VW W12 to Porsche G86.20 transaxle

[Joel Heinke]

Mounting a starter in place other than OEM can be done. For the Coyote engine in my Miura, the starter needed to be moved over to the other side of the engine to provide clearance for the transaxle.

An aftermarket, gear reduction starter commonly used for SBC was used. The bellhousing bolts were dual purposed to hold the starter by using longer bolts and a set of nuts on the long tails. An adapter plate was made on CNC mill and a bunch of aluminum carved off of the engine block to allow the starter gear to pass through to the flywheel/ring gear.

It took some time to work out how to do it, but in the end wasn't all that complicated. It feels a bit weird taking a die grinder and burr to the engine block but once the chips start flying it's just another custom bit to a custom car.

 

[Alexander M]

Thanks for the replies.

Measured up the W12 and designed the adapter this evening. The green 20mm thick plate mounts on the G86.20 transaxle, the blue 40mm thick plate mounts on the W12 engine. Does it make sense to mount a custom flywheel directly on the flexplate? If I use the flexplate as is - I have the starter issue sorted as well as the trigger wheel situation. Unfortunately I do have an additional length now of 20+40=60mm which is counterproductive to using the W12 in the first place.

If I remove the flexplate, the green flange is enough to connect the transaxle to the engine. But then I need to find a solution for the starter gear. What do you guys think?

 

[Alexander M]

Which transaxles could accept a 310-mm-diameter flywheel?

 

[Mesa]

Excellent reasoning!
Although the W12 is a different sound than a V12. Seems like the W12 "flywheel" adapter is only 40mm or about 1.6" not reallty a space killer when it comes to packaging. Or is it?

 

[Brian]

The flex of a flex plate is needed when you have a big soggy torque converter, but not what you want for a clutch.

Looks to me like you have the tools and knowledge to make an aluminum flywheel that you can mount the trigger and ring gear salvaged from your flex plate to on the front side and a clutch and pilot bearing on the back. I suggest aluminum because of weight (inertia) considering it's size.

 

[Alexander M]

Okay, found somebody that makes a flywheel for the W12 with a manual clutch:

ttvracing.com/product/audi-s8-w12-96-to-01e-gearbox-with-rs4-b7-clutch/

I hope they are willing to help me here. I would need a different version of that flywheel so that it can accept this clutch:

Clutch Masters 20-707-HDFF-R Clutch Kit 00-04 Porsche Boxster S 3.2L

<p>Clutch Masters 20-707-HDFF-R Clutch Kit 00-04 Porsche Boxster S 3.2L</p> <br> <h3>Features:</h3> <br> <ul> <li>Years: 00-04</li> <li>Best Street Strip</li> <li>Long Life (No Road Race or Autocross)</li> <li>Significant BreakIn Required</li> <li>OEM style disc Best with OEM...

www.importpartspro.com

Clutch Masters 20-707-HDFF-R Clutch Kit 00-04 Porsche Boxster S 3.2L

It reads "FX300" and apparently holds 110% over stock - which should be 480 lbf*ft. The W12 makes 430 lbf*ft. This should work.

There are more extreme clutches available:

Porsche SPEC Stage 3+ Clutch Kit Spec Clutch SPC.SP903FS SPC SP903FS SPCSP903FS | Pelican Parts

Spec Clutch SPEC Stage 3+ Clutch Kit Porsche 996&amp;amp&amp;semi;sol&amp;semi;Boxster S 2000 2004 $950.00. Call (310)626-8765. May Qualify For FREE SHIPPING. Parts# SPC SP903FS SPC.SP903FS SPCSP903FS. 911.

www.pelicanparts.com

SPEC writes " 671 lb-ft"

WDYT?

 

[Clive B]

Okay! Now I understand your point! The crankshaft was the most difficult thing to get right - due to its length and probably also the slightly reduced strength through the split pins? The early development engines had crank failures (fatigue failures). It shows you however, how thin and mass-efficient crank webs can be - if you come from the crude V8 world, you might think that these monster webs are "required" - but that is not the case. The crankshaft of a V8 is so "fat" and "overweight" that you can easily get away with cheap, cast material. I first noticed how beautiful cranks can be when looking at the Porsche Boxter engines, which also have really narrow web thicknesses. I investigated more and realized that the webs can indeed easily be half the thickness of the journal bearings... then came the W8/12/16 engines.

On the transaxle: there are a few kit-cars over here that put 1000hp through the W12/W8 Audi A8 transaxle. The Audi A8 came with the W12 engine and all-wheel drive - they made a transaxle for the W12 that resulted in the shortest engine/transaxle combo ever. You can see it below - its a fast-shifting automatic, electronically controlled (can use tip-tronik to manually advance gears on the steering wheel):

View attachment 128383

View attachment 128384

View attachment 128385

View attachment 128386

View attachment 128388

You can see that the differential is mounted basically "in the bellhousing" of the transaxle.

It is the shortest transaxle that exists. There was a guy here in Germany who used the W12 and the Auti A8 transaxle for Lambo Murci replicas and he pushed them close to 1000hp. He claimed "faster, significantly cheaper and way more reliable than anything Lambo" but he only made 8x cars or so of them before VW shut him down with law suits on copyright (VW bought Lamborghini and they employ lots of totally useless lawyers to prevent awesome things from happening - sort of my primary reason not to purchase anything VW/Lambo new anymore). The chassis was more spaceous as he modified the rear firewall and the trans tunnel was munch smaller thanks to this engine/transaxle combo.

You can pick up a W12/transaxle combo for just a few grand...

The second picture is an 8HP55 from an Audi Quatro. Check out this thread:
Using Audi Quatro Transaxle (8HP55) with a V12 - Adaptors

 

[Keith]

I’m using a 4.2 with the G86.20 most of their bolt patterns match (no adapter needed)
TTV makes a 10 bolt flywheel for early 4.2 that may bolt to the W12. Then the boxster 6 speed should bolt right up to the W12.

 

[Keith]

Most late model Volkswagen, Porsche, Audi Auto Group engine/transmission bolt patters are very similar. I'm in the process of mating an early 4.2L Audi V8 (ABZ) to the Porsche Boxster S 6speed G86.20 transmission. The Audi and the Porsche bolt together, no adapter required so, I suspect the W12 will also bolt up to the G86.20 with no adapter required if a smaller diameter flywheel (ala TTV) is selected. Most abandon this combination when they discover the starter locations do not align.

On my project, the Audi starter is on the engine and requires a deep pocket in the bellhousing to clear the starter nose. At this mating location on the G86.20 there is no deep pocket only the rim of the bellhousing. A solution, would simply router the bellhousing to clear the starter nose. I'm concerned this would significantly weaken the bellhousing and lead to disaster. Another solution, adapt a nose-less starter and bellhousing spacer similar to Joel's Coyote engine combination on page 2. This likely would also require a spacer on the throw out bearing to pair the profile of the bellhousing spacer.

Good luck I'm hoping you can make this work!

 

[Thomas McDermott]

Most late model Volkswagen, Porsche, Audi Auto Group engine/transmission bolt patters are very similar. I'm in the process of mating an early 4.2L Audi V8 (ABZ) to the Porsche Boxster S 6speed G86.20 transmission. The Audi and the Porsche bolt together, no adapter required so, I suspect the W12 will also bolt up to the G86.20 with no adapter required if a smaller diameter flywheel (ala TTV) is selected. Most abandon this combination when they discover the starter locations do not align.

On my project, the Audi starter is on the engine and requires a deep pocket in the bellhousing to clear the starter nose. At this mating location on the G86.20 there is no deep pocket only the rim of the bellhousing. A solution, would simply router the bellhousing to clear the starter nose. I'm concerned this would significantly weaken the bellhousing and lead to disaster. Another solution, adapt a nose-less starter and bellhousing spacer similar to Joel's Coyote engine combination on page 2. This likely would also require a spacer on the throw out bearing to pair the profile of the bellhousing spacer.

Good luck I'm hoping you can make this work!

Curious about an update on this as I have a beautiful Cayman with a 3.4 boxer six that is making metal and I like the idea of the 4.2 Audi V8 as an alternative (to remove, rebuild and replace the original engine which will cost $20K). This swap makes sense as if you grafted another two cylinders on the 3.4 you would end up near a 4.2 while Porsche and Audi are sort of like family (unlike say a Chevrolet LS which is a common big power swap). I Really would prefer the Audi W12 or Bentley W12 TT even if it requires a lot of cutting and fabricating as Bentley is also family to Porsche/Audi and there is a 12K miles unit for sale for under $4K and in theory it should bolt up easily as stated earlier. I think this thread started with a guy that wanted to put a W12 in a Boxster and I'm interested in where he is at as a Cayman is essentially a hardtop Boxster. A high compression Audi W12 without the turbos should be smaller than the twin turbo from the Bentleys and might more easily fit. [email protected]

 

[Keith]

There is much swappablity between VAG (Volkswagen, Audi, Porsche, Bentley, Lamborghini) engines and transmissions just like there is between North America auto manufacturer's engines and transmissions. Unfortunately North American auto manufactures have never made longitudinal transaxles and European Auto manufacturers have never made cheap, reliable, powerful engines. Pity!

 

[Thomas McDermott]

There is much swappablity between VAG (Volkswagen, Audi, Porsche, Bentley, Lamborghini) engines and transmissions just like there is between North America auto manufacturer's engines and transmissions. Unfortunately North American auto manufactures have never made longitudinal transaxles and European Auto manufacturers have never made cheap, reliable, powerful engines. Pity!

There is much swappablity between VAG (Volkswagen, Audi, Porsche, Bentley, Lamborghini) engines and transmissions just like there is between North America auto manufacturer's engines and transmissions. Unfortunately North American auto manufactures have never made longitudinal transaxles and European Auto manufacturers have never made cheap, reliable, powerful engines. Pity!

"European Auto manufacturers have never made cheap, reliable, powerful engines." Go to eBay and look for a Bentley W12 Twin Turbo with 12K miles on it for $4K. That's cheap and reliable but what can it fit? As you and I both have Cayman/Boxster with sticks can you figure a way to cut the car and make it fit? A blown 3.4 Cayman S engine will cost you $4K. Seriously, what can accept that engine?

 

[Keith]

"European Auto manufacturers have never made cheap, reliable, powerful engines." Go to eBay and look for a Bentley W12 Twin Turbo with 12K miles on it for $4K. That's cheap and reliable but what can it fit? As you and I both have Cayman/Boxster with sticks can you figure a way to cut the car and make it fit? A blown 3.4 Cayman S engine will cost you $4K. Seriously, what can accept that engine?

Ok, you first!

 

[Keith]

Ok, you first!

Oh, and I have a 914, the poor man’s Porsche.

 

[Alexander M]

Attached to help the project moving forward.

What I need next: What is the distance between the flywheel clutch mounting surface and the flange mounting surface of the G86.20? Does anyone have this measurement? I asked KENNEDY ENGINEERED PRODUCTS, INC. - they have this measurement as they make an adapter to an LS engine, but they did not seem to want to help here.

The flywheel and starter motor and the trigger wheels can sit on the front - I can mount it on the harmonic damper. That is probably the easiest solution.

 

[Thomas McDermott]

I just sent an email to [email protected] asking them a slightly different question. It was whether they have an Audi/Bentley W12 adapter for anything as they don't list an 12 cylinder engines but many 4, 6 and 8 cylinder options. Alexander M, what did you plan to put this engine into, a GT40?

 

[Alexander M]

Look, these W12 engines are one of the most underrated engines ever made. There is no aftermarket for them, which is why they are very affordable. I want to put one into a Countach replica....

 

[Alexander M]

LS versus W12 in that Countach / Lorico frame

 

[Neil]

LS versus W12 in that Countach / Lorico frame

View attachment 138026

That chassis definitely needs a stressed panel across the bottom.

 

[Alexander M]

wh

That chassis definitely needs a stressed panel across the bottom.

What do you mean? Can you explain?

These chassis were road legal back in the 80ies in Germany... They were built by a company named "Lorico". I have the TUEV (traffic authority) documents here, they complain that the torsional stiffness in the rear is very low but that did not render the frame / car invalid and these passed all dynamics tests back in the day.