I have heard of a few people on the board talk about raising their fuel pressure some to simulate bigger injectors and tuning the computer to allow it. Is this a feasible option to do until purchasing new injectors? If so, how do you do this? Is an adj regulator required?

With my mods I am assuming I am about 330-340 rwhp thru an M6. I have heard that stock injectors max out around 350 FWHP and a recent 0-70 run with DataMaster shows my injectors hitting 100-103% duty cycle at upper RPM's, this why I am wondering this.

 

340 rwHP thtough an M6 would indicate about 395 flywheel HP. With a mediocre brake specific fuel consumption of 0.50 #/HR/HP, you would be close to 100% DC.

Yes, when you increase the fuel pressure, the capacity of the injector increases by the square root of (the ratio of the new pressure, divided by the stock pressure).

For example, raising the pressure to 58psi, rather than the stock 43.5psi, would increase the injector flow by:

(58 / 43.5) ^0.5 = (1.3333)^0.5 = 1.1547

Stock injector capacity is programmed as 24.9 #/HR, so the new flow rating on the injector woud be:

24.9 x 1.1547 = 28.7 #/HR

That pressure would support 410 HP at 85% DC.

You would need an adjustable fuel pressure regulator to increase the fuel pressure. Going any higher than 60psi can be a problem with the stock Rochester Products ball/seat injectors, because high pressure can lock them closed.

 

Ok, I have since gotten 30# SVO's, which ran great, I think right at 84% duty cycle, but then I switched to E85, and now they hit 85% at 4300 and are maxed (100%) at 5100 RPM (hitting 109% at 6100). So I need more fuel then. Can I bump the pressure up enough, or do I need bigger injectors?

 

I figured I need around 39 or 40# injectors or bump fuel pressure to 66-67 psi to get the fuel needed. Is this too high to boost the pressure? I am trying determine the best route, 42# injectors or an adjustable pressure regulator?