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I have been around MR-2's and Rx-7s my whole life. I love 4 rotors and from what I can tell they aren't tooo big. This would be sick if it could work. This is more of a discussion than of it actually happening. I just think it would be awesome to have the best of both worlds.
 

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If you did it longitudinal it could work but then you're looking at either stretching the chassis or cutting into the cabin. Transverse would cause axle / exhaust manifold / turbo interference issue's.

I actually though about doing a 13b (or even a turbo 12a) for the hell of it years ago and it would work longitudinally mounted with a transaxle and only require a new subframe and sheetmetal work in the trunk but could still most likely keep the engine in the bay (not protruding into the cabin) and keep the axles from the transaxle (if the right one was selected) close enough to the axle centerline of the wheels. The 12a being 20mm shorter will definitly fit and the extra 20mm of the 13b should fit but will probably be tight.

The extra rough 130mm of just the 20b over the 13b will require either cabin protrusion or wheel base entending to get it to fit. A 26b will be too without extensive cabin protrusion and / or chassis stretching and will probably be too long for transverse mounting even if there wasn't an issue with exhaust clearance and the right axle.
 

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Then there's the cost to get the parts to build a 26b............

Now there is the option to couple two 12a's or 13b's together (which I've seen one in person that was two 12a's coupled together). This "option" wouldn't be too expensive to do. The one that I saw was actually in a drag rail and talking to the guy (which wouldn't give out too much detail), he said that you could take 2 running engines and build the basic setup for a reasonable price if you can get a good price custom machine work. From what I can tell, he had a custom aluminum adapter that bolted the two engines together and obviouly had some type of coupler to link the two E-shafts together. It was quite interesting to say the least and according to him was making 800hp from a pair of 12a's
 

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MidnightBlueMR2 said:
You could move it a few inches to the drivers side and tuck the transmission under a bit, but you would have to install from underneath

Thats the normal way to install an engine in an MR2 anyways so thats not an issue. I'm not familiar enough with that trans though to know if there wouldn't be clearance issue's between the axle and the manifold. When I thought about doing it years ago, it was with using the E153 toyota trans since it has 3 mounts that would bolt right up since its the OEM trans.

Speaking of odd engine swaps, I've actually been toying around with the idea of swapping in a WRX engine just for the hell of it. After taking a few dimensions, it could fit without stretching or cabin protrusion ran longitudinally.
 

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a 13B is about 20" long, the maximim width you can use with the E153 trans is 21" so it leaves just enough room for a bellhousing adapter in there. you could use a different trans to fit a longer motor, but i doubt you'd be able to fit a 3 rotor in there.

and yes, the passenger side shaft would interfere with the exhaust, but the wankel is pretty much a dry sump motor, rotating it a few degrees to miss the shaft when making the adapter plate should not be a big deal at all.

there would be plenty of room left in the engine bay for a turbo or two. it would be a fun build.
 

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Im curious of the cost. Last time I saw, the crank alone for a 4 rotor engine was like 8 grand. Is this still the case? I would love to see one of these in an mr2. What a sick sound.
 

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My '93 FD had catastrophic engine failure @ a hair over 100k miles (in less than 6 years off the showroom floor). MY '94 Turbo has 250k on the odometer and I'm pretty sure it will get close to 300k with minimial problems.
Lol not sure what the best part of both worlds would be a 3s-GTE in an RX-7 that would be sick. :didi: Sorry coudln't help myself.
 

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SuperMR2 said:
My '93 FD had catastrophic engine failure @ a hair over 100k miles (in less than 6 years off the showroom floor). MY '94 Turbo has 250k on the odometer and I'm pretty sure it will get close to 300k with minimial problems.
Lol not sure what the best part of both worlds would be a 3s-GTE in an RX-7 that would be sick. :didi: Sorry coudln't help myself.

Many FD's loose engines in the 80K~110K milage range and many factors contibute to it with probably the most common contibution being clogged up fuel filters. Due to where they are at and the PITA that they are to change, they rarely if ever get changed thus leading to a lean-out of an engine that is already tuned somewhat on the edge (unlike Toyota's pig rich tuning).

What further adds to this issue is the fact that they are MAP (Speed Density) EMS's so as you do BPU's and such, they lean-out more and more just like all MAP based setups since it has no way to know that the MAF (Mass Flow Rate) changed.

If an FD has a programmable EMS and is tuned properly with BPU's and or porting, they can be very reliable. Example, my FD was at 147K miles when I sold it still on the original engine (sort of). It was the original engine except that I did tear it down when I first bought it with 22K miles and did a minor street port on it. It was however assembled with stock OEM Mazda parts (no 3mm apex seals or anything, still the stock 3pc seals that were removed but new side seals and corner seals and all new springs for all locations).
 

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Turbomits95 said:
How much room is there from the axle line to the forward firewall/frame?
between 26 and 32" depending on how high you measure. the firewall slopes back.

axles can be swept forward slightly without issue, if you use a custom crossmember and ditch the trunk you can get more space.

with a setup like this you can get enough space for a 4 rotor:
 
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