ATI P1 355 stock motor specs (forged motor) 12lbs boost with 2 core IC. No FMU I was leaning towards 30 maybe?

 

I'd go bigger. Why not, if you getting new injectors anyways. Then you have room for modifications. Upper 30's or lower 40's. Just my .02$

 

I'd go at least 42#ers. This may be comparing apples to oranges but >> my stock supercharged 4.6L Cobra originally comes with 39#ers (with Ford's rating system) and it makes 8.5-psig boost. Because your engine is larger, it will need more air at the same boost level and with 12-psig boost, I'd go 42....

I'll be using low-z 52#ers in my TT 305.....

 

Becuase the spray pattern changes with fuel pressure. If he goes too big the pattern won't be as efficient. Of course a few pounds shouldn't make a big difference, just a warning not to go entirely overboard.

 

42s will make 500 Hp at 90% DC with a safe AFR(12.0), fuel pressure at 43psi.

So this actually depends on our expected Hp and the fuel pressure.

 

I don't know why I didin't think of this before. >> Gentlemen, bookmark the following webpage. It's awesome! It lists EVERY injector made, I believe. I found this about six months ago >>>

Electronic Fuel Injector (EFI) Flow Data Table

Also, at the very bottom of the page after all the different injector manufacturer's is a Peak Horsepower per Injector table! Don't miss it..

Willie

 

Actually, if you tune the ecm for the bigger injectors you wont have to lower fuel pressure to compensate for the bigger injectors, so you still have the same spray pattern. The ecm will just open the injector for a smaller amount of time(duty cycle).

 

Almost everyone, ford included rate their injectors at 3bar (43.5psi), what they run them at in the car is irrelevant.

Assuming that both the injector driver is able to make enough of a signal fast enough and the injector is able to react fast enough to open and close accurately to give accurate idle fueling. At very short dwells you'll find that injector spray patterns get messed up also.