb injectors enough?
Well, you're both right. They will work, but definitely living on the edge. If you use the calculator I posted earlier and figure on a max duty cycle of 90%, you don't have to play guessing games.
Registered User
Joined: Oct 2001
Posts: 80
From: sea. wa. USA
Re: 30 lb injectors enough?
Here's my 2 cents.....I run 30's....100 percent duty cycle at WOT...Briefly...(your not at 100 percent the whole time you are at WOT)
455 RWHP, 447RWTQ....58 psi FP at idle, no fmu....
I'm programmed that way, "safe", is a relative term...No knock, showing 900's on my o2's....
Hoping to get my larger (proper sized) injector's soon, but this does work for now...
455 RWHP, 447RWTQ....58 psi FP at idle, no fmu....
I'm programmed that way, "safe", is a relative term...No knock, showing 900's on my o2's....
Hoping to get my larger (proper sized) injector's soon, but this does work for now...
Registered User
Joined: Apr 2001
Posts: 2,195
From: Springfield, IL
Re: 30 lb injectors enough?
Recommended #'s 0.45 for Normally Aspirated, 0.55 for Forced Induction.
You Entered:
Injector Flow Rate: 30 lb/hr @ 43.5 psi
New Fuel Pressure: 43.5
Number of Cylinders: 8
Brake Specific Fuel Consumption (BSFC)0.45
Result:
Duty Cyle Max HP @ Duty Cycle
80% 426.67 HP
85% 453.33 HP
90% 480 HP
95% 506.67 HP
100% 533.33
according to that, 30lb injectors at 43.5psi (which is wrong since SVO injectors are rated at ~39psi but it doesnt affect this equation in a negative way since LT1 psi should be 43.5 making the SVO 30's actually a ~32#)
30# injectors are plenty for the average heads and cam (and even above average) LT1 cars that you read about
so i dont see whay someone recomended 36#'s too him? according to that, its way overkill for what the fella has done! unless those are flywheel numbers, thats the only thing i wish online calculators would be more specific about rwhp or fwhp...
and you have to be registered to use any of the calculators on that site
You Entered:
Injector Flow Rate: 30 lb/hr @ 43.5 psi
New Fuel Pressure: 43.5
Number of Cylinders: 8
Brake Specific Fuel Consumption (BSFC)0.45
Result:
Duty Cyle Max HP @ Duty Cycle
80% 426.67 HP
85% 453.33 HP
90% 480 HP
95% 506.67 HP
100% 533.33
according to that, 30lb injectors at 43.5psi (which is wrong since SVO injectors are rated at ~39psi but it doesnt affect this equation in a negative way since LT1 psi should be 43.5 making the SVO 30's actually a ~32#)
30# injectors are plenty for the average heads and cam (and even above average) LT1 cars that you read about
so i dont see whay someone recomended 36#'s too him? according to that, its way overkill for what the fella has done! unless those are flywheel numbers, thats the only thing i wish online calculators would be more specific about rwhp or fwhp...
and you have to be registered to use any of the calculators on that site
Last edited by simple; Sep 14, 2004 at 08:05 PM.
Registered User
Joined: Jul 2001
Posts: 1,887
From: Kingsport, TN
Re: 30 lb injectors enough?
Originally Posted by simple
so i dont see whay someone recomended 36#'s too him? according to that, its way overkill for what the fella has done! unless those are flywheel numbers, thats the only thing i wish online calculators would be more specific about rwhp or fwhp...
30#s will work fine.
Registered User
Joined: Jun 2003
Posts: 3,557
From: Carol Stream, Il.
Re: 30 lb injectors enough?
CAMZ97, Heres a place that has some decent prices. www.gefracing.com, got that site from Simple. 
When I ordered mine they came in two days. They also sell matched injectors, if you wanna go that route to.
When I ordered mine they came in two days. They also sell matched injectors, if you wanna go that route to.
Registered User
Joined: Dec 1969
Posts: 482
From: Mukilteo, WA
Re: 30 lb injectors enough?
I'll guarantee you those are flywheel numbers. I'm right at 80% with 30's with 354 SAE RWHP which puts me a bit over 400HP at the crank.
One thing people forget to consider--injectors don't care about correction factors. On a cool day, I'm probably close to 420 actual HP. It's the actual HP that matters. If you live in Denver, sure you can be fine on stockers for ONE MILLION HP.... But that doesn't mean it'll work for me here. Since I'd like to stay this side of 90%, I will upgrade to 36's when I have my heads ported.
All you who think it's a waste can bid on my 30's when the time comes.
One thing people forget to consider--injectors don't care about correction factors. On a cool day, I'm probably close to 420 actual HP. It's the actual HP that matters. If you live in Denver, sure you can be fine on stockers for ONE MILLION HP.... But that doesn't mean it'll work for me here. Since I'd like to stay this side of 90%, I will upgrade to 36's when I have my heads ported.
All you who think it's a waste can bid on my 30's when the time comes.
Thread Starter
Registered User
Joined: Mar 2004
Posts: 123
From: Bronx,NY
Re: 30 lb injectors enough?
wow alot of info I feel like my brain is fried!
what about just going in the middle instead of 30 or 36.
I've seen 32lbs maybe thats the way to go btw the heads are now at olsens in rockland county NY its going to be done like the le2 setup from loyd
what about just going in the middle instead of 30 or 36.
I've seen 32lbs maybe thats the way to go btw the heads are now at olsens in rockland county NY its going to be done like the le2 setup from loyd
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