crai6m4ck

At what point should I upgrade to 1300cc injectors? Should I do it on a motor as a reliability mod so that it lessens the chance of maxing out the duty cycle when I upgrade it later this month to Pettit highflow twins (15-20% better air flow)? If my motor and turbos were stock and I started modifying it at what stage should I install them?

thatoneguy

You need bigger injectors when you hit more than 85% inj duty cycle so you don't burn them out. For me, that was intake, dp, mp, cb.

rx7speed811

why do some people get additional injectors tapped in on top before the upper manifold? like the greddy elbow with the additional injector holes... could this be used as a more convenient alternative to pulling the whole fuel rail?

kwikrx7

RX7.com says that the stock fuel system can support about 380 flywheel hp which is around 320-330 rwhp but that's at 95-100% duty cycle. Usually 13 lbs of boost with all bolt-ons is the absolute max but should be done before this. Some have gotten away with even more hp on stock injectors - I wouldn't do it though.

rx7speed811

what about the greddy elbow injectors? would those be an effective alternative to larger injectors on the rail?

Lost Time

You could, but why not just replace the secondaries. It'll save you from having to by an inj. controller.

rynberg

If you get 1300 cc injectors, you MUST have an upgraded fuel pump as the stock pump might not be able to supply enough fuel. For fuel calculations, you can check the calculator on rx7.com or www.maxcooper.com.