I know the numbers aren't right I couldn't be bothered, it's the theory that I'm after. So here it goes. If our stock injectors flow 235cc @ 43psi, then the purpose of running the 110psi with the turbo is to make our stock injectors flow at say 500cc to compensate for the boost. So if I'm right on the above then if I get 440cc injectors then in theory I can run the fuel presure at say 55psi, which seems alot better to me then the super high pressure with the stockers. If this is right then what does each boost level need interms of fuel flow eg. 500cc @ 8psi and 600cc @10psi of boost. Because If this is right then wouldn't we have to reconfigure the fuel pressure for our own boost level and injector size. Also does this mean that HRC's external pump isn't neccesary any more(this is based on an old post about fuel pumps) making the intank pump the way to go.

yes, you are correct. fuel pressure and injector size could be different for different applications. the first number you start with for all of these equations is projected HP output. if your engine produces 150hp stock and you plan on boosting to 15 psi, then lets estimate hp output to be near 300hp. then you can calculate injector sizes and the required fuel pressures from there. there are also several solutions to the same problem. one person might want to run the higher fuel pressures with slightly smaller injectors, while another might go for the larger injectors in order to keep fuel pressures down a bit. it's all a matter of tuning and depends on if you're going to use a s-afc or not. most of the guys that use the smaller injectors at high pressure don't have the afc and don't need it. if you go with the larger injectors, you'll probably need one.

But running lower fuel pressures would be safer I think...no injector lock up, right..


l e o n

exactly. when i get my injectors i'm gonna try to size them to keep fuel pressure around 70-75 psi max. when fuel injectors try to open, they are trying to push back at the fuel that's pressing on them. if there is too much fuel pressure on the injector, it won't be strong enough to open and no fuel will flow. how's that for a lean condition?!?!!

since that is the case then then what what our stock injectors be flowing at that 110psi @ 8lbs of boost.

about 370cc/min