Why do these FMUs look different?

 

someone has to know why the fmu on the left doesn't have a screw on top and whats with the scew where the vacum line nipple should be...???

 

I have absalutely no clue what I am looking at. What is an FMU? (Sorry for not having an answer to your question)

 

Turn one 90 degrees and they look about the same, minus the slightly different screw opposite the nipple. They are similar except that the mounting bracket is on a diff side, too.
Then again, I'm like tofuball - I don't know what the hell an FMU is in the first place hehe I'm jus tryin to help

 

Nah, also: one has a bolt in the center while the other does not.

 

FMU AKA FuelManagementUnit AKA FuelPressureRegulator?
the one on the right appears to be adjustable. i'm not quite sure why the nipples are located differently.
on the adjustable one, you can see the hex screw in the middle and a jam nut surrounding it. it has to be adjustable.....whatever it is.

 

Yep, the one on the right is adjustable.
The one on the left isn't.


-Ted

 

finally.. TED speaks... knew one was adjustable and one wasn't... i just diddn't know what the hell they were!!!!

 

LOL!!! ok ok...
They are obviously identical except one can be adjusted and one can't.
I want to know why left one isn't adjustable like the right one. Why have a FMU if you can't adjust the fuel curve??
Who makes these this type of FMU and what is the ratio of the non-adjustable one (since it apparently can't be changed)?

The left one came off my silver RX-7. It was on there when i bought it. I no longer need it because I have an E6K EMS. I'm just tying to understand the old setup a little better.
The right one is off my friend Mike's turbocharged B16 honda civic DX. He too is switching to a stand alone EMS.

Hope that's a little more specific!

 

Oh, and a FMU is what you use to turbocharge a factory non-turbo car! It increases fuel pressure as it sees positive manifold pressure. Thats why they have nipples for vacum lines. They are VERY useful for cars that boost below 10 psi.

Check this out if your still clueless:
http://www.brownsword.ca/fmus.html

 

Yeah, I haven't messed with those things in a looong time, but you're exactly right.

I think the differences is that one requires the stock FPR, while the other one can replace the stock FPR.

I think the non-adjustable one (left) requires the stock FPR and you just insert it after the stock FPR.  It only kicks in when it sees boost.

The other adjustable one can be adjusted for base pressure (middle screw) and (I think) you connect a piece of hose to adjust for ratio adjustment on the offset fitting.

These are either Paxton, Cartech, or BEGI FMU's.


-Ted

 

Thanks Ted. Thats makes sense. I searched everywhere but I dont think anyone makes this model anymore. I did find this on

www.superchargeronline.com/forum

"Most FMU's that come in a supercharger kit are preset and are not adjustable. Vortech's have a washer inside the FMU over the piston. By switching to a different thickness washer you can change how far down the piston goes and thus, how far the pressure increases."

So I guess the guy got it from someone parting out a supercharged car or something.
Still seems like dumb idea to me. They should all be adjustable like the right one so they can be used universally.

Ryan

 

Yeah, these are mega-popular in the Honda crowd. They're really just a band-aid fix in place of a V-AFC (S-AFC, preset for Hondas with a built-in VTEC controller)

 

Actually they are used on supercharged vehicles, they are usually a static 1:1 rising rate. People have been using them on honda's but they have been known to cause mad fuel delivery problems. They aren't designed to be used with turbo! Most the time you will find them on anything with a supercharger, ecspecially mustangs and thunderbirds-(ford)

 

Not true. They are known and proven to lean out when there is a transition from vacuum to boost- I have/had dyno plots to prove this, where a guy had an fmu that came with a popular honda kit, when it would hit 10psi of boost it would lean out until the fmu compensated. Hence the reasons why they are great for a supercharger, no sudden transitions, its a more gradual transition!

 

Kai- yea, your right. Its because $150 for a FMU looks a whole lot better then 1k for a EMS that requies a whole lot of tuning knowledge. What works works...

rx-rated- I beleive it, Mike's civic would hesitate for a second before it would boost. He finally bought a V-AFC to smooth everything out and fine tune it...it was a badass car on a budget