from the chart on the instructions it appears to be 6:1, do they make anything that is larger than 6:1 for the Sfmu? anyone know?
thanks
james

You can probably put a 12:1 disc in it. I can't see them being any different than the disc for the FMU.

yo Dino,
you know if the disks that are supplied the 3.62, 2.72, 2.47, 2.22 inch give me a 12 to 1 rise rate, i called vortech and the guy i talked to was kind of dumb.
thanks,
james

okay i dont get it, everyone says we need a 12:1 rise rate with stock injectors, but if you do the math it is actually closer to 6:1. this is how i see it.
0 boost 60 psi FP
5 boost 85 psi FP
10 boost 115 psi FP

so to get the slope of this line. you subtract 60 from 115 and you get 55 now you divide the 55 by 10 and you get the slope which is 5.5:1~ 6:1, so where the heck is everyone getting the 12:1 information? if we were using 12:1 disks our fuel pressure would be 180 psi at 10 psi boost!
am i missing something?
lates
james

I've always believed we have such a high rise rate to compensate for fuel pump deficiencies.. There's hardly a pump out there that could do a true 12:1 rise at 10PSI (and they're not cheap)..

Ok I have a problem...
I was running only like 31 psi at idle and 81 at WOT.
I was told that idle needed to be more like 45-47 with stage I HRC.
So I tried turning it up but the screw I was turning went all the way into the FMU before It got to the right FP???
I couldn't go any further...I had to back it back out to put the Washer with a little rubber seal in it and the locking nut......Do those have to be there also?

But anyway What do I need to do now, change the disc??
I don't know which one is in there now (whatever one was in there when I got it ..New)
Do I put the next size up in there or do I go smaller????

damn wish I had a fuel pressure gauge. Can you use it to tell if you filter is dirty? Cuz I haven't the slightest clue what condition mine is in right now.

Uhhhh I don't think you can tell if it's dirty..
so does anyone know what disc I should use now?
Go bigger or smaller??

you have a sfmu? if so there are 2 springs that control the idle pressure. one i believe has a range of like 10-50 and the other one from 60 up, you have to use that other spring, you might be using the one for the lower range.

I don't remember seeing two springs but I can't even get 50 psi out of the one I have for idle press. so that can't be right??
If I do need to change the spring can I but it??

The S-FMU comes with 2 springs. The short one is fine for low ratio disks. You need the longer spring for the higher ratio disks. Not any spring will do, you need the spring that came with the S-FMU. If you lost it, you can order a new one from Vortech for $6 plus shipping.


Corbin

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

See I don't know whuch ratio disc I am using and I don't know which one I am supposed to be using...All I know is that my idle press is at like 37 at idle when it is cold and when it warms it is a little higher but not at 50 yet..
at WOT it is like at 81-85 psi.

the disc I have in there now is the one that was in there when I bought it..

My a/f is saying it's real lean especially at WOT (all the way red)
I haven't hooked up the Corbin one yet cause I have bad 02 sensor so that is maybe why I am getting lean readings..huh????

You really shouldn't drive around like that. If you want some help...send me an e-mail with ALL of the info mentioned below.

Your max boost
Intercooled/non-intercooled
Injector size (stock or other)
Internals (stock or other)
Size of S-FMU disks that you have (diameters)
Size of S-FMU springs that you have (length)

Give me this and I'll come up with a solution for you. You'll need a metric allen wrench to open the S-FMU. I'm at "cbehnken@vt.edu"



Corbin

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

Hey thanks I will email you when I get off of work.
I am SnakeEyes8181@aol.com