Increase in fuel pressure from stock

[davidgboyle]

So the 440s on my Aristo 2J are not cutting it anymore and I am buying parts of a new fuel system over the winter so the spring can bring me a full new system with dual pumps and 720s.

My question is how many people here have increased the base pressure of their fuel system to accomplish slightly higher fuel delivery? My injectors flow 440cc at 43psi base pressure and with 20 psi of boost they flow 530cc which is not nearly enough fuel to handle 20psi. I am thinking of increasing the base pressure from 43psi to 55psi which means that my base pressure will give me injectors that flow 500cc and at 20psi of boost they will flow 582cc which will be good for roughly 18 to 20psi.

I know that everyone on here will say wow you need new injectors and your pushing the fuel system and your gonna blow your motor. I understand what I am doing and I will be getting bigger injectors, stock mkiv 550s whenever I can find some for sale NO ONE HAS THEM, I also understand that this is "dangerous" but I wont be boosting to 20psi for more than a few pulls at the strip. This method may sound like something new and stupid but people have been using FMUs in the import world for a while and the muscle car guys have been doing this forever.

Who's brave enough to admit that they have done this?

 

[tissimo]

If your injectors flow 440cc at 43 psi they flow 440ccs. Remember even with 20 psi of boost and the FPR raising the fuel pressure to 63 psi, the injectors are pushing against 20 psi of pressure so they still only are flowing 43 psi of fuel.

Yes, you can run higher base pressure to get a bit more fuel. You just have to balance the pressure vs pump flow as well. With the Walbro they still flow ok above 70 psi of pressure so you should be ok. (55+20 = 75) Of course its harder on your components, as I'm sure you realize.

 

[davidgboyle]

Tissimo, thanks for the response. I completely understand that this is being hard on the components, but old 440s aren't good for much and I am hoping to see a new fuel system under my Christmas tree complete with 720cc injectors.

 

[tissimo]

Tissimo, thanks for the response. I completely understand that this is being hard on the components, but old 440s aren't good for much and I am hoping to see a new fuel system under my Christmas tree complete with 720cc injectors.

Haha yea, racing is hard on the car but we do it anyways