I was wondering what would be best for my project. I'm sure the info is out there, and I've spent days looking, but I haven't found a steady answer yet. I have a 383 stroker with 10.4 to 1 compression and I need to know what size fuel injectors to buy. Some people say that I need 40# injectors to make sure that the engine doesn't starve and some people say that I need to go way lower because it will blow up the engine. I know that there is a formula out there, but I haven't been able to find it (plus i suck at math). If anyone could help it would be greatfully appreciated.

 

whats the expected HP output? i dunno the formula off hand but i do have it sumwhere. i can tell u right now that if ur making up to 500hp that the 36lb accel injectors will be good.
im putting my 383 together and i'll have around 500hp so i already got the ford SVO 30lb's.

the injector size is important but the tuning and changing the fuel pressure is just as important. u can run a stock 21lb 350TPI injector at stock psi 38 and it'll be 21lb but u can increase that psi to 50 with the same 21lb injector and it will act like a 24lb. get it? u dont wanna go lower than 37psi bc then the spray from the injector gets alil funky.
accel 24lb are good for 350-450hp
accel 36lb are good for up 2 500-550hp
ford SVO 30lb are the same as above
accel 40lb are good for i think 600hp or so

 

Thanks, that answers my question completely, It was dyno'd at 425hp where I bought it from and I don't plan on going over 500hp with it.

 

I am running my 395 cu.in. stroker with 24#/hr Ford Racing injectors with the AFPR set at 52psi most of the time. I know that I am maxed out on these injectors, therefore, this Spring I will be installing 30#/hr injectors.

I would think that a well running 383 could use the same 30#/hr injectors and get plenty of fuel via an AFPR.

 

I currently have 30 lbs accel injectors on my ride, works perfect. Just make sure you get it tuned well. The only reason you would need bigger with a 383 if its not n/a or you want to throw a little shot of nitrous.

 

And, of course, you will need to have a custom Eprom chip burned for the injector flow rate.

 

Yep. Can't forget about the chip tuning.
There are formulas out there for figuring out what size you need. If you do a search on these forums, the websites will be revealed.

I'm running 36# on my 383 with a "supposed" 541hp. No true dyno numbers yet. I'm still tuning the fuel.

 

The equation is:

engine Hp = (inj flow rate)(# of inj)(DC) / BSFC

The flow rate is in lbs/hr,,, DC is the duty cycle (normally set at .80),,,
BSFC (if I have this right) is the basic specific fuel constant or comsumption factor. For our 3rd gen TPI cars, the value 0.5 is used.

For me, I would have (the 24s flow about 27 at 52psi):

engine Hp = (27 #/hr) * 8 * 100% / 0.5
engine Hp = 432 Hp or about 375 Hp at the drive wheels (that is very close)

Since I know from my scanner that I am maxed out on the injectors, I use 100% for the duty cycle.

To determine the required flow rate;

injector flow rate = (engine Hp) * BSFC / (8 * DC)

 

If you run the 24# you can get away with not tuning. It will run just not at its best. use a 350 chip.

svo 24 + adj fpr = 22-27 lb