Rx7 engine in an MGB? ((rx-b??))
 

I was planning on putting a 12a, tranny and rear in a 70's Mgb. Anyone out there done this? I don't think the motor and tranny will be too tough but it looks like there is a lot of work in the rear. I'm up in the air right now on weather or not I'm going to go ahead with the build or keep the rx7 and start over.

Hello, that sure seems like an interesting swap. I am not sure why you say the rear will be difficult? I would imagine a custom driveshaft is in order and would make that an easy part of the swap.

Either way you go, you win. If you keep the Rx as is, all is good. If you do the swap you have something very unique.

Good luck and keep us posted

Rich

Seems to me there is a build thread that I came across that has done just what you are talking about . you might want to do some reading through the threads and maybe find it . sometimes it can be overwhelming doing searches just keep the wording simple and straight . might find something in the old school and other category. good luck anything can be done it just takes time .:)

I did come across one thread that a 12a was put in a mgb. I believe he put the tranny and motor but I don't think he used the rear. I know having a custom driveshaft made would be the easiest but I was thinking I wanted to use the rx7 rear end. The mgb has leaf springs and it would be nice to have something a little more modern. Also, the Rx's rear is about 12" wider. I added some fender flares in the rear, about 6" on each side so the extra foot would work well. I do have a lot of work I want to do first, I really want to street port the motor. This is entirely uncharted territory for me, it may take a while. The rx7 really is in very good condition. I purchased it for 300$, the motor only has 10k on it, I could go on and on. Thanks for the tips.

Tony
Brooklyn park, mn

Hi, I've seen this done in person a few times. Just saw another one at Kurt Robinson's place a few weeks back. Kurt Robinson Enterprises, Mollalla, Oregon, just outside Portland, Oregon. Kurt is the local "go-to rotary guy". Kurt was just checking the cooling system after cleaning out the radiator & fiddling with the thermo switch for the fan set up, if I remember correctly. He said it drove really well, and this was with an automatic transmission!. All that I have seen use the stock MGB rear end, which is very strong & will hold up under the rotary motor with ease. Torque is what wears diffs & trannies, and I would think that the torque is higher with a B series MG engine. Just have a driveshaft configured & you're good to go, and it will look like a stock MGB. Tons of room in the engine compartment, and the rotary is quite a bit smaller & lighter than a cast iron MG lump.

Bruce

https://www.rx7club.com/old-school-o...b-pics-851180/
MGB with Mazda Rotary
Brian Kraus's 1976 MG Midget with 1986 Mazda 13B rotary engine

I am really interested in seeing this get done. I truly understand trying to update to a more modern rear suspension arrangement, but unless you have terrific fabricating skills, I think the custom drive shaft to the og mgb rear will save lots of headaches.

The width of the mazda may be able to be shortened in the half shafts, but that is one of many custom steps. The mgb rear will not pop with the rotary powering it. If you must change out the rear, please post pix, as it really sound interesting.

Good luck

Rich

There were mg's that came with v8's in fact one came with a 6. I believe the 8 used the same rear as the 4 cylinder. I don't believe it made huge power, I think it was a 215 or something, so it should stand up. No, I do not have amazing fabricating skills, that is why I was second guessing doing the rear. I can mig weld, all self taught. I am in Mexico right now, honeymoon. I have a week off of work when I get back and hope to have the motor out of the rx and taken apart. Another thing, like I said before, I have zero experience with rotary motors. This motor has 10k on it and I'm debating porting it. Does it really make that big of a difference? I read you can add 20+ hp by doing so but I know people like to stretch? Any help would be great.

Thanks
Tony
Brooklyn park mn
Via Riviera Maya

Tony haven't you got something better to do on your honeymoon than mail the RX7 forum :scratch:

Yea porting can make a fair difference but if you are new to the rotary maybe you should consider getting everything installed and working proper then after you have a bit more experience with the little engine do some work to it same with the diff it won;t be much more work to do a swap a little down the road.
Just a thought but if the little mg was mine I would want to keep it a stock looking as possible . Good Luck

Prather Racing family did pretty well with theirs........
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