Which FMU Disk

Hey Guys,
I've been working on getting my car back together for a couple months now, and finally getting into the last little bit of stuff...it originally started out as just an S-Trim install, and has now turned into heads/intake/MAF/T-body, etc, etc, install.

I'm planning to use the FMU at least initially, and I'm wondering which disk I should order for it - it currently has a 12:1 in it, so I know I'll have to change it.

Here's my setup - stock bottom end, ported aluminum Y303 heads, 1.7rr's, stock cam, E-bok intake, 36# injectors, 70mm T-body, 77mm MAF, Walbro 155lph (in-tank), and T-rex inline, Kirbin AFPR, plus some other typical stuff like long tubes, MSD ignition, etc. I'm actually running an MSD 6AL with the vortech boost retard wired together. I also have bought one of the Pro-M optimizers, and plan to tune with it and get me a wideband pretty qwk. I've already got a 2.95 blower pulley on with the stock 6.87 crank pulley...so I'm thinking that boost will be somewhere 10-12#.

Nevertheless, I've had some folks tell me to use the 4:1 FMU disk, but Vortech's website recommends 6:1 for 30-36# injectors, and 4:1 for 38-42#.

Should I play it safe and go with the 6:1, or do you guys think I would be okay running the 4:1?

Thanks!

Vortech wants u 2 b safe A/F wise.However u w/still b rich w/4:1 under boost, which is the only time the fmu works(effects fuel press) any ways...

Yeah, I know how the FMU works, and realize that it will only spike the pressure under boost....I think 4:1 is as small as I can go, right? If I thought I could get by without the FMU I'd do it....I'm just not sure with the 36#ers.

if your gonna use the FMU buy a 255 high pressure intank pump. the 155 won't keep up @ higher pressures.

You know, I see that I said 155 in my original post...not sure where my head was, but I actually have a 190 Walbro in the tank, along with the T-Rex inline.

Thanks for the replies! :)

Quote:

---

Originally Posted by Rreemo

Yeah, I know how the FMU works, and realize that it will only spike the pressure under boost....I think 4:1 is as small as I can go, right? If I thought I could get by without the FMU I'd do it....I'm just not sure with the 36#ers.

---

Vortech also has a 3:1..

Quote:

---

Originally Posted by midnight

Vortech also has a 3:1..

---

I had pretty much decided to go with the 4:1....wasn't aware that they made a 3:1 also....I wonder if I should go with that one instead of the 4:1?

Yes, i would go w/the 3:1..If u decide 2 buy another disc, I would buy the universal recal kit.It isn't much more $$ than a single recal disc & has all the diff discs(Recals)..Let me look in my stuff, i may have one & if so w/send u a PM...U could resale the rest of the disc's & recoup your$$ if i don't have one.....