Feasibility of Audi W12 6.0 litre engine in a GTM

[bmw850]

Hi Everyone
I am brand new to the forum but have been thinking about building a GTM for some time now. There is nothing wrong with the V8's ofcourse (Mercury Racings SB 7.0 V8 looks a great choice) but I've always wondered about a V12 or 12 cylinder in a W formation for the GTM.

The engine bay is limited for space and the V8's are already a tight fit from what I've read on my research, so a V12 would probably be impossible without stretching the chassis and bodywork...very expensive and time consuming I imagine. But Audi's 6.3 litre W12 engine is actually smaller in dimensions than its V8 engine...perhaps that would be a possibility to work with the stock GTM chassis and body.

So I am just asking for opinions...I would be going for custom engine management as I am sure the Audi engine's stock management is very much integrated with the rest of the Audi car.

And just out of curiosity, has anyone installed or are installing a Mercury Racing SB 7.0 litre? I am hoping to start building a GTM very late 2017 or early 2018 and this looks to be a great forum with plenty of expertise and help available!

Thanks very much for any opinions or infomation
Sam (Sydney, Australia)

[Jim1855]

A local guy (Michigan) built a stretched GTM with a LS?? engine and a traditional automatic hooked to a differential rather than the transaxle system. He lengthened the body and chassis by a lot, 14-16" I think.
Jim

[carbon fiber]

There's going to be a problem with width at the top of the engine. The layout/position of the accessories is critical for fitment also. Not much room up top (shoulder area). You have to be able to reverse the intake also, the ls intakes are reversible. The ls engines are extremely compact for a v8 and that's what the GTM is designed around. $28,000 for the Mercury Engine? You've got to be kidding. I've got about $3000 in my lq4/ls3 head hybrid, around 550hp. There are a lot better places to spend the money. (Bodywork and interior for instance) $6200 for crate ls3. More than 550 HP in these cars is useless, put in a crate ls3 and be done. Not trying to be negative, but it's not realistic, and it's been discussed to death. If you do buy the kit, there are plenty of people with great info here to help.

[carbon fiber]

A local guy (Michigan) built a stretched GTM with a LS?? engine and a traditional automatic hooked to a differential rather than the transaxle system. He lengthened the body and chassis by a lot, 14-16" I think.
Jim

It looked TERRIBLE. (like a limo without rear doors) I'm sure it ruined the handling of the car changing the wheelbase too.

[bmw850]

Thanks very much so far for the opinions guys, yes, the 12 cylinder engine would be a very difficult and expensive build. I will have to do some detailed measure ments of the W12 and see what (if indeed anything!) can be done...and even if so it sounds like a fair bit of custom fabrication and modification.

I am sure the W12 already has dry sump lubrication...so I cant really gain any more clearance there as if it had a wet sump.The engine is for sale at the same time I am planning to start saving up for the GTM kit. Otherwise as was recommended, you cant go wrong with a LS3 V8! Thanks again guys.

[Just puttering]

I thought an R8 (V10) engine with the transaxle might be a consideration - although, I have not looked at the dimensions, I am sure it would be chore using this setup. I am sure that Finding the parts from an R8 would be a real cost savings over the LS options!


Yes the last part is a funny!

[bmw850]

OK Guys, thanks again for the opinions and info about my question. I hope to order a GTM kit in about 3 months, this is a great forum and I am sure it will be a fantastic resource when building the car. The Audi W12 block is good for length ,it is quite a bit shorter here than the LS1, but it is 1.5 inches wider and 2.5 inches taller.
Would anyone be able to see how much clearance their GTM has with a LS V8 block ..thanks very much if anyone does'nt mind doing this! 1.5 for width and 2.5 inches for height does'nt sound like a huge difference but I have heard the engine bay is tight for space, so it may still be too much for the stock chassis engine bay.

As for the R8 option..it does sound good , it can come with a manual transmission designed for that V10 as well! But as you say, still very expensive!

All the best to the forum! Sam

[carbon fiber]

Here's a couple pics (I think I have every pic of a GTM ever taken) that show how tight the ls fits in the GTM. The places where you'll have trouble is up front where the accessories are, and between the frame rails where the exhaust is. It would probably take some surgery on the frame in "width" and a re-shape of the "waterfall" area. If it's 1.5 inches wider and 2.5 taller the exhaust manifolds will probably be where the frame rails are, and the accessories are going to be where your shoulder/arm is. Again not trying to be negative, just you're probably looking at some mods if you want that engine. If you don't know there's another site called ffcars.com, and they have WAY MORE info on the GTM there. There are multiple threads there about v12 swap ideas.7222278.jpg223513d1448290864-anyone-wish-they-had-power-steering-power-brakes-009.jpgDo your homework before building. There are some mods that are desirable and some that are necessary, like a clutch stop that can save you from destroying your engine. (Too much clutch travel/pressure can ruin the thrust bearings) Look for the thread "Transaxle Tic-Tic! Need Help Please!" on ffcars.com. There are multiple threads about bodywork also. Know what you're getting into. Like I said, do your homework...

[bmw850]

Thanks very much for the feedback carbon fiber... your thoughts and the links to ffcars.com are very helpful. Plenty of homework for sure! Some builds have taken years....I really would'nt want to wait that long but am willing to be patient for the possible W12 installation. I'll take a close look at the ffcar threads and let you know how I get on...I am hoping to receive the kit early 2018 at the moment.
All the best and thanks again!