Ok after the recent downpore of info about timing and detonation lately I have some questions. I have two different fuel setup plans and I need help picking the right one. Let me start by saying that this is for running 15psi max daily. I've worked w/ the equations on Corbin's page many times and I know almost exactly how much fuel I need. My first plan was to stay w/ my 315cc injectors. I will get an inline pump that flows 40GPH (way more than I need) at 110psi. That will be in conjunction w/ my Walbro 255hp. At 15psi I need ~110psi fuel pressure. If I keep the same disk in the SFMU and leave the static pressure the same then I will have exactly the right fuel at full boost.

The next setup I am thinking about is to get 440's and run about 20psi idle pressure. Switch to the 3:1 disk and get the 75psi fuel pressure that I need at 15psi.

The 2 main reasons that I want to do the first setup is because I can be ready for 15psi by saturday and because I want to see how fast I can get it w/ such a simple fuel setup. The reason I want to do the second is because I have a cushion for boost spikes and I like lower fuel pressures.

Now I think I read in that huge detonation post about how running high fuel pressures does something to the pulse width and screws up timing. I'm not going to pretend like I know what I'm talking about w/ pulse width so that's why I'm posting this. So is it really unsafe to run that high pressure? Which would you do? Thanks for reading.

From what i know, fuel pressure alone has nothing to do with ignition timing. I believe every fuel injector has its limits with how much pressure they can take, i've heard not to exceed 120 psi. With larger than stock injectors, fuel pressures shouldnt ever get that high, if they do, then get the next largest size injector. I have heard that excessive fuel pressure can "lock open" the fuel injector, and it will constantly spray fuel. Duty cycles over 85% is where most injectors dont like to operate very well. Thats why our ECU is programmed to give fuel cut when it tries to go over that pulse width. Running a higher fuel pressure should not effect pulse withdth, at least not a great amount, if the pressure isnt excessive. If you are goint to run 15 psi, go with the 440's for sure. You can do it with 315's, but you will have to run really high pressures, and may cause some problems because of it. Not to mention lower fuel pressures can be safer on fuel lines, ect..

That's right. It was fuel cut that was the problem w/ the higher pressures. I knew there was some problem but couldn't remember what.