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3x00 miata pondering

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  • 3x00 miata pondering

    So I have a wrecked 2000 Mazda Miata. I have a drivetrain in that Miata that is gutless and has a blown head gasket. My thought, and plan is to attend the 2018 grm challenge with a 60-degree V6 swapped Miata. The transplant would probably be done with a 3400 and a 5-speed transmission of unknown source. Any suggestions for the 5-speed? Also I would want to retain OBD2 compliant. In my state that means transferring over all the factory emissions equipment or at least making the computer read that it is all there. They don't do a visual they just do a hook up to the computer. That puts megasquirt out. My question for y'all is if anyone here has done this swap in a Miata, and just how well it turned out? Also what should I look to Source my trans out of? I've been out of the 60 degree V6 game a long time but I think I remember that the hot setup was the front wheel drive 3400 and an S10 2.2 5 speed transmission. But it's been a few years and a major head injury since I last played with these.

  • #2
    cant say ive seen a 3x00 miata swap before, im sure its been done though. you should be able to knock down a 3400 wiring harness down to the bare essentials and have it run happy in the miata with some tuning using hp tuners.

    as for a trans the s10 bellhousing is good as the starter pocket is on the correct side for the fwd engine, however the gear ratios are terrible (4.03 1st gear). if you use the 2.2l bellhousing with the ford transmission pattern you can run a 4th gen fbody v6 trans, the ratios are a little better although still not great. im going to be looking at the feasability of adapting a mustang t5 to a 60 degree for an upcoming project. i know it will bolt to the late s10 bellhousing, but the bearing retainer will need machining, itll need a custom pilot bushing, need to sort out a ford splined clutch disc, and im not yet sure if the input shaft length will work. the upside is the mustangs have the best ratios and are the most common.

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    • #3
      I wonder if i could make an adapter to the miata bellhousing for the 3400. Seems like those gears would be better than truck, and it would retain the stock torque arm.

      Will hp tuners be able to ignore the emissions equipment if i dont bring it over?

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      • #4
        anything is possible, it just takes some careful design to mate engines and transmissions that were never designed to go together. i have a chevy ecotec in a porsche 944, and the engine is mated to the factory porsche torque tube as the transaxle is in the back of the car like a corvette.

        you ill be able to shut off extra emissions stuff in the 3400 ecm, thats not an issue, however if you dont swap in things like the downstream o2 sensors, egr, evap, etc you will likely have problems passing the emissions test. when they plug in they are looking for there to be no trouble codes as well as all emissions monitors to be "ready", and usually they allow a max of one monitor thats not "ready". now if you eliminate the sensors, however you cant modify the programming for the emissions monitors, if you eliminate the downstream o2 sensors for example the ecm wont set codes for them not being there, but your monitors for o2 sensor heaters and catalyst will both remain "not ready", and you will fail your emissions test. this is al the fun of trying to make an engine swap emissions legal in an obd2 car.

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        • #5
          Ah. Ok. Never played with obd2 stuff. Honestly didn't know how all that works.

          As far as the adaptors go, i have access to a very good machinist and equipment through a friend of mine.

          3400 in rwd application: which side is the starter on? Miata is setup for passengers side. Im sure i can change it if need be, but....

          Obd2 looks for what in the pids as far as a late 90s 3400? That way i can do more research.

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          • #6
            I've done the those-aren't-supposed-to-go-together swap a couple different ways (with the same drivetrain).

            My first attempt used an adapter plate between the engine and trans, and it worked well, I just didn't get the patterns exactly lined up. I had to modifiy the bellhousing anyway, due to start location, so I figured for my next attempt I'd graft the 660 pattern directly onto the bellhousing of the trans, and this is what I'm using now. The trans is lined up much better and doesn't wear the pilot bushing prematurely.

            The picture of the engine on the stand is when I used the plate, the other picture is of the later modified trans.

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