I am really interested in this project because I am debating on a w12 swap into a C5 Allroad. I used to have a W12 A8L (2009) so I have an understanding to their complexity but I lived that motor. Any updates or further information you could share would be greatly appreciated.

 

Thread revival... only 8 years on and no, I haven't finished it. Sorry.

Many things have gotten in the way inc a Divorce and Custody proceedings for my two sons who are now 6 and 4.

Anyway.. back to the W12 info.

I've had an adaptor plate made to bolt the W12 to a Boxster S (986) 6 speed gearbox (same bolt up fitment as a 996 gearbox) but I'm still working on the flywheel.

I have found a couple of possible options for flywheel and clutch that I have found which are factory parts. I don't want to buy a one-off kit.

The issue has been that the W12 6.0 has 408 ftlbs of torque. Very few VAG vehicles (I'm concentrating on parts that will bolt together) have this much torque and are bolted to a manual gearbox.

1) Audi R8 V10 (413ftlbs) flywheel and clutch. This bolts up to the W12 crank and is a dual clutch disc setup.

The issue is making an input shaft adaptor/extension that will slip onto the Boxster S (986) input shaft and into the R8 V10 clutch. I have managed to get my hands on a second hand set and an input shaft from an R8 gearbox (not easy to find) and am now looking to have it modified to fit between the gearbox and engine.

.

2) Audi 3.0TDi V6 (368 ft lbs) flywheel and clutch. Again this bolts up to the W12 crank and has the spacer bell which helps with the 50mm depth of the adaptor plate.

.

MG

 

I've been looking into other gearbox choices and have realised that the R8 6 speed manual gearbox offers a possible bolt up solution.

The question is whether the bolt pattern on the R8 engine is similar enough to the W12 to make it work.

So... here's the ask!

I've grabbed a photo of the R8 BYH engine but I don't have the ability to overlay it onto the W12 engine. Please could someone do this and post it up here?

Here's the photo of the BYH.

MG

 

it sounds like you have picked the wrong engine to do an inexpensive swap!

Lol, probably.

I can use the standard manifolds and make up a fairly cheap system after that as a start point and upgrade later on.

MG

 

it sounds like you have picked the wrong engine to do an inexpensive swap!

 

I haven't tried tbh. I'm not that worried about the wiring at present. I know someone who can re-write the ECUs when I need to.

I did however find this photo...

I want these headers!!

I have been in touch with the manufacturer but they want almost £4,000 to make them!

I'll have to keep looking.

MG

 

have you tried getting in touch with the guy on volksforum doing the fridolin w12? he could probably give you pointers/ tips on what to do for the wiring

 

Almost positive you can use the SteveKen adapter kit for the trans. The wiring shouldn't be tough, the technology isn't that advanced for an 04ish car. Just use the W12 cluster and wire it up correctly.

It's Steve that I've been in touch with. I sent him detailed photos etc to help check that the W12 has the same bolt pattern. I just can't afford to buy the kit

MG

 

I have found someone who makes an adaptor plate to go from the W12 to an Audi manual gearbox - he makes the kit for the C5 RS6 and that shares the same bolt pattern as the W12... but... the kit is over $2,000 which I don't have.

Is the guy here in the states by chance? I know of someone that does the conversions for RS6, A6 4.2, A8/S8, etc.
BTW, I love that you are tackling this type of project with THIS powerplant. There are dozens of alternatives and ppl are always going to ask "why use this engine when you could use that one," etc...I like seeing a project that goes outside the lines of what a "normal" swap would be. I heard the same rhetoric way back in 1995 when I decided to build the world's first Scirocco VR6..MikkiJayne could understand I know!
Keep on trucking mate, I will be watching this post.

 

Could you get an insert made to fit the Phaeton flex plate? Or is that too big to go in the gearbox?

Too big to fit inside.

I'm pretty much out on a limb here as I can't find anyone who has tuned a W12 engine.

I've no idea as to what flywheel weight is a good idea, how much more power/torque I can get from this with proper tuned length headers, what size exhaust to go for, etc etc.

MG

 

Could you get an insert made to fit the Phaeton flex plate? Or is that too big to go in the gearbox?

 

awful nice car to steal the engine from...

 

I've finally got to stripping the Phaeton down.

With the radiator out of the way, you can really start to see the engine.

I hope to have the engine/gearbox out in the next few days but as I'm not sure which bits I'm using yet, I'm taking my time to remove everything carefully rather than blasting through stuff.

I have found someone who makes an adaptor plate to go from the W12 to an Audi manual gearbox - he makes the kit for the C5 RS6 and that shares the same bolt pattern as the W12... but... the kit is over $2,000 which I don't have.

So, I'm going to look into using a flex plate from an ABZ with 034 Motorsport Flywheel insert.

This would mean that the starter motor wouldn't reach so I may modify the gearbox casing and have a section of casing welded in from another gearbox and mount the starter motor on the gearbox rather than the engine.

After that, I'll have to bridge the gaps from the engine to the transmission around the outside of the bell-housing.

MG

 

Nice! Love that your willing to play with one of these. Cool motor. You are a glutin for punishment!

 

Just keeping the info coming on these engines.

I've recently been offered the loom and ECUs from an A8 D2 W12 in UK but the price was more than I have to pay someone who can tune the original Phaeton ECUs to run... and I get more bhp out of it too!

Someone has asked for the part number of the W12 engine/gearbox spacer plate so I figured I'd take a couple of photos and put them on here for everyone to see.

I'm getting closer to pulling the engine out of the Phaeton and have started parting it out.

After reading up about removing the engine, I found out that the sump isn't strong enough to support the engine when it's sitting on the floor and will break! The engine weighs 250kg!!

As a result, I've bought the VW Tool which locates into the bottom of the engine block which will allow the engine to sit safely and square to the floor. This will also help when I come to place the engine and gearbox in the right position on the chassis jig.

The donor vehicle...

MG

 

The only W12 swap I've ever seen was in a VW Fridolin...

http://www.volksforum.com/forum/showthread.php?t=13749

It looks like it only has a single ECU in this vid...

 

I'm currently driving the Phaeton W12 as my daily driver... it's not cheap on fuel! Especially as it's stuck in top gear as the transmission needs a rebuild. It that didn't mean dismantling the front end of the car, I would have done it by now.

So far, nobody has been able to offer to re-program the engine ECUs to run without the rest of the system.

That leads me to believe that either no one has ever done this or that at the moment, it's not possible. Maybe that will change in the future.

I've started looking for Audi A8 D2 ECUs (lots of those on ebay.de) and the engine harness. I think that this is probably my way forwards.

Having checked on some basics, the camshafts, heads etc are identical between the BAN (Phaeton W12) and the AZC (A8 W12). The throttle bodies have a different part number but then the inlet manifold is different also...

I've more research to do and to get another vehicle on the road so that this one can get taken apart.

MG

 

This gearbox is sold to a friend in Sweden. The reason I wanted to check it is that I have the choice of either an 01E 2WD box from a 2.5TDI or a Boxster S gearbox which is fundamentally the same as the 996 but has the diff on the other side to change the direction of drive.

I also spoke to MRC Tuning today about the possibility of having the ECUs chipped to code out can-bus etc. We'll see!

MG

 

Cos you just have a Porsche gearbox kicking about. Obviously

I found that the 924 box had more in common with the 3.6 V8 than the 012 from an A4. Weird coincidence?

 

Oh, and here's a few of the W12 spacer sitting against a Porsche gearbox.

Interesting that they share more in common.

MG

 

While doing to tidying up in the garage this morning, I found both my Audi fixed gearbox spacer and the W12 spacer that I bought a while ago for research purposes and they share 3 locating holes.

I've laid them on top of each other to see just how far out the rest are.

I realise that the photo needs rotating and will do that later on.

MG

 

I can't imagine the ECU needs much to run outside of the car. What are you putting it in? The only input is the throttle really

 

I bet you could do it with two aftermarket ECUs though (just like the RS4)

One to control fuel and ignition and one to control the cams - feed them both the same inputs but set them up and map them to do different things!

Or, one to do fuel and inlet cams and one to do ignition and exhaust cams, that way you can probably run full sequential, or at least batch fire and wasted spark

 

This has already crossed my mind. I need to look into what differences there are between the A8 W12 and the Phaeton W12 engines.

I know that the intake manifold is different but the cams, sensors, comp ratio etc could also be different and give me huge headaches with running problems.

Unfortunately this is one engine where an aftermarket ECU won't work due to the complicated nature of variable cams on both intake and exhaust etc.

MG

 

Did the D2 have CAN-BUS? If not could you use the electronics from one of those instead?