fast951

This is not rocket science here guys. When you go to a larger compressore (ie K27/6 etc..) you will need more fuel as you are flowing more air. The stock injectors will be running at 100% duty cycle, you can increase the fuel pressure to bandaid the fueling issue. In the old days, when options were very limited, we had to run higher fuel pressure to get by. When using the stock injectors and running high (> 3bar) fuel pressure you have 3 main issues to deal with: (a) injectors still running at 100% duty cycle. (b) fuel pressure is increased across the RPM even Idle and PT where you may not need it. (c) Any time your air flow changes (more boost?) you may have to adjust fuel pressure.

When tuning a car, there are lots of variables to deal with. The fewer variables, the more accurate the tune is, simple. Keeping the fuel pressure constant is a good thing!

Flying Dutchman

John , thanks for providing info. The question is if you really *need* to be running lean when using an K27/6 with stock injectors. E.g. when running 1 bar boost with a K27/6 at 3 bar FP and a appropriately mapped DME for that scenario ?

Thanks for insights.