Vortech fmu opinions

[T-Punk]

ok im looking into ther 12.1 fmu from vortech. i figure its a name i know so it might be a good unit. in you honest opinion for 100 dollars is it good unit. are there any other units that are decent for about the same price.

[Wicked 3800 V6]

The 12:1 is a ratio, they also come in 10:1, 8:1, 6:1, 5:1, 4:1, you see the idea. Some also offer adjustability (Cartech, some Vortech), or digital (aeromotive?), and you can always add a bleed-screw to a 12:1 to let it see only 1/2 the boost, and regulate like a 6:1, etc.

You need to assess which unit you need based on the blower / turbo that you're running, how much boost you need, and perhaps diagnosis using an FPG. You WILL need fuel, it's just a question of which FMU, which fuel pump and injectors if needed.

[Ironman24]

Whatever you get make sure it's adjustable. I had a 12:1 disc in my FMU and it was WAY too much fuel. The high psi would lock up the injectors aorund 4500 rpm. I dropped it back to a 6:1 disc and that solved the problem. ATI also makes a very nice adjustable FMU that you can change with a allen wrench on the fly without taking it apart.

[Tiago]

tahts a huge ratio lol

[mattsv6]

i run 10-1 reference nad it is dead nuts. i think you would really like the cartech one too man. that thing is soo asy too adjust. and it also is an afpr. you can adjust it too whatever you need by hand or allen screw.

[slow]

why run a fmu, why not just tune for larger injectors whenever hptuners comes out?

Ryan.

[mattsv6]

cause you still need too add fuel. too much fuel and not enough inject or wil;l cause the injectors too go static and not flow enough fuel. will go lean and break stuff!!

[slow]

Originally posted by mattsv6:
cause you still need too add fuel. too much fuel and not enough inject or wil;l cause the injectors too go static and not flow enough fuel. will go lean and break stuff!!

will your maf not take care of the added air flow, if you have the injector to flow enough fuel?

Im fully aware of the go lean, and break stuff... thats why im going with svo 42# and a hotwired walbro 255 intank setup, for my vortech install. But it is on a LS1

Im just trying to learn more about the V6 motors, as i would like to put a turbo on a friends car, and wondering why a fmu is needed?


Ryan.

[Wicked 3800 V6]

Because the MAF can only accomodate "so much", particularly on the stock fuel pressure. You know the principle of an FMU, right? Adjusts the fuel pressure in proportion to boost. Sort of a little invisible extra fuel help on the top end. That's why many people call it a bandaid -- over-stresses things with high pressure. Bigger injectors and a fuel pump are, of course, the best way ... but I'd like to see you get that to work well. Props to those who have done it!

[slow]

its really not possible now, to the mainstream, without a real tuning package to edit all of the tables.

Thats is why i said when the hptuners comes out. I do understand how the fmu works, and that is why i understand to avoid them, if possible, as 80+ psi injector offset (rail to manifod) is a good way to lock them up, and have the injector fail. I know with stock programming, it is necessary to run a fmu, that is what they were designed for. But i was wondering what kind of power you can get with just the maf reading the extra air, with a boost referenced fuel system.


Ryan

[mattsv6]

you need too run higher lbs per hour fuel because you need the extra fuel. the smaller injector wont flow enouh fuel though it too accomodate the increased need. youll see if you dont trust me.

[slow]

why do you "need" to is my question.

Will the maf not support the extra airflow, and max out? IF so, then yeah, it is needed. If not, why is it needed, with large enough injectors installed. (36, 42's 57's ect)

Trust me, i know you NEED large enough injectors, and have worked on enough blown motor applications to know what is NEEDED, im trying to learn the WHY for this particuliar vehicle?

But instead, im getting responces like i am a newbie, and your blowing off my real question, of is it needed, if you have tuning, large enough injectors, and a boost referenced fuel system.

Obviously this will only work for cars, that can be truly custom tuned with the hptuners program.

Ryan.

[HAZ-Matt]

Originally posted by slow:
why do you "need" to is my question.

Will the maf not support the extra airflow, and max out? IF so, then yeah, it is needed. If not, why is it needed, with large enough injectors installed. (36, 42's 57's ect)

Trust me, i know you NEED large enough injectors, and have worked on enough blown motor applications to know what is NEEDED, im trying to learn the WHY for this particuliar vehicle?

But instead, im getting responces like i am a newbie, and your blowing off my real question, of is it needed, if you have tuning, large enough injectors, and a boost referenced fuel system.

Obviously this will only work for cars, that can be truly custom tuned with the hptuners program.

Ryan.

Yes, you do not need an FMU if you have a fuel pump and injectors that can support the fuel flow you need, and you have a way to edit your PCM.

[T-Punk]

would this work any better than an fmu? i have been looking at getting the walbro fuel pump, bigger injectors and the programmer from magnus and those guys anyway. So how much work would be involved on the programming side to get this to work instead of using the FMU. If its really hard ill go with the cartech because i like the idea of an easily adjustible FMU over the set ratio i was lookin at. The reason i was looking at the 12.1 is that is all i can find on E-bay. thanks for all the info so far.