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Old 07-23-2007, 12:45 PM   #1
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I'm from the Ford camp and just bought a Miata to Auto-x. I have owned many 5.0 Mustangs that are Supercharged and was interested in your opinions on using a Mustang trick on a Miata.

All 5.0 From 87-93 used a MAF (like the vain meter) the Miata uses. They all come with 19lb ijectors. The basic school of thought from all after market suppliers of supercharger and turbo kits is use a FMU to up the fuel pressure to add fuel for the added air. The easer and better way is to elimate the FMU and just use larger injectors. I had 42lb injectors and made over 500 whp with no other changes. No chips, no tuners, no FMU.

This motor stock put down 200 whp and with just the application of larger injectors and backing down the timing it made 500+ with a safe A/F ratio. Question is...would this work on a Miata. Obliviously we would need a fuel pump to cover it but it will remain at the stock pressure.

Any thought?
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Old 07-23-2007, 01:28 PM   #2
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your mustang MAF is not like your miata AFM.

what a lot of had done is add an Rx7 afm as it's 30% larger...but it's not required even to run lager injectors. I was running 30 lb. (from 19lb) injectors with no other changes other than adjusting the idle-mixture screw on the OEM AFM.
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Old 07-23-2007, 01:31 PM   #3
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Quote:
Originally Posted by Braineack View Post
your mustang MAF is not like your miata AFM.

what a lot of had done is add an Rx7 afm as it's 30% larger...but it's not required even to run lager injectors. I was running 30 lb. (from 19lb) injectors with no other changes other than adjusting the idle-mixture screw on the OEM AFM.
My bad, I left out that you also had to change the MAF to one calibrated for the larger injectors.

So what your saying is you ran larger injectiors with no other changes and it did not run RICH?

The RX-7 AFM a plug in?
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Old 07-23-2007, 01:37 PM   #4
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Ok class lets review miata on 8 psi of boost 180-240whp. 5.0 on 8 psi of boost 300-500whp any questinons how many 1.6's/1.8's can we fit into 5.0 liters 3.125-2.777 times any questions. This is all covered very well in the faw however. FMU is pretty good i like it still but a real standalone map based system like MS, link, hydra is best. yes rx7 afm is PNP agian check the faq
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Old 07-23-2007, 03:02 PM   #5
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the AFM has an air idle-mixture adjustment screw...much like the idle-speed screw on the Throttle Body. Simple turn counter-clockwise, and the ECU can idle a larger injector.

It's then fueling in open loop where it poses a problem once you have too much boost pressure. You gotta find the equalibrium between the the size of the injector vs. the fuel pressure vs. the boost level.
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Old 07-23-2007, 04:04 PM   #6
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Quote:
Originally Posted by magnamx-5 View Post
Ok class lets review miata on 8 psi of boost 180-240whp. 5.0 on 8 psi of boost 300-500whp any questinons how many 1.6's/1.8's can we fit into 5.0 liters 3.125-2.777 times any questions. This is all covered very well in the faw however. FMU is pretty good i like it still but a real standalone map based system like MS, link, hydra is best. yes rx7 afm is PNP agian check the faq
Magna,

You have the most incoherent posts ever.

It hurts to read them.
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Old 07-23-2007, 04:28 PM   #7
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he knows.
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Old 07-24-2007, 12:05 AM   #8
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Quote:
Originally Posted by magnamx-5 View Post
Ok class lets review miata on 8 psi of boost 180-240whp. 5.0 on 8 psi of boost 300-500whp any questinons how many 1.6's/1.8's can we fit into 5.0 liters 3.125-2.777 times any questions. This is all covered very well in the faw however. FMU is pretty good i like it still but a real standalone map based system like MS, link, hydra is best. yes rx7 afm is PNP agian check the faq


Thanks for the math lesson

So I'm sure I'll be flamed for this...but where is the "FAQ" section. The only one I found is on the top of the page next to "User CP" and thats only for forum stuff:
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Old 07-24-2007, 04:49 AM   #9
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https://www.miataturbo.net/forums/showthread.php?t=4288
I had two fox bodies.
A 89 Hatch and a 91 Notch. Oh Boy Do I Miss My Muscle : /
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Old 07-24-2007, 05:18 AM   #10
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No you can't just blindly jack up the injector size and throw a bunch of boost at it. :/
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