What size injectors?

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scottp11

scottp11

The Seniorest Member....
I have a 93 Civic hatch with a JDM B16A (10.4:1 cr) swap. I ordered a turbo kit from Drag Turbo Kits with a T3/T4 turbo and 7lb wastegate spring. I was going to order the RC 310cc injectors with the kit, but everyone I talked to said that they were too small. I had to atleast get 440cc's. What size should I get. I have the Walbro fuel pump, and Eagle fuel rail with an adjustable FPR. Do I even need to get bigger injectors, or will my stock one's work fine? I plan to get Hondata S200 also, and have an OBD-1 P72 ecu right now.

I don't plan on turning up the boost, cuzz my engine is not built at all. Stock sleeves, pistons, rods, etc... Thanks for all the help and input!
 
i have 310 rc's and they're perfect for what you're building (boosted stock internal engine) i was going to put them on my integra gsr but didn't end up happening i also have a vortec fmu if you want them...
 
I have the FMU, it came with the kit... How much for the injectors though? Will my stock ones work for this kit? I have a B18B block that I plan on building later, for more boost, so I plan on getting bigger injectors anyway. But the block will not be ready for a while. Thanks for the help!
 
Also, what should my fuel pressure be set at for this setup? I used RC's fuel injector formula, with my fuel pressure set a 38 (what i'm at now N/A..) and it says I need 630cc injectors to make 280 crank hp? is that right?

Here's the site: Fuel Injector Technical Information - RC Engineering

Thanks again for the help!
 
630CC INJECTORS?!?!? you're gunna get like 4mpg!!! that can't be right...i'm no engineer for RC but 280 crank hp is not THAT high of a number to need those huge injectors...i heard that my 310's in a b18c @ 6lbs = 250ish hp+ so idk exactly what you're lookin at...hope this was informative at all...
 
Enter the info for yourself, that's what it says.... I knew that can't be right.... Can someone give me a straight answer? What size injectors do I need for this current setup? Thanks again for all the help!!!
 
if you're running the fmu, use your stock injectors.
if you're going to do it right, throw out the fmu, get some 440 or 450cc injectors, and a tuning program such as crome
 
Thanks man. Yeah, alot of people told me to get rid of that FMU also. 1994turbodelsol says he'll sell me some DSM 450's for $110 bucks, and I got a Walbro 255lph fuel pump on its way, so... That should be good right? Like I said before, I got a Golden Eagle fuel rail and an adjustable FPR. Should I get a new/aftermarket fuel filter also? Will it make any difference?
 
that should be plenty of fuel, and jeff is giving you a good deal on those injectors.
 
It must lick balls trying to mod a civic in California.
 
Yeah, I live in El Paso, Texas. We have emissions testing, but nothing like when I had to SMOG in California. Shit, I just pay a guy an extra $20 bucks to give me an inspection sticker and run a test on another vehicle with my information on the results. Been doing it for years. Too easy. Cops here don't pull people over for having loud exhausts or blow off valves, and shit like that. They're too busy looking for illegal aliens from Juarez, Mexico....
 
There's quite a bit of misinformation here. The amount of fuel you need is dependent only on how much power you want to make, what AFR you want to run, and what IDC you want to be at max. And, for the record, running 630cc injectors does not = crap gas mileage unless you're constantly boosting or something. If you can get your fuel trims in line and adjust global correctly, the car will run exactly the same as it would with stock injectors. As another way of putting it, if you're only using 50cc/min of fuel while cruising, it doesn't matter if you have 50cc injectors or 1000cc injectors, you're still going to be using 50 cc/min of fuel.

As far as how big you need, that depends on your airflow. As far as I can remember, Honda heads are generally pretty good when it comes to VE. Thus, you can make the estimation of 9-10 hp per lb/min of airflow. Thus, to get 220 whp you should be looking to flow about 24-25 lbs/min airflow, which, from my experience is about the max of the DSM T25.

For fuel then, you can estimate how much you need based on the airflow number you just got. Assume you want to run 11.5:1 AFR, then for 25 lbs/min airflow you will need 2.174 lbs/min of fuel. With a simple conversion, assuming .76 specific gravity for 93 octane fuel, you need a total of just under 1300cc/min of fuel. Since you don't want to run 100% IDC all the time, lets say you want 80% IDC max, meaning you need ~1600cc/min of fuel. Divided by 4 for 4 injectors gives you 400 cc/injector.

Cliffs notes: Do some easy math and decide what you need based on your goals. But, if it's to max the turbo you have and net roughly 220 whp, get the 400cc+ injectors.
 
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