Fuel Pressure formula

[leoboy]

Hey guys I found this formula in a book. Its to calculate for new fuel pressure for bigger injectors.
2
New Fuel press.= (New fuel injector flow (in cc)/Old fuel injector flow (in cc))(stock fuel pressure)

So that would mean that if I wanted to run 630cc injectors from my previous 450cc, and my stock fuel pressure being 37 psi, that would put my new fuel pressure at...like...72 psi or something. Does this sound right? Am I missing something? Because that sounds really high. Need some clarification here, can I get some help here please. Thanks guys.

 

[GVR4592]

What exactly are you trying to do? If you just want to get a little extra out of your 450's you can increase the pressure to 50-55 psi. If you want to swap to larger injectors you don't need to make fuel pressure changes.

 

[turbosax2]

(630/450) * 37 = 51.8

For more injector math, see here:
http://www.dsmtuners.com/forums/tun...279449-fic-850s-simple-deadtime-question.html

 

[leoboy]

Its actually:

(New injector Flow (cc)/Old injector Flow (cc))(New injector Flow (cc)/Old injector Flow(cc))
(Stock Fuel Press.)=New Fuel Press.

So its:

(630cc/450cc)(630cc/450cc)(37psi)=72 psi ("New required PSI")

Sound right? Am I reading too deep into it?

Oh, and I am shooting for 400 HP. I am going for bigger injectors because I want to stay within a 80%-85% duty cycle. But , really, what should I do as far as injector sizing and fuel pressure?

 

[tristanmb81]

If I want to push my stock injectors to max, then I would have to increase my fp? Would I be adjusting w/ or w/o vacuum at the fpr?

 

[GVR4592]

You would test with the vacuum line off. Your fuel pump isn't going to keep up at those pressure's, it can't keep up with stock pressure. Even if you had a Walbro 255hp you wouldn't want to go much over 55 psi base fuel pressure. I think you should just buy some new injectors.

 

[leoboy]

Thanks turbosax2, for that cool link, everythings clear now. Thanks again fellow DSMers.

 

[steve]

Here is another one for you.
RC Fuel Injection

 

[leoboy]

Awesome link Steve!! Thank you so much o "mighty DSM Wiseman."