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Old 03-11-2008, 01:45 PM   #1
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Default Vortech FMU totally wack?

So with a 12:1 disc in the thing, at stock 5 psi, it's asking for 110 psi of fuel, but the stock fuel pump will max at about 80 psi right? So does that mean that running the base greddy kit will blow out the pump? Or will the pump be ok running near its max, it just won't produce the 110 psi? I know you don't actually need 110 psi of fuel on 203cc injectors for 5 psi, so is the stock pump's 80 psi ok?

I would seem even with the base greddy kit at regular boost, it makes sense to use like an 8:1 disc which would still be asking for 90 psi which is still more than the pump can supply...

I'm installing the base kit for now and later yanking the Vortech and installing MS and big *** injectors to run stock fuel pressure, so I'm just curious about what to do for now while I'm running the greddy kit as it comes for the next 6 months or so...

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Old 03-11-2008, 03:35 PM   #2
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Without delving too far into the theory behind it, I think it's safe to say that the basic Greddy kit, as delivered, will work.

That said, I would not even dream of installing any turbo kit, regardless of what you're using for fuel management, without a wideband O2 sensor. You can get a complete AEM package (sensor, with gauge-type controller) for $245, shipped, here: https://www.miataturbo.net/forum/sho...243#post226243 You're going to need it anyway when you install the Megasquirt, so why not do it now and have some peace of mind?

The wideband EGO sensor is the single most valuable tool for tuning boost fuel that there is. If the sensor says that you're running lean, then you are running too much boost for your fuel system. If the sensor says you're running rich, then you can think about changing to a lighter disc in the FPR.
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Old 03-11-2008, 03:41 PM   #3
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it basically maxes the output of the pump and supplies enough...80psi is actually too much out of the box on stock injectors iirc.
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Old 03-11-2008, 04:19 PM   #4
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buy a walbro 190 and 8:1 recal disc and you should be fine for 5 lbs...but like joe said...a wideband is needed to show you if its safe enough to run your setup!!
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Old 03-12-2008, 02:38 AM   #5
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So the greddy kit runs rich at base psi basically... I guess that makes sense - it's safer at least. They don't have to worry about people complaining about blowing motors unless they alter the base kit in which case greddy can just say "you changed it we aren't responsible"...

Ooooook I'll send the paypal for the AEM wideband you linked to Joe... you talked me into it.

The only real downside to the wideband on a base kit is there is no ability to tune whatsoever - so if I'm running pig rich tough luck, I can't change it. I'm not planning on changing discs or doing any bandaid alterations since I'm just running the flat base greddy setup until I add the 550's and MS and then I can tune it perfectly...


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Old 03-12-2008, 02:47 AM   #6
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Getting the wideband motivates you to get a better fueling setup.
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Old 03-12-2008, 09:22 PM   #7
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It also lets you beat on your current system without worry that you're going to pop your motor.
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