does anyone know how you tell what ratio fmu u have? From what i found, the higher the ratio, it says uses a lower cc injector. Im going to guess this means the higher the ratio, the more fuel and the smaller injector you can use…which is why everyone runs 12:1’s on honda’s and such…my brain is fried…thanks for any info
the way i always understood it was a 12:1 fmu will raise the fuel pressure 12psi per 1 psi of boost
You need to open the FMU up and see what calibration disk is in the unit. Depending on how many holes are in the disk-then you can tell what fmu you have…
Originally posted by fiveohmatt
the way i always understood it was a 12:1 fmu will raise the fuel pressure 12psi per 1 psi of boost
That is correct.
Alot of tuners put bigger injectors in and remove the fmu. :dunno:
Originally posted by TTNOTCH
You need to open the FMU up and see what calibration disk is in the unit. Depending on how many holes are in the disk-then you can tell what fmu you have…
holy shit :eek2: long long time no see
Originally posted by HaNnIBaL64
holy shit :eek2: long long time no see
Just on a break…
Originally posted by TTNOTCH
Just on a break…
hope your out this summer then 
Originally posted by fiveohmatt
the way i always understood it was a 12:1 fmu will raise the fuel pressure 12psi per 1 psi of boost
so if you run 20psi on a 45psi initial setup…full boost will be 285psi??? I could be understanding this wrong…
Originally posted by gearhead
so if you run 20psi on a 45psi initial setup…full boost will be 285psi??? I could be understanding this wrong…
Yes but chances are if your running 20 # of boost you will have larger injectors whitch would mean a smaller ratio fmu. Ex. 8-1, 6-1, 4-1, 3-1.
good thread
Originally posted by gearhead
does anyone know how you tell what ratio fmu u have?
the one i had before had 3 numbers stamped in the bottom…
I took it apart and it has nothing stamped or written on it. It just has the disc and a ring around it.
Still don’t know…but from lookin at pictures, a full disc is 12:1, (what i have) disc with a small ring around it is 10:1 and so on…the smaller the disc, the less fuel rise.
Originally posted by sonic03snake
Yes but chances are if your running 20 # of boost you will have larger injectors whitch would mean a smaller ratio fmu. Ex. 8-1, 6-1, 4-1, 3-1.
so big boost on high fmu ratio’s is bad? Im thinking the pump would have to max out at some point…
most people tend to run the 12:1’s on honda’s with stock injectors and either a stock or upgraded pump.
running a 12:1 with say dsm 450’s or larger, would run really rich and might be hard to get a good idle.
whats the app that this is going onto?