cardana24

iTrader: (81)

I am wondering if this has been done while on the stock ecu. My set up is: V2 on 3.125 pulley, AEM FPR, 370's, Vortech FMU 4:1 disc, SAFCII, Stock ecu, stock US manifold, and stock MAF. This is all on a 98 GXE. I ask this because I was at the dyno over the weekend and while I am still running a little rich I got my air/fuel a lot more stable. The guy running the dyno (specalizes in mustangs) says that I should take my FMU out and I would make more power, and I would still be able to run safe....does anyone have any experience with this? Thanks.
-Carson

--also could someone please comment on what my base fuel pressure should be with this setup. Right now I am right at 24-25 psi.

*edit* my boost gauge is not working properly so I do not know how many pounds I am hitting right now. On the dyno I put down 284 hp, and 265 ft./lbs with a fairly steady air/fuel ratio of 11:1.

michaelnyden

iTrader: (15)

bump bump bump bump

Stephen Max

iTrader: (59)

If you go to RC Engineering's website and play around with their injector size calculator, you'll find that you are in the ballpark for running without an fmu, but you are pretty close to the limit, depending on what BSFC you enter. Keep in mind that you are making about 340 hp at the crank (if you have a 5-speed tranny) so your air flow is very close to the upper limit of what the A32 maf is able to meter. This means that your injectors are probably running at about 100% duty cycle and you will not be able to richen your afr with the SAFC if it turns out that removing the fmu results in high end leanness.

I suggest getting rid of the fmu and going with either the Vortech super fmu or the Cartech fmu, both of which have an adjustable rise rate. The Cartech fmu also has an adjustment for setting the manifold pressure (either negative or positive) at which the rise begins. I can't remember if the sfmu has that feature or not.

cardana24

iTrader: (81)

what about just getting rid of the FMU with my current set up...the AEM FPR, and the SAFCII....would that not work. Right now I am pulling (with my SAFCII) anywhere from 24% to 40% (fuel) in between 3K and 6400.

Stephen Max

iTrader: (59)

You're pulling fuel because the 4:1 rise from the fmu is too much. Like I said earlier, you may be okay without the fmu, but it's going to be borderline. You'll just have to remove it and find out. The problem is that you won't be able to use the SAFC to add fuel at high rpm (if you need to) because your injectors are most likely maxed out (or close to it). So the only option available to lower your afr if you are running lean at high rpm is to raise fuel pressure. (Well, you could have your ecu programmed for a Z32 maf.) A sfmu or Cartech will allow more tuneability than just the simple disk type Vortech fmu.