hehe, me agin :)

im trying to follow corbins page.

what im doing is adding 30lb (315cc) injectors and a vortech fmu in place of the stock injectors and hahn fpr on my hahn kit.

i know what fuel pressure i need at full boost, but what i dont know is what my idle pressure should be, or how to figure it out. need to know this so i know what ratio disc to use for the vortech fmu.

I tried following corbin's example, but i get lost b/c the example incorporates a SAFC, which im not using right now.

I know its not a simple ratio, unless i just dont know what ratio to use, but which formula will help me figure out what my idle pressure should be approx.?

thanks for any help...

I appologize if some of my recent responses on this topic have been too curt. I'm just burnt out on calculations. I've spent 5 1/2 years in college (mech. engineer) and now I'm 13 days away from graduation. I've lived those years in a sea of formulas and figures and I need a break. But I'm also a nice guy, so I got some numbers for you.

For a HRC stage II with stock compression, Vortech S-FMU, 315 cc/min injectors, and NO S-AFC:

I assumed a
BSFC = .525
HP = 275 at 9 psi boost
DC = .95 (a guess)

need 378.98 cc/min fuel per injector
at the asuumed DC, approx inj size is 398.9 cc/min

For a 315 cc/min injector to do that:
fuel pressure will be 33.4 psi at 0 boost (vac line on FPR unplugged)
fuel pressure will be 78.8 psi at 9 psi boost

a 5:1 disk should work for this. The S-FMU comes with a 5.4:1 disk. You could use that and get a bleed valve put on the FPR to fine tune. You will have to ask Vortech for a bleed valve (it was listed as an option), but I don't know anything else.

Corbin

'95 ESI-T
HRC+FMIC+ETC...

no, no, your replies have been helpful, i just havent had a math class for a couple semesters now, and went into shock trying to figure out the formulas, haha

Sorry to have been such a PITA, but you and especially your site has been extremely helpful!

Congrats on graduating, btw!!

and thanks again for everything, youve helped big time.

i had figured last night that a 5:1 disc would be what i want, but i still wasnt 100% sure what i should be idling at. i also assumed less hp, but was using .6 as my BSFC (assumed turbo cars would usually be .6-.65).

thanks again, im gonna get a sticker that says "Corbin-Tuned" ;)

i also realize w/o a SAFC, im just going to be using these numbers as a starting point...ive noticed that formulas are good for getting started, but arent usually dead on for each and every car.