# ID'n vortech fmu ratio.. **URL:** \ **Category:** PittSpeed Off Topic\ **Created:** [March 11, 2004, 1:00pm UTC](https://forums.speedlife.net/t/idn-vortech-fmu-ratio/164733 "2004-03-11T13:00:14Z")\ **Posts on this page:** 15\ **Page:** 1
**Author:** ![imported\_gearhead](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/imported_gearhead/32/5957_2.png) [@imported\_gearhead](https://forums.speedlife.net/u/imported_gearhead)\ **Post date:** [March 11, 2004, 1:00pm UTC](https://forums.speedlife.net/t/idn-vortech-fmu-ratio/164733/1 "2004-03-11T13:00:14Z")
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 ---
**Author:** ![fiveohmatt](https://avatars.discourse-cdn.com/v4/letter/f/97f17d/32.png) [@fiveohmatt](https://forums.speedlife.net/u/fiveohmatt)\ **Post date:** [March 11, 2004, 2:52pm UTC](https://forums.speedlife.net/t/idn-vortech-fmu-ratio/164733/2 "2004-03-11T14:52:46Z")
the way i always understood it was a 12:1 fmu will raise the fuel pressure 12psi per 1 psi of boost ---
**Author:** ![TTNOTCH](https://avatars.discourse-cdn.com/v4/letter/t/6a8cbe/32.png) [@TTNOTCH](https://forums.speedlife.net/u/TTNOTCH)\ **Post date:** [March 11, 2004, 7:00pm UTC](https://forums.speedlife.net/t/idn-vortech-fmu-ratio/164733/3 "2004-03-11T19:00:49Z")
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… ---
**Author:** ![sonic03snake](https://avatars.discourse-cdn.com/v4/letter/s/898d66/32.png) [@sonic03snake](https://forums.speedlife.net/u/sonic03snake)\ **Post date:** [March 11, 2004, 7:08pm UTC](https://forums.speedlife.net/t/idn-vortech-fmu-ratio/164733/4 "2004-03-11T19:08:00Z")
> _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.😃 ---
**Author:** ![sonic03snake](https://avatars.discourse-cdn.com/v4/letter/s/898d66/32.png) [@sonic03snake](https://forums.speedlife.net/u/sonic03snake)\ **Post date:** [March 11, 2004, 7:09pm UTC](https://forums.speedlife.net/t/idn-vortech-fmu-ratio/164733/5 "2004-03-11T19:09:36Z")
Alot of tuners put bigger injectors in and remove the fmu. :dunno: ---
**Author:** ![HaNnIBaL64](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/hannibal64/32/5954_2.png) [@HaNnIBaL64](https://forums.speedlife.net/u/HaNnIBaL64)\ **Post date:** [March 11, 2004, 7:20pm UTC](https://forums.speedlife.net/t/idn-vortech-fmu-ratio/164733/6 "2004-03-11T19:20:18Z")
> _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 ---
**Author:** ![TTNOTCH](https://avatars.discourse-cdn.com/v4/letter/t/6a8cbe/32.png) [@TTNOTCH](https://forums.speedlife.net/u/TTNOTCH)\ **Post date:** [March 12, 2004, 1:31pm UTC](https://forums.speedlife.net/t/idn-vortech-fmu-ratio/164733/7 "2004-03-12T13:31:27Z")
> _Originally posted by HaNnIBaL64_ > **holy shit :eek2: long long time no see** Just on a break… ---
**Author:** ![HaNnIBaL64](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/hannibal64/32/5954_2.png) [@HaNnIBaL64](https://forums.speedlife.net/u/HaNnIBaL64)\ **Post date:** [March 12, 2004, 1:33pm UTC](https://forums.speedlife.net/t/idn-vortech-fmu-ratio/164733/8 "2004-03-12T13:33:36Z")
> _Originally posted by TTNOTCH_ > **Just on a break…** hope your out this summer then 😃 ---
**Author:** ![imported\_gearhead](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/imported_gearhead/32/5957_2.png) [@imported\_gearhead](https://forums.speedlife.net/u/imported_gearhead)\ **Post date:** [March 14, 2004, 6:34am UTC](https://forums.speedlife.net/t/idn-vortech-fmu-ratio/164733/9 "2004-03-14T06:34:13Z")
> _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… ---
**Author:** ![sonic03snake](https://avatars.discourse-cdn.com/v4/letter/s/898d66/32.png) [@sonic03snake](https://forums.speedlife.net/u/sonic03snake)\ **Post date:** [March 14, 2004, 7:04am UTC](https://forums.speedlife.net/t/idn-vortech-fmu-ratio/164733/10 "2004-03-14T07:04:20Z")
> _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.😃 ---
**Author:** ![Darkstar](https://avatars.discourse-cdn.com/v4/letter/d/b487fb/32.png) [@Darkstar](https://forums.speedlife.net/u/Darkstar)\ **Post date:** [March 14, 2004, 12:36pm UTC](https://forums.speedlife.net/t/idn-vortech-fmu-ratio/164733/11 "2004-03-14T12:36:29Z")
🆒 good thread ---
**Author:** ![BETRAYED93](https://avatars.discourse-cdn.com/v4/letter/b/ed8c4c/32.png) [@BETRAYED93](https://forums.speedlife.net/u/BETRAYED93)\ **Post date:** [March 14, 2004, 10:51pm UTC](https://forums.speedlife.net/t/idn-vortech-fmu-ratio/164733/12 "2004-03-14T22:51:18Z")
> _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… ---
**Author:** ![imported\_gearhead](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/imported_gearhead/32/5957_2.png) [@imported\_gearhead](https://forums.speedlife.net/u/imported_gearhead)\ **Post date:** [March 15, 2004, 12:17pm UTC](https://forums.speedlife.net/t/idn-vortech-fmu-ratio/164733/13 "2004-03-15T12:17:44Z")
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. ---
**Author:** ![imported\_gearhead](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/imported_gearhead/32/5957_2.png) [@imported\_gearhead](https://forums.speedlife.net/u/imported_gearhead)\ **Post date:** [March 15, 2004, 12:18pm UTC](https://forums.speedlife.net/t/idn-vortech-fmu-ratio/164733/14 "2004-03-15T12:18:28Z")
> _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… ---
**Author:** ![germ](https://avatars.discourse-cdn.com/v4/letter/g/4da419/32.png) [@germ](https://forums.speedlife.net/u/germ)\ **Post date:** [March 15, 2004, 2:20pm UTC](https://forums.speedlife.net/t/idn-vortech-fmu-ratio/164733/15 "2004-03-15T14:20:39Z")
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?