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Old 06-14-2007, 11:03 PM   #1
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Mazda Rotary 13B Swap in a Boxster

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

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Old 06-15-2007, 12:00 AM   #2
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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?
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Old 06-15-2007, 12:08 AM   #3
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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.
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Old 06-15-2007, 01:42 AM   #4
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Gosh why stop there... just go ahead and shoehorn a Chevy LS1 in there...
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Old 06-15-2007, 04:12 AM   #5
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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.
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Old 06-15-2007, 06:57 AM   #6
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LS2 is even better! With a blower too!
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Old 06-15-2007, 07:45 AM   #7
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Ive read articles about using the Subaru boxer motor. This should work.
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Old 06-15-2007, 10:06 AM   #8
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Quote:
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!!
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Old 06-15-2007, 10:13 AM   #9
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Also a Rotory will likely raise your center of gavity... and You'll have to change the name of it from Boxster to Rotster
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Old 06-15-2007, 11:34 AM   #10
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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.

Last edited by porsche986spyder; 06-15-2007 at 11:40 AM.
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Old 06-15-2007, 11:57 AM   #11
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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.
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Old 06-15-2007, 12:21 PM   #12
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Quote:
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????
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Old 06-16-2007, 05:35 AM   #14
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FD - Is the newer body style RX-7 the twin turbo not the new pos
FC - The older body style like the Turbo 2
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Old 06-16-2007, 08:09 AM   #15
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Quote:
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?


Quote:
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
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Old 06-16-2007, 08:12 AM   #16
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Quote:
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. And thats a price that I'll have to pay.

Plus, a Porsche is just drop-dead sexy.

-Tahleel
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Old 06-17-2007, 04:07 AM   #17
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The RX-8 is a fantastic car. I spent the last couple years driving around the country in one for SCCA Solo competition. It never gave us a bit of trouble on the road. The owner had a problem with the coil packs early in the car's life - fixed under warranty. But otherwise, we hammered the ******************** out of that car for two plus years and it never stopped ticking.

Nevermind that it has a stiffer chassis and a far more advanced suspension than the Boxster.

... that said, the rotary, to me, is not a good "fit" for the boxster
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Old 06-17-2007, 08:37 AM   #18
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Nevermind that it has a stiffer chassis and a far more advanced suspension than the Boxster.
Ya... Its not hard to have a stiffer chassis when you have a roof
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Old 06-18-2007, 10:19 AM   #19
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before I purchased my boxster i also was looking at getting a rx-7, 255hp in such a light car they really move but... they all seem to have cooling issues and the rotary engines as nice as they are drink gas like theres no tommorow. It also seemed when I was looking for one that even low mileage ones had already had rebuilds again as mentioned eariler apex seals crack due to over heating usually (very unreliable vehicles). If you are going to go through with doing this i would recomend you thow in an extra rad and if you are going for the twinturbo cooling will be even more of an issue.

even with all these concerns I would love to see this swap done the rotaries love the revs and sound soo nice (not to say the boxster dosent) but that would deffinatly be one unique porsche
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Old 06-18-2007, 10:38 AM   #20
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Main problem with the 3rd gen (FD3) is that the owners don't take care of the cars properly. They require frequent fuel filter changes and it's a very lengthy procedure to complete - so most skip it and the engines run lean and blow as a result. The cooling systems are also marginal and again, if they're not kept up it's bad news. Rotaries are not tolerant of overheating.

A few simple modifications to the FD platform, plus some common sense with regard to maintenance, yields a very reliable car. But most people just assume they're unreliable and stay away.

Yes, the fuel mileage does suck. No way around that.

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