Fuel Injectors - So many options, Need help!!

We may earn a small commission from affiliate links and paid advertisements. Terms

rfrumusa01

Bean Cakes
My 97 Civic Turbo is probably in the 300hp range @16psi (fully built), with OBD 1 Conversion. Right now, I am using DSM 450cc injectors on the stock rail and FPR, but a walbro 255lph pump, wired with the 10ohm resistors.

Is this setup correct? or can I unlock more power with larger injectors/higher fuel pressure? I was looking at injectors, if I were to upgrade, what size and saturated or peak and hold? There are so many out there, I am totally confused. Hondata claims my size injector is not good at all considering the power range.

TIA..
 
The Hondata folks probably meant that it sounds like you may be operating at the upper limits of your injectors. If you are going to change injectors anyway, go with a 750 to 1000 setup. They cost about the same and give you lots of capacity for future boost increases if you decide to turn up the pressure. Tuned properly, they idle and run as well as the smaller capacity injectors. As usual, make sure your timing and afr is dialed in, if you want it to last.
 
Go with the size you need, not some large arbitrary number. If you have lots of unused capacity on your injectors, you lose a lot of resolution when you tune.
 
Sorry to hear that you have resolution problems. It hasn't been an issue for me. Don't know what is different about what we are doing?
 
ehh, maybe for muscle cars that may be accurate....

How to size fuel injectors.
[FONT=verdana,geneva]In order to properly determine what size fuel injector you should be running for your application you need to apply the following equation:

(Power x BSFC) x (1 + Safety Margin) / (# of injectors)=pounds/hour

BSFC for forced induction cars is between .60 to .70 using gasoline.

Power is maximum horsepower level you want to run.

Safety Margin
is to be set between 15-20%.

To illustrate this:

Power=500 hp
BSFC=.70
Safety Margin=0.2[/FONT]
 
Well that helps... not sure what BSFC or margin is, but using the numbers you gave me and my estimated 300hp, looks like after converting lb/hr to cc, I need roughly a 660cc injector.

As for the fuel pressure, whould I need to alter the fuel pressure at all? When I install the new injectors, would it be beneficial to change my FPR and re-tune the ECU? I'm a little sketchy on messing with the fuel pressure. Mainly, I would like to know if new injectors requires a re-tune. I know I will need to re-tune if I change the fuel pressure.
 
im at 233whp and using 450cc's im doin my upgrade within a month and ill b around 350-380 and im using 750cc's u should b good with the 660 u said u need. are u tuing ur car or taking it to a shop to have it done? i would say after any upgrade it needs to be retuned. depending on what turbo u have im surprised that u dont have more whp with being fully built. but if ur guessing then u dont know for sure. how come u havent had it dyno?
 
I'm just guessing with lower numbers so I'm not dissapointed when I get it dyno tuned this spring... but the car has already been street tuned using crome, seems it was done very well. I do see most people with my setup with 750's, i will stick with around 660cc and go from there. Do I need saturated or peak and hold??
 
Back
Top