RX7 drive train

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RX7 drive train

Postby rob66sprite » Thu Jul 02, 2009 11:45 am

I have been looking into different engines to use and am considering a complete 1987 RX7 drive train. Chopping the rear-end to fit would be out sourced but I am wondering what needs to be altered to get the engine and trannie in. Any engine or trannie I get from a private seller will be rebuilt. I would be buying the whole car and therefore have the needed electronics. Before I hear from you great people about staying original I want to remind you that I do not have an engine or trannie and would like to get 100-120 hp. I hope to keep the vast majority of the car stock but the power house is being considered for replacement. I have found some pics and stories about this sort of transplant but am looking for details or "watch out's". I am currently looking for the pro's and con's. Other ideas are always welcome. :D
Rob
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Re: RX7 drive train

Postby hpmowog » Thu Jul 02, 2009 12:18 pm

I don't have any direct personal experience with a rotary transplant, but I have seen several that have been done. A couple of points/observations:

1. You're going to need lots of radiator capacity compared to a Sprite, and will also need a large oil cooler.
2. The exhaust is rather large and hot. The exhaust ports are on the passenger side of the engine. One of the conversions I saw had a significant portion of the passenger footwell taken up by exhaust, containment, and insulation.
3. You'll need to source the remote control housing from a Mazda pickup transmission of the same era. B2000 or B2200, I think. The RX7 tranny has the shifter too far to the rear.

I like rotaries. However, my preference would be for a Toyota 4AGE. If your heart's set on a rotary, I know where you can get a nice street-ported 12A complete with carburetor and manifold for a really cheap price. Probably about 180 hp.
Karl Keiger
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Re: RX7 drive train

Postby admin » Thu Jul 02, 2009 4:39 pm

Passenger side routed exhaust isn't a problem, is it? :lol:
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Re: RX7 drive train

Postby rob66sprite » Thu Jul 02, 2009 6:01 pm

Thanks Karl,
Those are the bits I need to look into. I did not realize the shifter was so far back and was happy to think I had a "one stop shop" for the whole thing. Any idea at what HP I will need to start re-inforcing the frame. I really don't want to go that far, just far enough. You mentioned the 180hp 12A and that sounds like it would need frame support.
I really don't have my heart set on any particular style of engine and thats why I have been asking about different makes. I kinda wish it came with an engine so I would not have to choose between so many good options. :D I will be on a road trip soon and found a '66 1098 and a smooth case trannie that will be at one of my stops but they dont go together, do they? The problem I keep seeing with original transmissions is first gear and no fifth gear. After I spend enough money to ugrade I could have gotten something all together different. :?
Rob
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Re: RX7 drive train

Postby admin » Sat Jul 04, 2009 10:03 am

Watch the half-shafts on the original Spridget axle. They're weak spots, and upping the ponies will put them at risk. Racers typically go with double-bearing hubs and hardened (nitrided) half-shafts (which gets expensive). The hard-core engine swappers have also put in alternative rear ends.

Just something to consider....
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Re: RX7 drive train

Postby HAN5L778 » Sat Jul 04, 2009 11:05 am

The RX7 solid rear axle can be swapped in the Sprite chassis. I have seen photos in the photo section here of this swap. For a 100-120 hp engine you should be able to use the Sprite axle, but go with late model Midget axle shafts, BTA 806. If you find some old competition axles it's even better. If you go with double bearing hubs you will lose the hand brake as the bars for them will interfer with the hubs. The cost of modifying the RX7 axle probably won't cost much more than going to double bearing hubs and competiton axles.
Rick
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Re: RX7 drive train

Postby rob66sprite » Wed Jul 08, 2009 11:31 pm

I may have to leave this forum for a while. I was talking with a guy to buy an RX7 and was looking forward to putting it in when I found a ribcase and a complete 1098 for $550. I was starting to get nervous about starting a big conversion with this being my first Sprite and first full rebuild. I thought I would get into it and not finish after hitting a bunch of hurdles. The last thing I want is an almost finished car collecting dust. I have already heard talk about a 62 Sprite sitting in a field with the owner looking for some bids to come get it out of her yard. Perhaps I can put it in my yard and build it big after I finish the 66. :D
I thank all of you for your input and support and look forward to talking to you in the other forums!
Rob
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Re: RX7 drive train

Postby admin » Thu Jul 09, 2009 11:17 am

No problem at all Rob...happy to help give advice. That's the beauty of Sprites--so many choices, and it all really depends on what you want to do with your car!

:)
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