Thanks for explaining it. But what I don't understand is why the 400 bhp engine already needs 168 liter/hr.

My example of 350 bhp would require 350 x 0.6 = 210 lbs-hr, which is 33 gallon/hr, which is equal to 150 liter/hr.

But with 4x 803 injectors 350 bhp is possible I believe. And 4x 381cc/min is 1.52 liter/minute, so that would be 91 liter/hr.

The difference is quite big, so something doesn't add up. Do the 803 injectors actually flow more (due to a higher pressure?)? Or is the BSFC lower in that situation?

But in principle it is the difference between the pump fuel and the special fuel you are using. I understand the difficulty in getting that amount of fuel at that pressure. But are you seriously going to run at about 4 bar boost?