Just like the title says...

I was over @ grapeaperacing.com and was going over their fuel injector sizing page and realized that my injectors aren't big enough! Could someone confirm this please...

Keep in mind that 93 LT1 Injectors are 22#'s.

The below is with the fuel pressure @ 43.5 psi. All HP number are of course is @ the flywheel....

22 lbs. Max HP: 391 (100% Duty Cycle); 332 (85% Duty Cycle)

My engine's power is 400 HP, sowhat would be a good size injector to use? I was thinking of 36#, using the calculation, they can support 540 HP with an 85% DC. 640 HP maxxed @ 100% DC.

Anyone have any recommendations, links to buy, or any other info for me?

 

Checkout - http://www.rceng.com/technical.htm and play with the calcs there.

I dont like running injs over 80% DC. So with that in mind and the variables you suplied 22# injs only support 280fwhp.

For 400fwhp it would require a 31#er so I would just go with 36s.

Take note that this is with a bsfc of .50 and a 80% DC, those can be diffrent...

 

LT1's are closer to a lower 0.45 BSF from what I've heard. You'd obviously want to dyno the engine and check the pulsewidths to figure it out for your specific ride.

Even so, the "worksheet" link above says 24# are only good for ~350 fwhp @ 0.80 duty, and max out aroudn 430fwhp. We've seen a bit more than that on the stock injectors, so I'd wager its even as low as 0.445

22# @ 0.8 duty leaves you at about 320 fwhp... or ~270 to the wheels. Best way to find out though is to data log a WOT run and check your pulsewidths (and calculate duty cycles ). Anything above 90% duty cycle needs to be addressed with larger injectors or higher rail pressure.

 

400hp? ok yep... you'll need to ditch the stock ones. (although I've seen stock 24 pounders "get by" in an application like this)

31.5# reads as right for 0.8 duty, but you could easily look at 30 pounders for 0.85 duty and be safe. All depends on the brand of injectors you want to buy, and what sizes they have available. Get anything close to 31 (I'd go higher before lower) will be fine.

 

your not puttin out 400HP if youre trappin 103.8 unless you at some high elevation. 350ish HP = to about 105MPH in an F-Body

 

SVO 30# injectors should put you right where you want to be.

 

Your signature lists "DataMaster". That software will tell you the duty cycle on your injectors, and allow you to evaluate pulse widths, etc. Have you used it for that purpose?

 

i've got nothing but longtubes, a cutout, and a K&N air filter and i trap 105mph... which MAYBE on a good day is about 290hp (pushed 260rwhp stock)

so 350rwhp has gotta be faster than 105mph

 

30lb SVO's are rated at 38 or so PSI right? with the higher LT fuel pressure 43.5, wouldnt they actually work out to be about ~32lb/hr.?

Steve

 

Im still running my stock injectors and im trapping 110 na and 123 on the spray what injectors should I be running?

 

36# is what I'll go with.

I have datamaster, just waiting to get my cable....

Thanks guys... I gotta make a post on my low trap times to see what the problem might be....

 

LOL i wasnt talking about RWHP.i meant flywheel HP. 400HP should net you somewhere closer to 110MPH

 

I'm making 440+ HP and like 500 torque at the wheels on the juice with the stock 22lb injectors and my car is running richer than SH*T at all RPM's. Once I get my tranny fixed, it'll probably be closer to like 500RWHP. Believe me, you DONT need larger injectors

It never ceases to amaze me when I see guys around me who aren't making anywhere near the HP I make thinking they "HAVE TO UPGRADE" to like 30+lb injectors or something. (The last comment was NOT made about members on this forum )Trust me, keep the stockers. They'll be more than adequate. Just make sure they're working properly.

36# injectors? Holly marry mother of god. Thats takes the term "overkill" to a whole new level. Buddy, thats WWWWAAAAAYYYYYY to big for a car that only makes 400 flywheel HP. Crist, with injectory's that big, not only would you have to reprogram your computer but your car probably wouldn't even be able to run Maybe if you had like a supercharged 383 running 12lbs of boost than yeah, I could see 36# being an option but not for what you have now. If I run 22# on my car , you can do it with yours. Good Luck

 

wet or dry shot?

 

I have to agree with the above statement, to a point. I am still running my stock injectors and have never had any problems with running lean due to them. I ran for over 95,000 miles on my first setup, before I rebuilt my motor. The reason I had to rebuild the motor was due to the FMU diaphram going bad and causing a lean condition. BUT this was due to the diaphram not the injectors. So long story short are stock injectors good to a point yes, but if you are look at big HP# (I would say 450RWHP and above) the stockers are going to need replacing. Good Luck.