Fmu Vs 1-1

Mathewrussell52

Registered
When looking in to purchasing a fmu for my turbo build. I see that RCC sells a 1-1 with all the gen 2 kits. Is one better than the other. I want to run E85 when I do some moderate engine mods will I need a fmu or will a 1-1 push enough fuel.
 
If you have a gen 2, use a 1:1 and flash the ecu for tuning.

Gen 1, you'll need an fmu for up to 10psi, and secondary injectors if you want more then that.
 
When looking in to purchasing a fmu for my turbo build. I see that RCC sells a 1-1 with all the gen 2 kits. Is one better than the other. I want to run E85 when I do some moderate engine mods will I need a fmu or will a 1-1 push enough fuel.

Gen 2 kits from RCC come with a 1:1 regulator, the FMUs come standard in the Gen 1 kits . . .
 
So there is not gain from a fmu? What can factory injectors handle?

The FMU artificially raises (ramps) the fuel pressure to give an injector more range and the ability to supply sufficient fuel for the requirements of a blown engine; there are limits, however. To your question: are you talking about a Gen 1 or Gen 2 Busa, and, are you asking about pump fuel or E85?
 
So there is not gain from a fmu? What can factory injectors handle?

It has nothing to do with gains. It has to do with how the exu does fueling, and injector size as well.

On the gen 1, the ecu does not recognize and can't fuel according for boost. Because of that you need to mechanically fuel the engine. When I mean by that is an fmu is a 1:6 ratio regulator. For every one pound of boost, it increases fuel pressure 6psi. So on a stage 1 gen one hayabusa that means under boost with 8psi, the boosted fuel pressure should be around 90psi. By raising the pressure so high allow for the small stock injectors to flow enough for the turbo fueling, and also it a back door for getting around ecus that don't recognize boost.

The gen 2 ecu on the other hand can recognize and compensate for boost with injector pulse width. Don't need sky high fuel pressure to mechanically fuel with them.
 
"The gen 2 ecu on the other hand can recognize and compensate for boost with injector pulse width. Don't need sky high fuel pressure to mechanically fuel with them."
If its flashed for boost , and it works very well
for E85 you may want to upsize the secondary injectors or be limited to about 250hp
 
The FMU artificially raises (ramps) the fuel pressure to give an injector more range and the ability to supply sufficient fuel for the requirements of a blown engine; there are limits, however. To your question: are you talking about a Gen 1 or Gen 2 Busa, and, are you asking about pump fuel or E85?
"The gen 2 ecu on the other hand can recognize and compensate for boost with injector pulse width. Don't need sky high fuel pressure to mechanically fuel with them."
If its flashed for boost , and it works very well
for E85 you may want to upsize the secondary injectors or be limited to about 250hp
It has nothing to do with gains. It has to do with how the exu does fueling, and injector size as well.

On the gen 1, the ecu does not recognize and can't fuel according for boost. Because of that you need to mechanically fuel the engine. When I mean by that is an fmu is a 1:6 ratio regulator. For every one pound of boost, it increases fuel pressure 6psi. So on a stage 1 gen one hayabusa that means under boost with 8psi, the boosted fuel pressure should be around 90psi. By raising the pressure so high allow for the small stock injectors to flow enough for the turbo fueling, and also it a back door for getting around ecus that don't recognize boost.

The gen 2 ecu on the other hand can recognize and compensate for boost with injector pulse width. Don't need sky high fuel pressure to mechanically fuel with them.
Thanks for the knowledge. It gets me in the right direction.
 
I believe gen 1 can use a 1:1 but only with bigger injectors and something like a power commander with hub or pcv.

Stage One for a Gen 1 with a 1:1 uses stock injectors. Yes, you can use bigger injectors if you wish, but it is not necessary unless you plan on going over 280-300 . . .
 
Stage One for a Gen 1 with a 1:1 uses stock injectors. Yes, you can use bigger injectors if you wish, but it is not necessary unless you plan on going over 280-300 . . .

I was always under the impression that the gen 1 needed more injector thAn stock,i learned something new today!!! Thanks for clearing that up frank!!!!! That's why I love this site.
 
He ment gen 2 stage 1...

Makes total sense now lol. Thanks for clearing that up rob. Do the gen 2 have the ability to run 1:1 because of the fueling algorithimum and because it has more range with 8 injectors?

Right, thanks Rob. Gen 1, FMU; Gen 2, 1:1. With the Gen 2, it is the range eight injectors afford, and the ability to have all eight firing at the same time with some ecu changes. Boost fueling in the Gen 2 ecu works well as the Gen 2 RCC kit allows it's own map sensor see boost levels, giving the tuner the ability to fuel at the different levels if needed.
 
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