Hey guys...wondering if you could help me out. My buddy and I have been talking about which would be the best ratio to go with on my other car for the FMU. Its a '99 SC solara and I just did a return style fuel system on it. I've got 318cc with a 190 Walbro right now, but will need to upgrade to the 255 to do this. I'm running 7lbs. of boost with two meth nozzles (175ml and a 60ml with a 50/50 mix). Currently my fuel pressure is the constant ~42ish throughout the power band but goes down approximately 4psi at WOT. I guess my question is, when determining which disk to get (we're thinking either the 6 or 8:1), do you add the figure you get when you multiply lbs. of boost times the ratio number (i.e. 7lbs. of boost x 6 = 42) to your current fuel pressure? or do you just multiply lbs. of boost to the ratio in order to get the desired fuel pressure under boost that you want?

I hope that makes sense?...thanks in advance.

**318cc = 30lbs. per hour injectors

 

So you did a return style without an afpr and have not done the 255 walbro? Too many variables in the setup, what are you using safc, emanage?. I would do walbro 255 with an afpr 1:1 rising rate and check the afr from there. Its not so much as what your fuel pressure is saying unless it's really high, it's what your afrs are saying at wot, either you have enough fuel or you don't.

 

yeah, forgot to mention that....the rails I put on have a fpr (non adjustable) and I left the stock one in the gas tank. Using the Neo to tune with and its currently maxed out at +50 from 3500 to around 5k RPM to get a 12:1 A/F ratio. the FMU will allow me to reduce the huge +50 down to the +20's so I can get some timing back.

 

let me put this another way, what disk are you guys using for the FMU to get the desired outcome based on your boost/injector size?

 

Personally I've got a walbro 255HP, aeromotive 13301 fpr, stock FMU that comes with the stillen kit, and the stock FPR gets removed. Tell dawgz I said wasup.

 

No FMU Properly sized injectors plus EMU tuning=WIN.

 

lol...will do

 

just out of curiousity, anyone know what ratio the stillen fmu kit comes with? (6:1, 8:1)?

If you don't know the ratio, do you know how much fuel pressure you're getting @ WOT with it?

 

6:1