I'm goint to install a 9 psi ATi kit on my superrammed 383 how big injectors do you think I will need. Today I'm running a mod. PROM and stock 22 lbs injectors 50 psi FP. I was thinking of getting SVO 24's........

 

HP X .55 / # of cylinders. Accel

500 X .55= 275

275 / 8=34.38 lb per hr injectors

Try 36/42's. IMHO

 

I cant affort any DFI equpment at the time. So my plans is go with #24 SVO and say about 45 psi FP and then use ATI FMU that will raise the FP when ist under boost. The question is would #24 be enough under boost.......Dont know how high the FP will be with the procharger......

 

If you looked at your options you would find out you can afford computer controlled fuel managment under boost. Just go to the junk yard and ask for a 1227749 ecm (+- $50). Then use your V8 memcal and the syclone/typhoon .bin file. Then you just need to buy a 2 bar map sensor and your larger 36~42lbs/hr injectors. Thats what I did and after burning about 50 chips my car is very drivable now and you would never know it doesn't have the original computer in it.

 

That is what I mean-you can use high impedance injectors with the STOCK computer-they are available up to 55 lb. per hr. you need more fuel-period-don't learn the hard way like I did-replacing injectors is easier than leaned out pistons-(JE pistons burn too)

 

If you're really making 500 hp at the crank (400rwhp), this would be cutting it close, too close. You're leaving out duty cycle, which if at all possible you should shoot for 75-80%, or 46# injectors.

On a blown engine BSFC can also go pretty high, over 60%. Add to that, he should be making more hp more then that if he sees 9psi. The 383 should be pushing close to 400 hp, 9-10psig non intercooled should put him at around 600hp. With a good intercooler it could be as much as 700hp.

A 'safe' setup assuming that he's making between 500 and 700 hp would be somewhere between 46-70# injectors. That's not to say that he can't get away with 36's with 500hp (my brother is running 36's in a car going 11.5@120, but he's seeing 102% duty cycles), but if you're starting from scratch I wouldn't plan your setup to run at the ragged edge.

Also, you can get enough fuel with a relatively wimpy pump if you keep your pressure down, and it seems like pump requirements go up exponentially from there. I know that you can get away with a single 190L/hour pump at 500 hp if you're running big enough injectors to do it at 35psi, but you'll run out of fuel with a 255L/hour pump if you need to jack the FP to 55# to get enough fuel on the same engine

 

Talking to the former owner of the ATI kit, He had 90 psi FP under boost.

So SVO #24 at 90 psi #36......

I will start with get the engine running......and theh see if I could get $$$ for PROM burning........

Until that I'll have to stick with #24 SVO's.......

I'll let you know how it goes!