injector question???

[g2ic02]

to start off i have a redtop sr20det with full exhaust and fmic and i searched...after i had searched for a while i found a post with a formula that takes horsepower at the fly and converts it to how large of injectors you need at a certain duty cycle.....with that in mind i found at 80% duty cycle the stock 370cc injectors are good to about 320hp @ fly....to me this doesn't sound right(i will try to find the thread)....so on to my actual question....i am looking for injectors to go along with a Z maf and my t28. I plan on making roughly 250-270hp. Which injectors should i get; the s15 4??cc, or go with 550cc. I plan on rom tuning. Thanks in advanced..

[g2ic02]

To figure out what size injectors you need, use the following calc..

Injector Size = Expected BHP (brake horsepower (at flywheel)) x BSFC (brake specific fuel consumption)/Number of injectors x duty cycle

A good BSFC for a performance NA street engine is .45-.50 to be on the safe side, lets use .50.

Lets use 90% duty cycle..

So if you expect 220 bhp.. 220 x .50 /4x.9 = 30.5 lb/hr injectors.. round up. so 31 lb/hr

to find cc/min multiply 31 x 10.5 = 325.5 cc.. in general, if you have two injectors sizes to choose from one being 310, and one being 360cc.. always round up to the next closest size.

this is what it said in the thread posted by sykikchimp

[Flybert]

If you are going for 250, you can stick with stock injectors but if you are going to be going with 270 or higher, I'd suggest upgrading to S15 480cc or a 550cc. Personally, I'd just go for the 550cc because you will want to upgrade in the future.

[bchumley]

this is interesting to hear, cause I've been having a real hard time determining which injectors to run. I expect about 500 bhp, and was thinking either 740cc or 850cc injectors. this equation points me towards slightly smaller ones. hmm. any thoughts?

[SPEC_R_SILVIA]

i have the nismo 740cc's in car and there good for 450rwhp on pump gas but thats pushin it 95% Duty i guess it cames down to how much power you want

[trixxxr4_kids]

be lazy and average out 75-85 HP per 100CC of your injectors
so lets say you have stock 370s average that the max is at 300-340
its like guesstimating (WARNING!not to be taken entirely serious)