Could you provide the injector duty cycle % using this setup?
High - and bigger injectors will not necessarily help.
Here is what I have seen tuning the returnless DBW S2K with Kraftwerks and a stock fuel pump.
- You have around 50-54 PSI pressure in the tank, where the FPR is located.
- At the high 300 to low 400HP values you are losing about 10 psi along the fuel line from the rail to the tank.
- This means 40-44 PSI rail pressure
- At 10 PSI boost pressure this means pressure across the injector is 30-34 psi
A high flow fuel pump will do nothing in this case. Neither will larger injectors. You want a reliable 400+ you need a return line fuel system.
The Kraftwerks kits with the K-Pro dual adapter are making around 400 HP and are leaning out a little in the last 500-700 RPM. I suspected the stock fuel pump was also on its limits so on a test car here I installed a Kenny Bell Boost-A-Pump and upped the stock fuel pump voltage to 18V under boost. This gave me back about 1/2 a point AF at redline. The boost-a pump enabled me to run an in tank walbro 255 for my landspeed RSX making 650-750 HP all year.