I need help with selecting my injector size. I just got my engine re-build and in doing so I also made a few ungrades to my set-up I currently have a intake, 99 spec turbos, intercooler, down pipe, mid pipe and exhaust. I am managing this with a power fc. I had the car tuned after the re-build and we could only boost to 7 psi due to maxing out the injectors (which is a mistery to me since the injectors work for the stock boost of 10psi). Originally I was going to put my spare 850cc in to the primary, but I've dicided to upgrade both the primary and secondary; however I don't know what size to upgrade to. My goal is to push about 320ish rwhp so I don't need anything crazy.

With my set-up does anyone have any recommendations? or what are youusing withyour set-up?

Thanks for any 2 cents

 

The simplest and cleanest is keeping your factory 550cc primaries and adding 1680cc secondaries with resistors. You'll retain an excellent idle and have more than enough fuel for the life of your setup. Good luck!

 

You can also have your 850's bored out to 1300. That way you can keep all the stock plumbing (fuel rail, fuel pressure regulator)

 

Or you can keep the stock injectors all around, replace the FPR with an adjustable one, and run a higher base pressure. The spray pattern is also improved by running a higher base pressure.

Add a fuel pump rewire to whatever you do, hell with an aftermarket pump and a rewire you should have enough fuel without even needing an aftermarket FPR.

I don't recommend the bored out secondaries. After personally having a stock injector fail for no reason ,I think the cost involved for what you get is just not worth it.

You didn't mention if you're still on the stock pump?

 

i've been running 550cc primaries and RC engineering bored out 1300ccs secondaries with supra pump for a while now with no problems. made 340 whp @ 14.2 psi on my 99spec turbos. injector duty cycle at WOT is around 84%ish. which is still plenty since u shouldn't run anything over 15 psi on those.

stock injector setup 550/850 would only support up to around 12 psi safe tune. and 1600+ secondaries would be overkill for stock (including 99spec) turbos

 

Some threads from the Archives
https://www.rx7club.com/showthread.p...highlight=fuel
https://www.rx7club.com/showthread.p...highlight=fuel

Also more info in the FAQ thread stickied in this forum. Spend some time reading it.

 

stock turbos (even '99) and aim for 325 rwhp you don't need 1600's 1200 to 1300 RC bores would be fine.

 

Always overbuild your fuel system. Once you hit your goal you're just going to want more.