Mazda Rotary 13B Swap in a Boxster

[tahleel]

I've been looking into building a nice weekend car. I've seen many Boxster's for sale, with engines with "internal damage." Seeing that this might be a common trend, I'd rather stay away from replacing the engine with another (costly) Boxster engine, only to have it fail with something that is unrepairable, or too costly to fix.

I plan on using a 13B engine (from a FC model), with a Kennedy adapter plate. The plate was made for VW tranny's, and I was wondering if it would work on the Boxster tranny. Does the Boxster have the same bell-housing pattern as the VW transaxles or the 911 transaxle? From what I've been told, the 911 transaxle can be used with the Kennedy adapter plate as well.

Besides that everything else should be cake. From what I've seen, the 13B has two side mounts, which shouldn't be too hard to fabricate. I'll be using the original Boxster tranny, so I wouldn't have to make any trans mounts.

As far as an engine computer, I'd run a standalone such as Megasquirt. It's been tested and works great with projects like this. The speedo and odometer should work, as I'm using the Boxster transaxle. The fuel guage should work, as I plan on using the stock fuel tank with an upgraded fuel pump. The coolant temperatue may work, depending on the proble placement, and sensor output. The oil pressure would not work, but who needs oil pressure anyways? :-D

And lastly, I'm not sure which years have the drive-by-wire. If it does come to that, I may be able to modify the stock pedals, and run the throttle cable into the engine bay. As far as the rest of the chassis wiring, it should remain the same.

I'd also like to retain A/C and powersteering. I will see if I can use the Boxster A/C and powersteering on the 13B via adapter plates.

I don't have the car, nor the engine yet, just the idea and plans. Any donations will be welcome. Advice, set-backs, etc is welcome and encouraged.

-Tahleel

Why a rotary engine? What advantages do they have over normal engines? If I had to swap a different engine into a boxster, It would be a 911 motor. And wouldnt the rotary have less HP, or will you have to twin turbo it?

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.

[vipola]

Originally Posted by tahleel

The oil pressure would not work, but who needs oil pressure anyways? :-D

Just to let you know, the oil pressure is something really important with rotary engine, if you don't care about it will probably cost you an engine just like my best buddy. Because a rotary engine got a OMP (Oil metering pump), and if you don't have the right pressure it will all be screwed up

but it's a very nice project!!

[CJ_Boxster]

Also a Rotory will likely raise your center of gavity... and You'll have to change the name of it from Boxster to Rotster

[porsche986spyder]

I'm not sure what kind of engine the 13B is, but the last model of RX-8 that was introduced had major problems with the engines. There was a complete recall for certain year models. I was looking at them before I bought my box and found an article saying that Mazda was going to have to bite the bullet and pay for it. Hope that isn't the same engine as the 13B?

Here is the article printed last Sept. 06
Engines failing vacuum test must be replaced

MONTEREY, Calif. -- After suffering a black eye from disclosing that it won't count RX-8 owners' opinions in its internal customer-satisfaction scores, Mazda says it may have to replace the engines in many of its flagship sports cars.

The voluntary recall of all 2004 and 2005 vehicles, and some 2006s, is expected to be announced this week or next. It involves damage to the catalyst resulting from oil leaks in the RX-8's rotary engine.

Any engine that does not pass a vacuum test must be replaced, said Robert Davis, head of product development and quality at Mazda North American Operations.

Engines prone to failing the test are mostly in hot climates and use synthetic oils.

Mazda also will check each RX-8's battery and starter, which tend to fail in cold climates.

"We're going to give these cars the white-glove treatment," Davis said. "We would rather replace the engine than have the dealer crack them open."

Davis would not disclose the projected failure rate of the engines or the cost to replace them.

Mazda has a remanufacturing center in North Carolina that will rebuild faulty engines and return them to service.

The recall comes after a video Webcast by two dealers who attended the July 11-13 National Dealer Advisory Council meetings in Newport Beach, Calif., was leaked on the Internet.

In the video, dealers said problems with the RX-8 were unfairly lowering Mazda customer-satisfaction scores.

Mazda informed the dealers that RX-8 owners would continue to be surveyed, but that the responses would not factor into dealer
customer-satisfaction scores. See story here

Mazda has issued service bulletins on such trouble spots as squeaky
brakes and engine flooding.

[JAAY]

I got an idea, since cost is an issue. Just buy and FD or and FC and keep the rotory motor in it. NO Fabrication needed.
Just my oppion.

[porsche986spyder]

Originally Posted by JAAY

I got an idea, since cost is an issue. Just buy and FD or and FC and keep the rotory motor in it. NO Fabrication needed.
Just my oppion.

What is a FD & FC????

[tahleel]

Originally Posted by JAAY

I got an idea, since cost is an issue. Just buy and FD or and FC and keep the rotory motor in it. NO Fabrication needed.
Just my oppion.

I've contemplated a FC, but they are just way too outdated. A FD would be a nice option, but they're severely overpriced in my book. Its actually cheaper and easier to find a low mileage Boxster over a high mileage FD. Although the initial cost would be cheaper, maintenance would kill me on the Porsche. :dance: And thats a price that I'll have to pay.

Plus, a Porsche is just drop-dead sexy.

-Tahleel