Guys,
In response to another thread about subarus, someone posted a link about a shop in AZ that is making an adapter plate kit to bolt up a boxster transmission to a Subaru motor.

Wondering if he sold a kit, or just did all the work, I reached out to him.

He does in fact sell a kit which requires milling out some of the bell housing, but then you can mount a starter.

Assuming much of the flywheel and clutch would not work, this might be a good place to start for someone who races, wants a more modern transmission, a cable shifter, and would like to remain all Porsche....

Naro...


Link to site for pricing etc.
http://www.boxsterengineconversion.com/par...ith-prices.html

Did you ask if it work with a Porsche 3.2 engine?

It's a flat plate of aluminum.
Holes need to be drilled for whatever motor you choose.

The hard part will be clutch and pressure plate, and flywheel.

It will work, yes, but the setup he sells is for a Subaru..
All the dimensions for the pressure plate offsets would be wrong..

Bet he could figure it out for you,,,,some really nice work on his site.

Rich

It will only work with a Subaru engine and uses stock style Boxster/Cayman clutches. If you wanted to use an air cooled Porsche engine, you would be on your own.

That is really not hard to do. I made my adapter plate for the Alien in my garage with a center punch and a hand drill. Many thousands of miles crossing the country is proof it works. Just takes some planning.

I bet KEP could do this quickly. He already has plates for the Trans, and plates for the Suby. Just some CNC programming?

This could be real interesting, but I wonder if it wouldn't be easier at the end of the day to just find a way to cram the Boxster motor in there WITH the trans that it's already mated to.

If you are mounting a Subaru motor to it, you're saving weight and with the right mods, getting (about) the same HP. The Subie trans when converted to 2WD is pretty solid, and there are a lot more/easier mods/parts for the setup.

I'm glad to see people engineering other ways around this, but I am still happy with the path I took on using the Subie motor/trans.

I don't think people are thrilled about boxter motors. At least the ones with the IMS issues. Blown motors at 60K is one reason boxters sell so cheap. I like the idea of putting a subie motor into a blown boxter but also think there would be interest to adapt a boxter trans to an aircooled 6 in a 914. It would give us another option to the typical 915 trans swap.

I agree fully with this part. It gets pretty tight back there though. The boxster trans is pretty big IIRC. If you had a 3.6 or something extreme in there, I can see needing the better trans.

The cable-shift alone makes the mod worthwhile if you ask me. Even sitting in my car, not running, shifting through the gears is tight and quick. I can't wait to get it on the road and see what it's like to have a 914 where I don't need to "hunt" for a gear.

That was kinda my point.
Subaru to Subaru is simple and well thought out.

Using a boxster transmission with the relocated start....well that was the first time I had seen anyone do more than just talk about the idea.

He went to the length of actually doing it.
Could someone copy him, maybe....but why bother.
He sells a kit....albeit it's just for a Subaru motor...

Taking his kit one more logical step to mate the boxster transmission to an aircooled porsche motor is a big plus and might sell even better.

For us, it may be a real and viable alternative to dumping money into an old 914 transmission that in the end still lacks a lot of the more modern things we expect.

Having a modern tranny solution is really interesting.

^^ Agreed
I have no interest in a Subaru motor. I want to keep it Porsche. There are A LOT of 914/6 conversions out there - I would suspect many more than Subie conversions. i would think if we could find a reliable, fairly simple way to mate up a Boxster trans to those, it would be a big win.

And this seems really close.
Boxster transmission
Starter relocate
Boxster clutch

Just need to setup a flywheel for your application, and drill different holes for your motor....which would be the same for any of the six cylinder motors...

Looking at the specs in PET and online, the Boxster and 964/993 clutch disks are teh same diameter. Both cars use a dual mass flywheel. But the Boxster uses a push type clutch, and the 964/993 uses a pull type.

I don't have any of them here, but I suspect the bolt pattern is the same for the pressure plate attachment. So IF you could bolt the Boxster pressure plate to the 964/993 flywheel, then there is no custom clutch parts needed. But you still need the adapter plate for the trans, and a place to mount the starter. The adapter plate may make the engagement of the pilot bearing a little short, and the throwout bearing stroke a little longer.

I would use the aftermarket racing flywheel to eliminate the dual mass setup, and use the aftermarket clutch throwout bearing that incorporates the slave cylinder into it. A spacer could be made the same thickness as the adapter plate for it.

Looks a little harder than that. From the picture thread and damn nice.
Click to view attachment
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I don't suppose someone has a CAD file of the 914 engine on Boxster trans bolt holes they would care to share?

I don't have a Boxster trans available and wanted to see if was feasible to redrill my Nissan adapter plate.

The pics above are from member "221kw914" - Alex.
I pm'ed him to see if he has a template.

Also, I emailed KEP. They manufacture an adapter for boxster to SBC & LS engines but not Suby or Porsche.

Ever get anything on this ?

Found this on Rennlist.



Nothing larger than a 228mm clutch will fit inside the 4 bolt pattern. The adapter plate above pretty much explains it. 1" Flywheel spacer to stock 240mm pieces. There are VW/Audi sprung discs to choose from. The Box/VW/A PP might bolt up to that 993 fly or be T/O bearing compatible.

As for me, I've got a built tall gear box and only 260hp so not really worth all the R&D time and cost. Hydraulic clutch should fix my only big issue. Maybe do cables as the rod is a tight fit around the oil pan.

I'm running an 11lb VW/Audi lightened flywheel with a SPEC Stage 3 clutch. It works with both my Boxster 5 & 6 speed trannys. I also run the cheap ($) VW slave cylinder instead of the expensive ($$$) Porsche unit that is exactly the same except the hydraulic fitting. 034 Motorsport sells fitting adapters with a plug and play -3AN end. It makes it easy to install with a Wilwood or Howe type master cylinder.

Here is a pic of a 901 and Boxster 5 speed with the axles lined up. The center line distance from the axle center to the edge of the bell housing is shorter on the Boxster. A 1" adapter would put the tranny in better alignment with the engine in stock location. With the axles lined up, the end of the tranny is in about the same place.

Click to view attachment

Do have any news about the 3.6L engine fitted to the Boxster trans?

I wanted to bring this back to the top and restart this discussion

Does anyone know how to get in touch with member ABC914? He hasn't been active for years. He's adapted the Boxster S transmission to 3.2 liter air cooled engine that I am looking for.

Here is his website http://www.abc-digital-art.com/. On the left side, below the Mail link there is a very small dot "." click on it for pictures. I have tried PM and email to him, nothing.

Bigkat - who's car is that with the 3.6?? And is that a Boxster S trans?

So...does anyone have any REAL WORLD experience with this that can direct me to how to do it?

I would REALLY like to do this during this winter if we can figure it out....

Thanks

Probably easier if I just show his pictures...

Here

Whois database.

thanks Rich
I contacted Alan and he told me who did the work on his car. Turns out, the guys in NJ that did the work I know very well - used to live about 3 miles from them. I'm going to give them a call this week, see if I can get some info on how to do this. Maybe they already make the adapter plates/kits?? That would be nice!!

I'll keep everyone posted on the progress...

Not sure, but I think they welded more material to the transmission case.

Well....I have news and bad news. (I won't say good news because its not really good)
the news is that I was able to contact Powertech - the guys that did the Boxster S trans conversion for Alan. I spoke to owner Keith Peare - long time 914 racer (now racing spec boxsters)

The bad news is..it was A LOT of work...like tons of work. Everything was custom, and they said they would NEVER do it again. The had to cut off much of the bell housing of the boxster trans, design a new adapter bolt pattern plate with hole for the starter and have it CNC fabricated, then welded back onto the trans, design in the hydraulic clutch system, fabricate the cradle/mounting system to hold the trans in place, etc. etc. etc.... (and more etc's...) nearly 200 hours worth of work that they only billed for less than half...

Plus, the Box S trans is MUCH heavier/bigger and sits back too far, so adjustments need to be made for that or you end up with a 911 weight distribution...

Hmm...not sure where to go now...

200 hrs? Having done this type of engineering in my back yard and pounding thousands of miles on my fabrication, sorry, Just not seeing it. I agree it's a challenge through. BTW: from those photos it looks like there is still a cut out section in the bell housing behind where the starter mounts. Doesn't look like the adaptor was welded to the bell housing at all. Maybe the photo is pre-completion.

ok, well I was guessing 200 hours...he said about $20,000 is what he should have charged. rates around here at least are 100/hr, so it was a guess. probably much less with the parts cost now that you mention it....but keep in mind, what you do for your own work is MUCH different than what a shop does for someone elses. They need to design, test and make damn sure everything is good on custom work before they let the customer have it or they will be spending months/years fixing little crap that kills their business.

My simplistic view doesn't see it as THAT hard to be honest, unless something major just doesn't line up: cut the bell housing, fabricate (CNC probably)an adapter plate to match up the bolt holes from the trans to the bolt holes on the engine. Fabricate the starter area into it/make sure it's spaced properly. Fabricate a transmission cradle, etc. The biggest issue I see is the hydraulic clutch system.

As Rich noted, the guys that make the adapter kit for the Suby engine/boxster trans - Precision Chassis Works - can provide a kit that might work. Having said that..their adapter kit is $2200, plus the clutch/pp, plus all the stuff to make a hydraulic clutch system, the shifter, cradle, etc. Will the axles fit (I assume the trans is not the same width as a 901), etc. etc etc...

so lets just say 100 hours of labor - still looking at $10k labor PLUS all the parts. I'm not sure I'm up for that...

I owned a collision/resto shop for 18 yrs. I understand the need to be sure things work and are done properly simply for liability sake if nothing else.

If the 20k included the transaxle, axles, hyd. clutch parts, shifter stuff and materials I guess you could drive that cost up there. Understood.

My assumption was you had the transaxle and wanted mated to your engine. That's actually the easy part in my opinion. Much of the project could be done by you to avoid a huge additional cost like axles and shift stuff. You know what they say about the word assume...

OK, so Alan sent me the invoice to do the work...holy crap..its a LOT more work than I thought. but some of the work I wouldn't have to do (like build a nice center console and figure out back-up lights) but yes, it was over $20,000 in labor alone.

Plus you need an electric speedometer that runs off of wheel sensors. Not hard, just more labor....and that's not even on this invoice...its on the NEXT one...

sorry, didn't mean to insinuate you don't do things right...that came across wrong, my bad. I just know custom work takes tons and tons of time, especially if you have nothing to go by and you're doing it for a client. I think if we are all honest with ourselves about the work we do, we would realize we spend much more actual time between research, trial, error, experimenting, installation, testing, etc than we would ever admit. For example, I've probably spent 50 hours just researching this already!! If I were a business, I would have to bill the client for it...

Labor did include trans tear down/rebuild plus a lot for the hydraulic clutch system design and install - lots of fabrication here especially for the pedal cluster which needed to be completely modified/redesigned. Seems that the output flanges on the trans are not compatible with the CV's, so more machining work. Labor list of things is almost a page itself...lots of stuff...

To be honest, not sure how much of this I could do myself. I don't weld, I don't have fabrication equipment, I don't have a good way to drop the engine/trans or a bench to work on all this. and i am certainly not tearing into the transmission. I can do a lot of basic replace/repair stuff, but not fabrication or heavy mechanical work.

So...looks like for now i might go with the Velios 915 that's been sitting in my garage for a year...maybe if the car runs well for a year or so I would start thinking of going the Boxster Trans route.

Stick with the 915 or get a g50
Tried and tested mid engine solutions for less money