I've been doing some searching to find out at what psi the fuel NEEDS to be upgraded. I haven't been able to narrow it down to a solid answer. I have an s4 turbo with rb rev tii exhaust, with an fcd, and ported wastegate. Now I know the s4 turbo is insufficent after 12psi ish or is it 15psi? At what psi does the fuel need to be upgraded? And what psi would be SAFE on the s4 turbo. I dont want to put the psi in the danger zone and just want to be sure. The reason why I want to know this is because my car boosts at 6psi which is great, but the catch is at around 5.5k rpm it starts to creep till about 8psi and I think ive seen as high as 9psi in 4th.

 

Subective quesion because there is no surefire way to be sure that all of you fueling is in tip-top shape.

Correct answer would be to put a wideband on it and ENSURE the fueling is safe, although some have ran up to 10 PSI though with little harm.

 

maybe throw in a fuel management system too with bigger injectors and a walbro?
thats the route I was gonna go for safety purposes

 

Please stop thinking boost = power.
It's not.
Power = FLOW.

The stock fuel pump (at FULL VOLTAGE) is good for 250bhp or about 220 - 230 at the wheels SAFELY.
MOST OF THE TIME, it's not the fuel pump that's out of capacity - it's NOT ENOUGH VOLTAGE GOING TO THE FUEL PUMP.
That stock fuel pump resistor relay is BAD by now.
Rewiring the fuel pump power wire is a GOOD thing.

Upgrading to a large fuel pump is always a GOOD thing.
If anything, you might take a hit in fuel economy.
Fine tuning the fuel (i.e. S-AFC, standalone, etc.) will get back your gas mileage.


-Ted