Cheers for your help guys. Spoke to the guy who will map the car today and he is happy with 850cc prim injectors.



I was hoping to not go as far as 17psi. I would have thought it would have made about 330 minamum at 15psi. What are peoples thoughts.



Scott

 

So single and make 400rwhp at 14psi.

 

I would but so far i m the man to catch in the uk with a twin and i still only have a stock fuel system and stock boost. Much to prove yet



Scott

 

yep, 330@15 psi is right in the ballpark

 

If you change the fuel pump and injectors do you need to change the fuel maps in the computer, or get a stand-alone comp?



From what I understand the computer runs the injectors on a percentage basis, for example: at a 70% duty cycle for the stock secondaries that is 595cc (.70x850cc).

If 1300cc secondaries are exchanged in, with a large enough pump to supply them, the computer is still telling the injectors to work at a 70% duty cycle, but now that is 910cc (.70x1300)?



If the computer does work this way is tuning the ECU fuel maps, or a stand-alone unit needed after installing larger injectors and pump?



I am not sure if I am right on this. Can someone with more expertise help out?

 

Power FC works that way. It references boost vs. rpm and that will give you a multiplier. This multiplier is multiplied (go figure) by the base map to give you how long the injectors open up per mSec.



You can get away with going from 550cc to 720cc injectors because the difference in cc is small...but 1300cc in a big *** jump from 850cc.



hope that helps.