Fuel Management Unit...

I sprung a nasty leak from my SC on Fri... leaking from the seals/rings on the unit. I found a great new speed shop locally and he was willing to squeeze me in to reseal the SC.

While he was under there we added a 10:1 FMU. I cannot remember the name of who makes the unit. I think it was HKS or Vortech, I will ask him on Monday.

I feel like the VX goes into boost much smoother and has a tad more power when in boost. I also have noticed that my weird idle for a sec at startup in the mornings has vanished. Seems to feel over all smother. I am going to go get it dyno'd again soon to see if the curve when I am in boost has smoothed out and if it is running richer now as I was running a bit lean.

Over all I am very happy... so far with this mod, then again I have only got to drive it for a day.

Some photos of the unit, pardon my dirty azz engine, it is getting cleaned soon.

http://www.vehicross.info/gallery/da...humbs/FMU2.jpg http://www.vehicross.info/gallery/da...humbs/FMU1.jpg

In a nutshell, the FMU adjusts fuel pressure when the boost comes on, regulating it at normal levels during normal operation and dramatically increasing it on demand. It is purely a mechanical device, using different sized disks inside the unit to alter the pressure at which the FMU takes effect. This makes it relatively easy to install and adjust.

FMU allows the car to run normally on a small injector, but can also increase the rail pressure under boost which, in turn, forces more fuel through the same size orifice. The fuel that the FMU adds has a direct relationship to the boost pressure.

The Pressure ratio determines how much the fuel pressure is increased per psi of boost pressure. A 12:1 FMU, for example, will increase fuel pressure by 12 psi per psi of boost. It is typically recommended that a 10:1 or 12:1 FMU be used in order to ensure that the A/F mix will not be lean.

Noice..just make a bracket for it now, can't have something like that bouncin around with zipties.

MMMM...Alien technology...flying saucer :homer:
In all seriousness, Looking forward to seeing the numbers/curve.Also, was the part itself (w/o labor) co$tly?,instalation, plug & play or complex?
Also,also, what were the symptoms w/ leaking s/c?
TIA, Ldub

wouldnt adding addition pressure to the fuel rail increase teh stress on the fuel line?
or is it so little its it doesnt matter?

i remmeber that when i on the rx7 forums they were talkin about a fuel pressure regulator. they modified it to increase fuel line pressure. is this basically wat ur talkin about?

Our FPR is already adjustable and since the injectors don't stay open any longer, there is minimal advantage to increasing the pressure, even momentarily. If you adjusted the stock FPR to a higher pressure, the stock ECU keeps the injectors open the same length of time at low speeds and increases it high speed/load which is very similar to what you are doing, that is why there is a pressure connection on our regulator. More boost causes higher pressure. I look forward to the Dyno scans.

I'm interested in the numbers, too. The Greddy E-Manage might do what we need in order to run more boost.

Ldub...

The unit was 200 and he charged me 142.50 for the install. Other than that I have no idea how hard the install was as I was at work at the time of installation.

The symptoms of my leaking SC were when I popped the hood I had gear oil all over my the front of the cone and around the bolts, look really, messy. Also I had oil trapped in that little square on top of the charger were the two seals connect.

I had heard allot of whining from the motor and it just did not feel right and was slower in boost.

-Dave

So you had a S/C oil leak in the nose area, not a fuel leak?
Roy

Thanks Cyrk,
I was wondering the same thing Roy was.

Ldub

Correct. Nose leak, fuel was fine.

or 10:1 rising rate fuel presure regulator. It's a handy little tool for leveling out fuel managment for low boost aplications. a worth while upgrade if your supercharged to keep fuel delivery smooth.

http://www.capa.com.au/vortech_fuel.htm

You got a good deal if he gave it to you for 200.

Well just got back from the dyno... 10:1 FMU is WAY overkill... It is pegged rich, We could not adjust it to lean it out at all. The shop thinks I am losing about 25HP from that, going to a 2:1 FMU or no FMU, will Dyno again after I get the new FMU or remove it.

Dyno'd 202.03... down from my last dyno 216.21, still hope my duals make a difference on the dyno after the FMU problem is solved.

The joys of modding your car.

Oh yea Tone the 2 guys that do the tuning at the dyno shop, race vipers and said to me. We saw a black one like yours at Porsche event in Corpus Christi, TX a while ago racing it was pretty bad Azz... LOL That was you no?

-Dave

coludve been me, mine is black and i live in corpus. that would be cool, ive always wanted to be spotted :)

Yeah, that was me! A lot of Porsche and Viper owners know me from the event down there @ Cabanis Field - those were some of the best times going down there and driving as fast as I wanted with Vipers screaming past me on the back straight and then me catching them in the twisties when they couldn't keep their power to the ground. And it only cost $20!

I stongly encourage any of you serious drivers to check with your local Porsche club as they offer these high speed driver's ed events almost monthly, provide a driving instructor until you are comfortable, and you are covered by your insurance should something happen - the events are held away from trees and curbs and I have never seen anyone crash out at the many events I have entered.

Ha Cool Tone small world!

New Dyno app set up for Tues. Taking the day off to get to the stores early to get and Xbox360 them make my way up to the dyno and mess more with the FMU, going to disconnect the vacuum line to negate the FMU to get a base run and go from there.

Well I did not score an Xbox360 (anyone got one they want to sell me?)... but I did get to the dyno today... we disconnected the vacuum line and that got rid of the FMU and the air/fuel curve was fixed. Gained a whopping 4.87hp over the PowerVault Generation one cartback but I lost 2.31TQ. :rolleyes:

Not too happy it was allot of money and time for under 5hp and it is still too loud (in my opinion). Got an app with exhaust shop the dyno place recommends here in the ATL, going to see if this duals are flowing right and if we can quite it down any.

here is the new dyno scan... almost done with modding the CrapaCROSS it is getting frustrating.

http://www.vehicross.info/gallery/da...s/New_Dyno.jpg