2x fuel pressure

[Wulfgang]

Hey, I was just wondering if I could get around buying larger injectors by just raising the fuel pressure.

If flow goes up with the square root of pressure, then I should be able to get over 40% more hp headroom by doubling the pressure, right? So if my car makes 200 rwhp and I want to get to 300 rwhp without maxing my injectors, then I could just raise the rail pressure to 2 x 43 psi = 86 psi.

What I want to know is can the Walbro hold 100 psi reliably (86 psi + 14 psi boost)? I know some people run rising-rate fpr's that go this high, but this would be for a daily driver.

Or should I just shop for cheap injectors?

[Sil240]

why dont you just get Rx7 injectors???

[Joe]

anytime you go above 75psi for an extended period in an injector you risk damaging them. i forgot the exact terminology but its bad, and its not worth it. spend the extra money and get injectors for your setup. trying to save a few hundred dollars now would make you feel damn stupid if you destroy the engine.

[rbsileighty]

The SARD Racing FPR I have can go as high as you are looking for in pressure... the fuel pump you have can not though... do a search on google for 3si fuel pump and you should find some VR4 guy who tested a lot of pumps and shows what they can do at different pressures.

As far as your idea goes... I calculated at work (I work for Bosch Fuel Injection Development) that the 20's 270 injectors are about 290's or 300's at 3.5 bar... yet, still my advise would be to get the right size injectors. Even with the RX7 injectors you sacrifice targeting since the injector is slightly shorter. By the time you made a system that could reliably support 100 psi (lines, pump, fittings, regulator etc)... you could have bought 6 correctly sized injectors.

Take this with a grain of salt, but I'd imagine the issue in running such high pressures would be sticking the needle open... not a great problem to have...

Hope this helps...

[Wulfgang]

Sounds like good advice. Thanks, I'll try to find that link.