I've been searching for over an hour now and I can't find my answer. What's the max CC primary fuel injector size, before needing a new primary fuel rail on a S4 T2?

 

2000cc?

there is no proper answer, both primary and secondary rails can support 500WHP+ which is about 6000cc worth of injector.

 

So the primary rail alone can handle 1000cc injectors. Reason why I ask is becaus I'm going to be doing a track only car.

 

then why do they sell them, to add more injectors? or just in use a FPR with dual Pressure bleeds.

 

fuel rails? because people like flashy bits that are hidden under the intake manifold.

actually it is more or less for ease of aftermarket line installations and deleting the FPR/PD.


even parallel lines are not required below 500whp.

 

I had 1000 and 2000's on my S5 TII and that was overkill.

Explain track only..and what you have done to the engine and why you need so much fuel?
If the stock set up was 4x550 then by rights you can go 4x2000.(big *** injectors) but you need to warrant it and support and control it.

 

Keg setup for 600rwhp w/ Bridgeport , adaptronic ecu w/ e85 tune, 72mm, reinforced block, side clearanced rotors, dual walbro 460lph fuel pumps etc...

 

then no, you need bigger rails.

E85 requires more fuel and you're borderline what the stock rails can flow even on pump gas.

 

Thank you RE. What would be a good brand rail to go with, if I need a bigger primary rail, then I know I'll need a bigger secondary rail too.

 

whats your thought on these?

Fuel System | Product Categories | Full Function Engineering

 

Everything FFE makes is top notch. So while I have no personal experience with that particular product, I have no doubts it will perform as advertised.