Mazda Rotary 13B Swap in a Boxster

The orientation of the transaxle is different in the boxster vs. 911. The 911 is rear engine and the box is mid, so you'd have to rework the rotation of the engine I believe. That is what I heard for 911 transplants in boxsters anyways...

The 13b can make decent power with a bridgeport or street port ~250 hp. Turboing can net ~400 until you run into apex seal problems. Apex seals are the weak point on those motors. At least that was the case +15 yrs or so since I've toyed with them. Not sure if metallurgy has improved enough to run more power.

Dimensions for the bare blocks are similar in that both are wide and low. The difficulty I see will be getting all the ancillary components to fit, e.g. A/C, alt., power steering pump. You'll have to be a master at fabing brakets.

Having said all that, I don't know the value in a NA conversion. If you go turbo, with the added complexity, why not look into Buick Grand National power? That's the swap I'd like to make. 600 hp reliably on the bare block internals. Depends on how radical you want to go. If you want insane fast, and don't care about stock, then you have the whole trunk to work with for intercoolers and all. There's not much difference in pricing between 13b and GN, but gobs and gobs more torque and power.

Whichever you chose good luck and keep us posted.

[easyc]

Gosh why stop there... just go ahead and shoehorn a Chevy LS1 in there...

[John V]

I love rotaries, I've rebuilt two of them and owned an RX-7 turbo for a long time.

But I would never in a million years put one in a Boxster. The last thing I would want is that motor in a relatively inaccessible location. Now an LS1 - that I could be interested in.

[Brucelee]

LS2 is even better! With a blower too!

[986speedster]

Ive read articles about using the Subaru boxer motor. This should work.

[tahleel]

Originally Posted by boxsterz

The orientation of the transaxle is different in the boxster vs. 911. The 911 is rear engine and the box is mid, so you'd have to rework the rotation of the engine I believe. That is what I heard for 911 transplants in boxsters anyways....

This is pretty eye opening. I thought the 911 was a mid-engine car just like the Boxster. I've done some reasearch, and found that there's only two shops that can do the reverse rotation. And with high demand, there's going to be high cost. It seems a lot easier and cheaper to swap in a VW transaxle, and reversing the orientation of the spin yourself.

Now, will the VW Beetle transaxle bolt-in into the Boxster chassis?

Originally Posted by boxsterz

Dimensions for the bare blocks are similar in that both are wide and low. The difficulty I see will be getting all the ancillary components to fit, e.g. A/C, alt., power steering pump. You'll have to be a master at fabing brakets.

Having said all that, I don't know the value in a NA conversion. If you go turbo, with the added complexity, why not look into Buick Grand National power? That's the swap I'd like to make. 600 hp reliably on the bare block internals. Depends on how radical you want to go. If you want insane fast, and don't care about stock, then you have the whole trunk to work with for intercoolers and all. There's not much difference in pricing between 13b and GN, but gobs and gobs more torque and power.

As far as any other engine, the reason why I would choose the rotary would be that it is compact, and has "enough" power. A V-type engine has a different center of gravity than a Rotary, and thus changing the handling characteristics. Also, with a V-type engine, the extra height may not clear the engine bay .

-Tahleel

-Tahleel

[insite]

Originally Posted by tahleel

This is pretty eye opening. I thought the 911 was a mid-engine car just like the Boxster. I've done some reasearch, and found that there's only two shops that can do the reverse rotation. And with high demand, there's going to be high cost. It seems a lot easier and cheaper to swap in a VW transaxle, and reversing the orientation of the spin yourself.

the boxster and 911 engines spin in the same direction. the difference is in the transmission. the output shaft on a 911 transmission spins opposite that of a boxster. figure out which way the standard FC motor spins. if it's the same as the boxster / 996, then use a boxster tranny. if it's OPPOSITE a boxster / 996, use the 996 tranny. problem solved.

[tahleel]

Originally Posted by insite

the boxster and 911 engines spin in the same direction. the difference is in the transmission. the output shaft on a 911 transmission spins opposite that of a boxster. figure out which way the standard FC motor spins. if it's the same as the boxster / 996, then use a boxster tranny. if it's OPPOSITE a boxster / 996, use the 996 tranny. problem solved.

Using logic, I would use the Boxster tranny.

The 911 engine is rear engine (tranny pulling engine).
If you spin the tranny around to make it mid-engine, then the five (six?) foward gears, would be come reverse gears.
The 911 engine spins the same directions as the Boxster engine.
The 911 trans spins the opposite direction of the Boxster trans.
We need the opposite of the 911 trans (see line 1), thus needing the Boxster trans.

Even going furthur. I've read that the Boxster and 911's have similar blocks, leading to similar transmission bolt-pattern. If the Kennedy adapter plate works for the 911 transmission, it should work for the Boxster trans without a problem.

Can anyone find a fault in my logic?

-Tahleel

-Tahleel

[insite]

Originally Posted by tahleel

Can anyone find a fault in my logic?

-Tahleel

which way does a 13B spin? FYI, the bell housing on a boxster transmission is identical to that of a 996.

[tahleel]

Originally Posted by insite

which way does a 13B spin? FYI, the bell housing on a boxster transmission is identical to that of a 996.

I believe the 13B spins clockwise while looking at the flywheel. Spins counter-clockwise while looking at the pulley's.

As far as the bell housing bolt pattern, is there a difference between the watercooled and aircooled transaxles? I believe the Kennedy adapter was made for the the aircooled. I've been comparing pictures of Boxster vs 911 watercooled trans's, and they seemed different. Also, from what I remembered, it looks like the 911 has its started mounted by the rear of the trans, and has a shaft/tube running to the flywheel.

-Tahleel

[kouks]

Hey if you're going rotary lets not mess about with 13b or even 20b's. Go for the big daddy 4 rotor from the 787B. This car won the Lemans 24 hour in 1991 then was banned from racing...

http://www.youtube.com/watch?v=TgstvDmmVc0