331 question

His injectors are NOT at all to big for a n/a 331. I run 30's on my n/a 347 and they're 100% MAXED out as shown by the duty cycle on my PMS.

How do you know he's running rich?
 
His injectors are NOT at all to big for a n/a 331. I run 30's on my n/a 347 and they're 100% MAXED out as shown by the duty cycle on my PMS.

How do you know he's running rich?

I may have some 36's for you if you want :D Anyway, I think 24's "can" work in a 331 depending on "supporting cast" and likewise with 30's
RC
 
30# injectors are not at all too big for a 331. in fact, they may be too small, depending on the heads, cam, and intake. putting down 375 horses at the tires is not unheard of for a 331. at that level, i bet 36 or 42# injectors would be better
 
hes got a cobra intake, 80mm mass air, short headers, gt40 iron heads, cold air intake, a receint tune up, msd cap, rotor and coil, ford racing wires, 70mm tbody and spacer. his tail pipes are black and he uses an inordinate amount of gas. he says it is a wolverine b cam, the guy he got it from was supposedly using a 200 shot of nitrous then he took it off when my buddy got it. It also seems to miss when it gets hot.
 
I think he needs to tune his car. 30 pound injectors will most likely be OK with that combo, though I would steup up to 36 pound injectors.

One thing you both need to realize is that the size of the injector has NOTHING to do with how lean or rich the car runs, its all in what the computer tells the injector to do.

Adam
 
It all depends on the top-end pieces.

An N/A 347 could do fine with stock top-end pieces with a 19 lb. injectors and a 5,500 RPM shiftpoint.

Then, you could have issues with 42 lb injectors shifting at 7,500 RPM with a nice top-end.

The best one I have found to use is from FTI's website:

How to Calculate the Correct Injector Size:

IHP = Ideal Horsepower
NIJ = Number of Injectors Used
IDC = Injector Duty Cycle
BSFC = Brake Specific Fuel Consumption

Example:

300 HP / 8 cylinders = 37.5
37.5 X .50 BSFC = 18.75
18.75 / .80 Duty Cycle = 23.43 lb/hr injector (24 lb/hr is the closest).

This will vary per BSFC you want to run and injector duty cycle preferred.