Real Talk: Rotary Swap

[simontibbett]

All the BS aside of the people who say it's insanely hard, anyone ever really tried it? I was talking about it the other night and had researched it a while back, but haven't actually took my motor out and mocked a 13B in there.

HAS ANYONE REALLY attempted it or know someone personally who has? Everyone seems to think this swap cost over 10k, I am speaking 13B, carbed, THAT'S IT, no boost, nothing else. Stock Miata tranny. I hear you can use them, I don't know how. Depending on mounting do you HAVE to cut the firewall and tranny tunnel? Do you HAVE to do this and that that this guy says you HAVE to do www.rotarymiata.com.

I think they just don't want rotary Miatas so common so came up with a special club to scare people away lol.

Long story short, 1.6 is no good, rotary I can get for as much as McDonalds, could be fun.

If you DON'T have real experience with this swap, then I don't need to hear it's 10k, it's impossible, it's a lot of work, etc.

[Jack-MX5ATLanta.com]

Tyler picked up a 13B with the intention of carbs like you. I think you use the tranny from the rx7 but use the rear end of the Miata. The only major fabrication from what I heard are the motor mounts. It doesn't seem too hard to be honest but then again you'ld expect more if that was the case.

[wildfire0310]

Stock Miata tranny. I hear you can use them, I don't know how.
I think they just don't want rotary Miatas so common so came up with a special club to scare people away lol.

Ok so I am going to be really nice to your right now. Since I done something really really close

You can use a stock miata tranmission or the stock rx7. Either one, The biggest difference when all said and done with be how new the tranmission is and the 5th gear. 1-3 are close enough between the two tranmission not to matter and 4 gear is the same 1:1 ratio.

Ok here is how it work.

rx7 FC3s N/A tanny and Miata 5sp are both M-type and the core gear box is interchangeable. The difference comes(other then the gear ratios) is that the bell housing and tailshafts are different.

Now you can swap the bell housing and tail housing round with little work(most of the work is putting the miata tail housing on the rx7 gear box as there is a nice counter weight. Which either has to be removed or shave down the inside of the tail housing(which is what I did)

Now the biggest issue. I talked to a guy at MazCare when I did my swap and he said he had done Miata gearbox in an Rx-7 and said something about having to use the rx7 input shaft due to lenght. I want to say the miata one was to long(but i can't remember to T since it didn't effect me).

So if you wanted to use a Miata tranny with a rotory you would need.

Rx7 motor
Rx7 flywheel
Rx7 clutch
Rx7 bellhousing
Rx7 throwbearing
Rx7 pivot
Rx7 Slave(not 100% on this one)
Miata tranny
Maybe the input shaft from the rx7 the miata tranny.


Before any one ask:

---I am running an rx7 hybrid tranny in my miata now and have for about 5-10K miles with no real issue. Hence how I know all about this

---NO YOU CAN NOT USE AN R-TYPE TRANSMISSION to make a hybrid

Hopefully that helps

[metalman]

rotary I can get for as much as McDonalds,

That fact alone should tell you something. :lol:

[simontibbett]

Ok thanks for the help! I will look more into it. I'd like to keep it simple.

As for the motor being cheap, I have friends who race rotaries and aren't scared to help people for the low low :) lol.

[Jack-MX5ATLanta.com]

I don't think the Apex seal problem is too bad with the NA one's either, it's just a matter of keeping the oil topped up which is fine for an enthusiast but not so good for the casual customer, which I suspect is where the bad rep came from.

[wildfire0310]

I don't think the Apex seal problem is too bad with the NA one's either, it's just a matter of keeping the oil topped up which is fine for an enthusiast but not so good for the casual customer, which I suspect is where the bad rep came from.

It depends on how old the motor is. I know after about 100K the apex start to go, grained it tends to one seal mildly.

But to add my 2cent... Why would go through all the work to put just an stock-ish N/A rotory in the car.

You can have the same power from just a 1.8 with basic bolt-on for much less work.

Not trying to say don't do it but atleast boost it or port the motor or something. IIRC the stock power for a FC3S S4 motor was 127 whp.

[Jack-MX5ATLanta.com]

I thought that when carb'd up you could get some decent power from them? Either way, it would be a good idea to rebuild the motor if you're serious about it. If you're gonna get it for cheap it's worth making sure it's in decent nick.

[simontibbett]

Well that would be a possibility down the road, but I just love the powerband, sound, look, etc lol of a rotary. My friends basically stock 13B with intake and exhaust, and a few free mods will pull car lengths from a 1.8.

He pre mixes everytime he fills up too lol.

[Jack-MX5ATLanta.com]

I feel you there. Although I'm in a bit of a love hate relationship with the sound.

[wildfire0310]

Trust me there are a few of us that are rotary nuts. Blame my buddy for owning two FC's and for me owning a DSM. I drove his cars as much as I drove mine own.

I will own an FC or FD one day.

I am just saying time/money for each you could do a simple 1.8 with a shaved head and I/H/E and keep up with most simple FC. Now boost or brigde-port the Rotary and talk about a mean evil little rotary.

[simontibbett]

True, time isn't a problem. If I can do this swap for around the same price as a regular 1.8 then I will do it. I have welder and tons of other tools. Plus like I said endless supply to anything rotary.

[Roadster]

You've already got the PNP, Thimon. A bit of boost on the 1.6 seems like a much more effective route than trying to cobble together a rotary, unless you're just wanting to tinker with something. It doesn't seem worth the trouble for something less reliable. I know they can make a lot of power per liter, but....unless it's a really ridiculous power gain, like a 5.0 or LS swap, I can't see the point in messing up the good things the Miata drivetrain has going for it.

It'd be cool to see it done, at any rate.

[metalman]

You've already got the PNP, Thimon. A bit of boost on the 1.6 seems like a much more effective route than trying to cobble together a rotary, unless you're just wanting to tinker with something. It doesn't seem worth the trouble for something less reliable. I know they can make a lot of power per liter, but....unless it's a really ridiculous power gain, like a 5.0 or LS swap, I can't see the point in messing up the good things the Miata drivetrain has going for it.

That pretty much sums it up. And, when coupled with costs/aggravations of swaps in general is why more of these are not done....and when done usually utilize something other then carbs and 'antique' technology. ;)

[Acesanugal]

You can't beat the smooth power delivery of an N/A 13b. You just can't. True, in stock form they don't make a whole lot of power. When new it was only 146bhp. The thing about it is that the swap would be a cool project and the outcome would probably be worth it. The perfect engine in the perfect chassis. How can you top that?

But don't take my word, I'm partial...