Ive got the power I needed and I know my stock injectors are running above 80% dutys with the power Im running 300rwhp+.

And as a precaution I was wondering what would happen if I had the 850's enlarged to 1300s while still on the Pettit Unlimited ECU?
Seeing as the injectors are told what to do by the ECU, what would happen with the 1300's running the same 13psi? obviously the injector dutys will be down but will anything wierd happen? I know alot of people are gonna get on this and say, "just buy a Power FC!" but Im simply wondering this as a precaution so I dont run out of fuel on the setup Im running.

 

It won't work properly for the simple fact that the ECU doesn't know you have changed to bigger injectors and will still fire them the way it was programmed to do so with the 850's. Basically you'll run an injector that's 35% bigger at the same duty cycle, which means it'll be too rich, and that isn't good either. IF you don't want to run a PowerFC, and you are staying with the same turbos, you can run a HKS AIC, or a Greddy Rebic4, or any other MAP based pressure sensor additional injector controller to add more fuel with no problems with your Pettit ECU as long as it's an Unlimited chip, this setup has seen 11.1's-11.2's reliably with no problems.

 

ahh, I see.
And lets say I went the route of those Add. Inj. Controllers would I just get the Greddy Elbow, add the extra injector (size to add?) and the control the amount of fuel based on my A/F?
thanks for the insight!

 

Yes, basically that's it, I would recommend 2 additional 550cc's for your application, you won't need anymore than that for the stock turbo setup, even if you port the motor. That's more than enough fuel, also upgrade your fuel pump with a higher flowing drop in replacement like the Supra TT fuel pump.

 

If you need to lookup a reference as far as fuel capacity goes, you can use this as a reference:http://www.maxcooper.com/rx7/how-to/...tem/calcs.html