ismael-robert

Hey everyone are DSM 450cc injector sufficient to push 9psi with the JRSC? If not are there some other car's injectors I can get for cheap I really don't want to spend a few hundred bucks for RCs. I see all these threads for 9psi and 12psi, but is it not possible to go 10 or 11psi with a JRSC?
Has anyone run an 11:1 CR with the JRSC such as a JDM Type S motor? I know I'll probably need pistons in future and not sure if I want to stay stock or push it up one notch...I know this is not what superchargers like but I like low end acceleration.

ion_four

I'm running 9psi with 440cc injectors and am pig rich, so yes you'll be fine. However, you will be getting injectors with 100k+ miles on them and should have them flow-tested and restored. Three could be rich and one could be lean, so your AFR will look fine, but your engine will pop.

I wouldn't concern myself with keeping high compression with a supercharger. The supercharger raises the effective compression ratio (I believe 9psi + 10:1 compression =~14.x:1.) Low end acceleration is awesome with the USDM engine and the JRSC. I think 9psi should be fine with 11:1 and 92-93 Octane, but google octane and effective compression ratio and see what you find. If you live in some place with only 91...I'd maybe stick to 6psi to be safe.

ismael-robert

Thanks for info...so have you had your car tuned and still running rich? Or are you perhaps running rich cuz u have no tune? In other words do you know for sure your injectors aren't being overloaded?

ion_four

The car was professionally tuned before I bought it (Hondata Stage 3b can only be tuned by a Hondata dealer.) I don't know what "overloaded" is. The safe limit of injector duty cycle is 80-90%, depending on who you ask. I'm sure mine aren't at that point (300 crank hp is an approximate limit for 440-450cc/min injectors.)

I used to have a ~300+ (never dynoed) crank HP car and upgraded the 440cc/min injectors to ~560cc/min injectors because I was at approaching 100% duty cycle.

willybv

You duty cycle will vary depending on your altitude, the safety of you tune (read: duty cycle) and other factors, such as the octane available to you in your local gas station. The widely agreed upon MAXIMUM duty cycle for a reliable injector is 80%. An injector running over this duty cycle, especially a used OEM injector may become unreliable. The previous poster stated he was safe on his setup with a smaller injector, and that's very feasible. I'm running a safely rich tune, and very good tune on my 9psi Jackson/H22 with RC 550 injectors, and the duty cycle is just over 80%. With brand new performance injectors, I'm not too worried about it, but I wish that I had stepped up to 600s. You can go to the RC injector website (RC Fuel Injection), and they have a table that will calculate a ballpark estimate of what you need, so that you can round up from there. A good dyno tuner should be able to keep you idle ok with a large injector. The table assumes a 43 psi fuel line pressure, a bsfc of .55 to .60 for a blown motor, and allows you to select duty cycle, desired horsepower, etc. The bottom line is that bigger is better in this scenario, with the limiting factor being a larger injectors ability to precisely meter fuel at idle, when demands are low. Using a peak and hold injector, this is not too much of a problem with good tuning and a reasonable projection of what you are going to get out of the motor. Good luck!

ismael-robert

Wow 80% on 550 well I think that answers my question. I'm in San Antonio so no extreme altitude here and we have 93 octane.