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dean1484 SuperDork
6/24/11 3:50 p.m.

Are there any motors (other than another rotary) that will bolt up to the trans in a FB RX7? Any other Mazda offerings. I know the logical way to go would be get a Miata motor and I guess that is an option but what about other options.

I will precises this by saying I would like t keep this to 4 cylinder motors. Maybe 6 if it was something really interesting.

This all started with me thinking about 4age's and there 7000 plus red line and how that would probably work very well with the drive line of a rotary powered car. I am also missing my 85 gsl as of late. So that led me to think hay why not see about putting the two together.

I would assume I Would have to swap over a T-50 with the 4age and just fab up a custom drive shaft but the T-50's are getting harder to find (at least for me). Any other options? Any other bigger more modern motors ( again, that are 4 cylinder).

Another thought was to look at the motors in the small Mazda pickups. I think they has a 3.0 V6 with a 5 speed. That would be interesting.

I am not looking for Huge power. I am also not looking at shoehorning a SBC or LSX in an FB. I like the idea of a 4 cylinder to keep service and maintenance costs down and millage up. If the need for more speed comes in I can always add boost.

Other things that have been pondered.

1.9 from a late 80's escort. Simple and basically a miata motor.

SHO motor (the Yamaha one) but again I don't know the transmission options. and I bet the fitment would be an issue.

Millenia S motor. 2.25L all aluminum. This is kind of a pipe dream but I researched these a while back and the engineering in them is phenomenal. I think I would have to go boosted with this option form the get go but. .. . . well. I would try to convert it to a turbo and a simple home brew intake. I have a turbo on the shelf from a Mazda 3 / cx 7 2.3l on the shelf.

4.0 V6 from an explorer

Anyway this is just want is rattling around in the space between my ears for the last couple days. Thought I would share and see what others can add to it. And of course enable me LOL

92CelicaHalfTrac SuperDork
6/24/11 4:03 p.m.

I'm pretty sure (someone may want to check me on this) that to use the Miata motor, you have to use a Miata front housing bolted onto the RX7 transmission.


Here's where it gets interesting.

I also believe you can bolt on the front case from a B2200. Yep, it's F2T or FE3 time!!!!!


That thread gives you an idea of what you'd be looking at. Doesn't seem all that bad for your average GRMer, actually.

Don't bother with the Millenia S motor. It's a Miller Cycle motor and needs to see positive pressure just to RUN. I don't think i've ever heard of anyone turbo'ing one, and i imagine that's why.

However, the 2.5 V6 in the base Millenia, that's another ball game, and would also be doable. There's a guy running SSM in a KLZE (2.5 v6) Miata, and that build is documented somewhere. Doing the same in an RX7 wouldn't be much different at all.

Conquest351 Reader
6/24/11 4:56 p.m.

The Miller Cycle Engine can be twin-charged I'd think.

I read about the opperation of that engine. Variable Stroke Engine. Uses the supercharger for pressure and the cam to hang the intake valve open longer while the piston comes back up for the compression stroke. It basically varies the stroke by letting the engine push back some of the intake charge and then finally closing the valve for the rest of the stroke.

It's friggin' weird.


92CelicaHalfTrac SuperDork
6/24/11 4:57 p.m.

^Yeah, twin-charging would work, but i don't see how just a turbo setup would work. It would either run like dog E36 M3, or not at all, until you saw boost.

At the end of the day, it's easier, cheaper, and will likely make more power if you just turbo the base millenia motor.

clutchsmoke Reader
6/24/11 5:24 p.m.

KA24DE out of a 240SX. Cheap, plentiful, and stout.

Curmudgeon SuperDork
6/24/11 8:13 p.m.

The RX7 bellhousing fits only rotaries. That means the various 12A and 13B variants along with a 20B should your budget stretch that far. But that should not limit your hunt! I personally like the idea of a 300ZX turbo or twin turbo sitting in a 1st gen body. Or, a supercharged 3800 from a Riviera or etc married to a Camarobird transmission. Want to use that super cool 3.0 SHO motor? Use a RWD bellhousing from a 3.0 V6 Ranger or Aerostar and then there's all kinds of plentiful transmission options. Naw, I've never thought about this.

About using a Miata motor on the RX7 transmission: the RX7 has a super low stump puller 1st gear for use in traffic. That's not suited to a Miata motor at all. So were you to do a Miata swap there is no real benefit to all the aggravation of swapping bellhousings between the two transmissions. I'd just park the Miata powerplant in the RX7 and use the RX7 tailshaft housing to make the rear mount simpler.

RexSeven SuperDork
6/24/11 8:32 p.m.

Granny's Speed Shop has engine mounts for the Nissan VG30 and Ford 2.3T, but only for the FC. If you can't fab them up yourself, maybe you can ask Granny's to make some that fit the SA/FB.

Nitroracer SuperDork
6/24/11 9:58 p.m.

I like the idea of a miata 1.6/1.8 in the early rx7 too. Still a fun rear wheel drive car, a bit more classic feel, and no soft top. Bet it would still be a hoot to drive and get great mileage.

Chas_H New Reader
6/24/11 10:09 p.m.

Get a Miata if you want a Miata engine. The soul of an RX7 ia a rotary engine.

aussiesmg SuperDork
6/24/11 10:44 p.m.

Hey Chas, it's a car, no soul included


America Berkeley Yeah

dean1484 SuperDork
6/25/11 8:03 a.m.

From the Wiki

The SHO engines share a common bell housing pattern with the following Ford engines: the 2.3/2.5 L FWD HSC I4, the 3.0 L FWD/RWD Vulcan V6, and the 3.8 L FWD Canadian Essex V6.[8]

This is seriously making me think. Red line limited to 7k Fuel cut at 7300 prototypes running to 8500 but had to be limited due to accessory failure. I can see this motor in my future. LOL Then there is the reversible intake making a RWD install all that more simple. 220-230 hp in stock form in a FB Ya I think I could live with this for a while LOL.

Curmudgeon SuperDork
6/25/11 12:22 p.m.

Out of curiosity, guys: is there any RWD variant bellhousing that will fit the V8 SHO block?

dean1484 SuperDork
6/25/11 1:23 p.m.

And to top if off I then go find this.


$400 for the whole car!!!!! Looks to be the perfect doner. Hummmmmm

I am in deep trouble.

Curmudgeon SuperDork
6/25/11 6:55 p.m.

Hee hee.

ShadowSix Reader
6/25/11 7:02 p.m.

I think you may have found a winner.

92CelicaHalfTrac SuperDork
6/25/11 9:22 p.m.

You can also swap the 3.0 V6 out of the 929 into an RX7 somewhat easily. The "JE-ZE" is a monster in itself, and is arguably just as strong if not stronger than the Yamahammer.

Nitroracer SuperDork
6/25/11 10:47 p.m.
Curmudgeon wrote: Out of curiosity, guys: is there any RWD variant bellhousing that will fit the V8 SHO block?

The SHO V8 is based upon the 2.5L Duratec V6, but I can't remember if any rwd transmissions bolt up to it.

92CelicaHalfTrac SuperDork
6/25/11 11:27 p.m.


(At least, i think?)

dean1484 SuperDork
6/26/11 8:19 a.m.

I have been spending a huge amount of time screwing around with a MS project in my 924s. All to add some boost hoping to get in the 225 hp range. Then this SHO motor pops up.

Getting completely of topic here but what type of ignition does the sho motor have does it use the same EDIS ignition that other fords of the era used?

psteav Reader
6/26/11 10:00 a.m.

It's been done, but the easiest swap for these is the SBF...and aluminum heads for the SBF are cheap and easy to come by. That'll take care of the weight issues. OTOH, it's been done. And done. And done.

Personally, I like the idea of an SHO V-8 if you could get it to bolt to a RWD trans. Problem would be finding an SHO with a good motor and bad body (because they all seem to be the other way 'round, thanks to the stupid swaged-on cam sprockets).

The SHO V-6 is really cool, too, but they are heavy and bulky....like iron-block V-8 heavy and bulky. Still would fit in an rx7 engine bay, though. Easy to come by cheap and easy to bolt a RWD transmission to, as well..

Lexus 1UZ would be pretty cool, and very compact for a DOHC V8. I think the adapter for the manual trans is pretty expensive, though.

Curmudgeon SuperDork
6/26/11 11:05 a.m.

I seriously considered a 1UZFE swap in the Jensenator (you never know, it could still happen) so I did some research. There's a kit out there to bolt a Toyota manual transmission to a stock automatic transmission bellhousing. The flywheel is separate, but somewhere out there on teh int3rw3bz is a tutorial on how to modify, IIRC, a Chevy? flywheel to work. There's also a sorta rare 3SGT-E flywheel that can be installed by slotting the flywheel bolt holes.

If you don't want to mess with doing all that, try these folks: http://www.monster-performance.com/modules/shop/product_info.php?products_id=29

Strike_Zero HalfDork
6/26/11 12:15 p.m.
dean1484 wrote: And to top if off I then go find this. http://providence.craigslist.org/cto/2381311620.html $400 for the whole car!!!!! Looks to be the perfect doner. Hummmmmm I am in deep trouble.

Buy it now!!

And I do believe that the SHO v6 uses EDIS . . .

dean1484 SuperDork
6/26/11 7:46 p.m.

Sent them a message but no reply. At $400 I can probably ebay off allot of it and end up with a free SHO motor. Orrrrrrrrrrrrr it could be challenge car material depending on the extent of the welding needed.

Another question: How do these SHO motors take to boost?

Nitroracer SuperDork
6/26/11 9:42 p.m.

Not sure how well they take boost, but here is a boosted example


RossD SuperDork
6/27/11 7:52 a.m.

Here's my standard argument: Zetec. They are cheap and there are hop up parts available. They mostly share the Pinto/Crossflow/CVH/Old Lima bolt pattern and could be bolted up to the newer Lima pattern (Fox body, Xr4ti...), IMHO, with a little mill work and a plate. It's a fairly common swap in Europe for getting a DOHC engine in an older rwd 4 cylinder car. Plus the Lotus community uses it a lot too as a cheap replacement to a hopped up xflow or Lotus Twin Cam.

By my internetting skills, 170 hp should be doable by getting a good header, some individual throttle bodies, and a good tune. When I weighed the one on my engine stand, it weighed about 250 lbs, IIRC. It had some brackets, coil and wires, automatic flywheel, water pump and some fluids, and was complete from the exhaust manifold to the throttle body.

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