So if I read this right, you have several thousand dollars worth of parts in that setup. Just the AFR heads have to be around $2000. So what's the big deal about getting a set of 30# injectors? Why are you willing to risk damage to that expensive motor to save a couple hundred dollars?

I paid $219 for 30# Ford Motorsports injectors. On an LT1, the injectors come out closer to 32-33#, because Ford rates them at 38 psi (vs. the 43.5 psi on an LT1).

 

I didn't see anyone answer the amount of horse power a 24# injector was worth. Or did I not read the other answers correctly. well here goes.

The formula is Hp= lb/hr flow rate x 8 injectors x .8 (80% efficiency) divided by 0.5 (BSFC) efficiency of the engine.

So 24 x 8 x.8 / 0.5 yields 307 hp.

So maybe the answer to your question is 307 HP.

If you rearrange the formula for injector size you get:

inj flow rate = engine Hp x 0.5 / 8 x 0.8 or

Inj F R = eng Hp x 0.5 / 6.4

You have to know what your expected hp is going to be.

 

Actually,i bought the car built,the car is equipped with LT1 Edit programmability,previous owner seems to be a knowledgeable tuner,he told me the 02 voltage always maintains between 750-800 volts which is not lean,even on spray,so thats why i brought the subject up,the car runs good & i dont like to change something that is working good,the combo has a good 3k on it & so far nothing has been damage,i just always thought the injectors seem to be on the small side for the combo but im sure they are working at a high duty cycle were as a bigger injector would not have to be pushed as hard

 

Those online "how to size injector" formulas tend to be extremely conservative. A well tuned NA performance motor should produce BSFC's well below 0.50 #/HR/HP. 0.45 isn't unusual. Also, consider that GM uses 24.9 #/HR in the stock programming for the stock injectors. Just making those two minor tweeks moves the limit up to 355HP. Push the duty cycle to 85%, and 375HP is the number. So.... 307HP isn't quite correct. There are too many people making over 400HP on stock injectors, at stock pressure. I personally wouldn't push an injector to 90-100% duty cycle, because its likely you are risking HP loss. My recommendation would be to go to a 30# injector over 375 flywheelHP. Go to a 36# injector over 475 flywheel HP. 42# over 575 flywheel.

And those are the limits for stock fuel pressure (43.5psi). Go to 58psi, and the numbers become:

24# max: 440HP
30# max: 550HP
36# max: 660HP

Just to clarify one of the comments made in a post above, the Bosch/FMS/SVO injectors are flow rated at 2.7 bar (39.15psi). Running them at 43.5psi does net you about a 5% gain in flow. A 30# injector will flow about 31.6# at 43.5psi.

As far as saying you can run a 175-shot on the 24's.... it means nothing if it is a wet nitrous system, since you aren't using the injectors for the extra fuel. Do you run a wet system, or dry?

As far as the comments about the tuner knowing what he was doing and saying:
First, we'll assume he said "750-800 milliVolts", not "750-800 volts". Second, stock narrow band sensors are simply not accurate at the kinds of A/F ratios you need for peak torque and power, and a knowledgable tuner won't rely on them. But... as a general guideline, an NA setup properly tuned is probably going to be ROUGHLY in the range of 850-900mV, and an engine running spray is going to be wayyyy richer than that to stay in one piece.... well over 900mV's. Run a heavy shot of juice at 750mV on a stock narrow band sensor, and you will most likely be picking up the pieces.

 

i was more or less going to say the same thing. The 02s are a guide at best. I had mine dialed in NA at ~.850, put it on the dyno and it was WAY lean. Made peak power well above 1000 milivolts.