I'm planning out my build for my dd...and I came up with the idea of running as much fuel pressure as possible (IE...static 65psi....20psi max boost=85psi)

Things to consider....

Walbro fuel pump's volume output decreases as pressure increases.

With a base pressure of 45psi and ~26psi I've seen a single in tank walbro do 535whp.

My "number" is 400whp....no more.

As I raise the fuel pressure...the pump is less efficient meaning it will heat the fuel in order to make the desired pressure. (This heat is baaaad!)

I plan to run an inline fuel cooler...either a heat sinked undercar setup...or a liquid cooled system. Also..planning on insulating the fuel rail as best I can from the engine.

The "theory" here is that by running higher pressure to my injectors...i get a better pattern (ive seen my 1000cc injectors on an injector tester!!! yikes!) as well as a bigger temperature drop (drop in pressure...drop in temp...think air compressor)

I went to RC Engineering's site and did the calc's...using .60 bsfc, 90% IDC's, 4 cyl, 500 crank hp, 80psi pressure (60base+20psi)... 650cc injectors.

My question here is... do you think I can bump the pressure anymore without causing undue problems? IE burning up fuel pumps...heating the fuel too much...running out of enough volume of fuel?

lmk your thoughts.

 

Ask JDogg about bumping up the fuel pressure with RC injectors, he and some others have seen a high failure rate at higher fuel pressures.

 

It's not worth the risk to run higher fuel pressures for improved fuel atomization. There are other ways to reduce CC temps: ie methanol injection, more efficient IC core, etc.

 

bah...well at least I tried.

 

When calculating fuel flow from an injector on a boosted application, you can only use the base fuel pressure. The pressure increase with boost is just to keep the pressure ratio across the injector the same. You still only have the effective fuel flow of the base fuel pressure.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by tony1 &raquo;</TD></TR><TR><TD CLASS="quote">When calculating fuel flow from an injector on a boosted application, you can only use the base fuel pressure. The pressure increase with boost is just to keep the pressure ratio across the injector the same. You still only have the effective fuel flow of the base fuel pressure.</TD></TR></TABLE>

i always figured that in wow. didnt know that. my lesson for the day. back to buffin the floor.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by tony1 &raquo;</TD></TR><TR><TD CLASS="quote">When calculating fuel flow from an injector on a boosted application, you can only use the base fuel pressure. The pressure increase with boost is just to keep the pressure ratio across the injector the same. You still only have the effective fuel flow of the base fuel pressure.</TD></TR></TABLE>

doh...i keep remembering and forgetting this...