Guest bastaad525 Posted November 16, 2004 Share Posted November 16, 2004 Well, I guess I'm an official guinea pig now. Cygnus - I decided to go ahead and give Trey over at B.E.G.I. a call right now, about this different spring and/or diaphram thing. I basically told him that in our application, the stock EFI easily provides enough fuel for boost up to a certain point, and that if there was a way we could get the FMU to come on later, at a higher boost level, but still provide the same final line pressure at full boost/wot, that that would work perfectly. So... he's going to start experimenting in the next week or so, he's going to make a few different sized diaphrams, and possibly get a softer spring or two, and send them to me FREE OF CHARGE, to try out in my FMU and see what happens. He thinks it shouldn't be a problem to get the thing to come on at a higher boost level, and hopefully be a big help with the super rich boost onset. My end of the bargain is that, as soon as I get my WB 02 (please santa??) I just give him all the details on how it works. I told him I think this would be great for ANY turbo setup that runs off of an AFM/MAF that directly measures air flow (which would all probably have the same problem of running too rich initially), as these types of setups compensate for increased boost and airflow quite well themselves, up to the limit of the fuel injectors... so there's probably a lot of interest there and good incentive for BEGI to explore this. Alternately, I may try to get an in-car fuel pressure gauge asap so I can start fiddling with these and seeing the results right away. Just thought I'd let you know, and I'll definately keep you updated on what happens with this. Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted November 17, 2004 Share Posted November 17, 2004 Nice work. Are you running for office? You got at least one vote! There is no reason an FMU cant be "fuel curved" mechanically just as a mechanical advance in a distributor can be. An electro-mechanical fuel injection system can be as good as a programmable if set up properly. It just wont be as flexible. Set it and forget it. Let me know if you need another opinion on the FMU parts. I may be able to get a few more Z driving days in before winter really sets in. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted November 18, 2004 Share Posted November 18, 2004 was actually thinking I might forward the parts along to you... depending on if I get my WB 02 or at least an in car pressure gauge or rather WHEN I get them. Because he can send me all the parts in the world and it does me no good if I can't somehow gauge how they are changing the FMU's behavior. You already at least have one way to 'test' it, running it off that air compressor of yours. So if I can't get something rigged very quickly, maybe I can just pass on the guinea pig mantle? Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted November 18, 2004 Share Posted November 18, 2004 Well yes, I can do the compressor test rig but I can only give an output fuel pressure vs boost. I am not sure how much value that has without reading WB02. Maybe we should split the cost of a WBO2. Shipping UPS ground from CA to NY may not be too bad. If you want to let's arrange via email. I will not be hogging the WBO2 much anyhow. You can use it first since it's still Z season there. Let me know. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted November 20, 2004 Share Posted November 20, 2004 Well you can split the cost with Santa a.k.a. my wife heheh though I'm not sure she IS going to get it for me. If she doesn't then yeah maybe we can work something out. Quote Link to comment Share on other sites More sharing options...
Guest Droopdude Posted November 20, 2004 Share Posted November 20, 2004 Take a look here: http://www.vems-group.org/wiki/index.php?page=HomePage Another FI project based off of MS. This one uses a wide band O2 for closed loop control at WOT and also can do boost control. Quote Link to comment Share on other sites More sharing options...
Tony D Posted November 22, 2004 Share Posted November 22, 2004 woah waitaminit here? are we calling things the same terminology here? Is this FMU some sort of electronic gizmo that manipulates the injectors, or is is simply a variable rate FPR (Fuel Pressure Regulator?) As you saw in my original post on this subject, a fixed rate FPR is all you need, jacking up the fuel pressure and solving for the new delivery rate to enter this into the MS unit. Tuning around a variable FPR would be actually simple if you know what maximum pressure you run at under full boost: simply do the calculation for terminal total flow from a single injector, enter it as the injector size in the Ms during setup, and compensate off boost by lowering the VE number to give less duration and fuel delivery accordingly... Fairly simple, actually, and would get you VERY close the FIRST TIME OUT instead of GUESSING (which is what many people call "tuning"). Some basic math beforehand makes for a lot less headaches and things that go "boom" afterwards... Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted November 23, 2004 Share Posted November 23, 2004 Tony D - Yep that's what it was... well I never USED to call them FMU's, rather I used their 'proper' name, RRFPR, but everyone else calls them FMU's (including the manufacturer) so it just stuck. But yes, the unit I'm talking about is an RRFPR, that supplies extra fuel pressure over stock, on boost only. Sorry for the miscomunication there. I've observed and tuned it a couple times at the dyno, the final fuel pressure under WOT/full boost is at 70psi, turning my 260 cc injectors into roughly 320cc injectors... so yeah the math is done, whenever MS gets in there tuning with the FMU shouldn't be too hard I would think and hope. I'm still amazed how close those few equations got me the first time I dyno tuned the RRFPR (almost called it an FMU again!). Though in retrospect, I did need to run a few more psi of fuel to support the end power at the wheels, than what the injector math predicted. Considering that those equations are accounting for power at the flywheel and doesn't take drivetrain losses into consideration (I always assume 15% loss), I wonder if that means the drivetrain sucks up more power than we think on a Z? Well... there's me thinking too deeply about stuff again Quote Link to comment Share on other sites More sharing options...
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