What is the Max RWHP on stock injectors?

Like the title says. At what point do we upgrade to new injectors (same volume/better made) or larger injectors.

Thanks.

Injuneer will tell you his formula to figure this out, or you could search for it. I think its around 400hp fly wheel since driveline power loss doesnt mean anything to injectors. If you had to make a guess its close to 350rwhp.

-Dustin-

I did 405 SAE RWHP "NA" Stock rear. I was at 97% duty cycle at 6k rpms though...Depends on VE and other considerations (really it's your engine combos BSF that matters).....A stock compression 350LT1 might be maxed at 370-390 rwhp. FI max out pretty damn fast due to higher BSF numbers....

As was stated it will depend on your brake specific fuel consumption and what you consider a safe duty cycle.

FWHP x .07 = #/HR

I'm pretty sure that was the formula. Then the stockers are good to about 350 FWHP.

Eh, I think they are good for more than that. Most people are safe making aronud 350rwhp or 400 horse at the motor.

-Dustin-

Eh, I think they are good for more than that. Most people are safe making aronud 350rwhp or 400 horse at the motor.

-Dustin-

I think it depends on what kind of duty cycle you're comfortable running as well.

http://www.camaroz28.com/services/calcs/pwcomp.shtml

It's very hard to calculate VE, too.

damn, 405 rwhp on the stockers? I'm dynoing next week so we'll see, i have seen over 100% on mine before and expect 340-350 rwhp.

i was on the stockers at 427 rwhp and yes i was pushing the limit. a little to much but i never had a issue.

Ran the stock injectors for two years at 390rwhp.

i was on the stockers at 427 rwhp and yes i was pushing the limit. a little to much but i never had a issue.

You must have increased the fuel pressure sky high or the numbers are standard and not SAE. Seen 430 rwhp on 28's that had the fuel pressure set to 60 psi and personally made 465 on 30's but 427 rwhp on 24's is a new one for me.

Frankly I like the post that said 370-390 rwhp in a six speed being time to start thinking about larger injectors but I've seen a numbers of cars making 400 rwhp or just a little over/under with 24lb injectors. In the "old days" replacing the injecters was never a thought so that's all we used was stock.

My 97 SS was making in the mid 390 range and the injectors went static around 6000 rpm. When we went to 30 lb injectors it didn't make any more power. In hindsite we probably could have just bumped the fuel pressure up some and the net result would be the same.

Hindsite is usually close to perfect, it's looking ahead that gets a little blurry.

I put down close to 350rwhp and my injectors are maxxed out, but then again I still have the puny 14year old 19#'s from the factory. my car is a 93 so you guys (94-97) IIRC have some slightly larger injectors, and maybe a little more leeway to work with.

Well I'm just reading this and hoping for more folks to chime in with their
experience. I'll be installing ported heads and intake, and a set of SLP
shortys soon and will be in same situation. It seems to me that you would
be much better off with bigger injectors running on the low end of the duty
cycle than maxing out the stockers.

Quick question for you guys that run the stockers over 350RWHP, what fuel pressure do you run and do you still use the stock pump? can the stock pump really support the extra fuel pressure needed to feed 400 RWHP like some of you guys mentioned? I thought the fuel pump would only support so much pressure, and that's why most guys dont recommend in-line pumps with the stock unit.

You must have increased the fuel pressure sky high or the numbers are standard and not SAE. Seen 430 rwhp on 28's that had the fuel pressure set to 60 psi and personally made 465 on 30's but 427 rwhp on 24's is a new one for me.

Frankly I like the post that said 370-390 rwhp in a six speed being time to start thinking about larger injectors but I've seen a numbers of cars making 400 rwhp or just a little over/under with 24lb injectors. In the "old days" replacing the injecters was never a thought so that's all we used was stock.

My 97 SS was making in the mid 390 range and the injectors went static around 6000 rpm. When we went to 30 lb injectors it didn't make any more power. In hindsite we probably could have just bumped the fuel pressure up some and the net result would be the same.

Hindsite is usually close to perfect, it's looking ahead that gets a little blurry.
yeah i added a in-line pump to help. that was, maybe, 7 years ago

The 0.07 multiplier is a "rule of thumb" for getting the "ball park" size based on flywheel HP. It was derived by assuming a BSFC of 0.476 #/HR/HP and an 85% DC. A well-tuned engine, with efficient combustion chamber design can approach 0.45 BSFC and some people seem to get off on seeing how close to 100% DC they can push them. And all this assumes that the injectors are operating at the same fuel pressure they were flow rated at.

If you can do 0.44 on the BSFC and want to risk 100% DC, your up to 453 flywheel HP on a stock 24.9#/HR injector.

Remember also.... the dyno numbers you see are typically corrected to SAE or "standard" conditions. If you tested on a hot humid day, with a poor barometer, your engine did not actually produce the numbers on the dyno sheet. So you need to look at the UNCORRECTED dyno numbers when you are evaluating the injectors.

For the guy with the 93... your stock injectors are 22 #/HR, not 19.

Oh my bad, thought it was a 19# setup but I knew they weren't too far off from 94-97. Thanks for the correction and the update.

I tried the formula but it is only based on Engine Size, Max RPM, and at WOT. The formula doesn't have a calculation for HP consumed (Fly or Rear).

http://www.camaroz28.com/services/calcs/pwcomp.shtml

If using stock 24# injectors, consensus seems to indicate up to 370-390 RWHP with the fuel regulator adjusted to higher PSI. Anything higher may max the Duty Cycle and incur potential injector lock up.