Originally posted by WydRyd
Porschefile, I run a Protomotive FPR & CHIP, 944Turbo injectors and twin 044 pumps (in series) in my Turbo'd Carrera. This setup requires the high fuel rail pressures to work, as it "over drives" the 944turbo injectors to flow enough for Stage 3 power levels (i.e: 550-600HP). Many tuners don't like to run such high fuel rail pressures as it puts a lot of strain on the EFI components, but it's been working fine for me for many years without any issues.
kupcar, you should really have two MATCHING fuel pumps, front & rear. I personally wouldn't run only one up in the rear, or in the front, unless you're running an aftermarket EFI with big injectors and need only the one big fuel pump.
Honestly, I really don't see that as being a very good route for over 400whp. Sorry, I'm not trying to knock on your setup. The stock 951 injectors are 37#, which equates to about 380cc. At ~400whp they are pretty much maxed out and upping the fuel pressure can only help so much. I put down 431whp and my a/f's were HORRIBLE. I only have the dyno chart from my 2nd run that day, which was ~426whp and my a/f's jumped up to ~13.5-14:1 above 5k rpm. Anyways, I had Todd retune the chips for some Siemens 55# injectors and the car still runs great. There is a small amount of surging at very, very light low rpm throttle situations but, it otherwise runs fine. I just don't get why people don't spend the extra few hundred for properly sized injectors and a retune to do it right the first time. According to Todd, he was saying the high pressure rising rate FPR is also necessary for it to function properly on the stock afm. That makes sense as the stock afm is well out of resolution above 400whp. I'm toying with the idea of either going to his MAP setup, going with an AEM, or trying out a piggyback (Greddy E-Manage Ultimate) and eliminating the afm with a MAP so that I can run a constant rate of 5bar instead. Anyways, I'd rather have more injector than is necessary and have some room to work with rather than running at the limit and risking something bad.