V12 engine for COUNTACH replica

Hi there everyone!

I have been following this forum ever since I was a teenager - and I am finally in the position to build a replica car. I absolutely love the GT40s, and I am planning to build one - but for now - I came across this Countach replica that I want to finish first.


The first thing on my to-do list is to chose an engine - and I would like to use a V12, either:

- BMW M70
- BMW M73
- Mercedes Benz M120
- Jaguar V12

Unfortunately, I do not know what is needed to make them "run as a stand-alone engine" without having to purchase an expensive motor management unit.

Do you have any information, links, friends or further details on what is needed to make any of these engines work "stand alone"?

I guess only the Jaguar V12 is running a single distributor correct? That makes it "more of a real V12" than the others that all run 2x distributors.

Then I can use a Holley EFI system - with TBI (throttle body injection) - these systems don't necessarily need to know how many cylinders are firing. They can be setup to "only do fuel" not spark...
Fran Hall from RCR can make a complete kit for using a Porsche G96 on the BMW M70 as well. I guess this is all custom and anything can be made.

Thanks for the link on that gearbox adapter plate. I guess I would use the G31 instead of the Audi 01 gearbox, according to this post, correct?

I am not yet done on the engine selection - I want to ideally run a Holley EFI and control timing myself. Does not need to be sequential fuel injection, TBI is enough.
These are for sure nice engines - but I can buy M120 Mercedes Benz V12 engines over here (same that are used in the Pagani Zonda) for just under 5k. So this is my primary choice - I want to use my money on a GT40 replica thereafter, so I want to be mindful with the budget.
The M120 would be very easy to adapt a megasquirt ECU to.

The M275 would really be the business, but I'm not sure if it has any variable valve timing. Then you start getting into challenges.


Mortified GT
I have an M275 in one of my builds, still unsure of which transaxle will take the 650ft/lbs torque. Motec.
I had one in a SL600 13 years ago. Motor mounts and rear tires were short lived. I also had the Rentec ECU upgrade and was told it upped it to 750 ft lbs.
Have you checked to see if a V12 will fit in that specific car? I really wanted a V12 in my Miura build. After checking the engine lengths of available V12s (same ones being suggested here), none would fit in the chassis when mated to available transaxles. My situation was different in that the engine position is transverse but is similar in that it's fitting a long engine into limited space. The original Countach had a V12 but with a very unique transaxle arrangement. I think there's a good reason you see V8s in Countach replicas ... just saying :)
Hi Joel, absolutely agreed, so I took some measurements from the sketch of the frame that I have. It isn't much space - I was originally intending to 3D-scan the body and the frame, then scale the car up by 10% - but I have too many projects going on so this must wait for now and I need to focus on this build kit as I have it.

According to this sketch, I have about 795mm for the engine in length - not much at all. This already requires the transaxle to be pushed back a little and the driveshafts not running on a slight forward angle.

I think the VW W12 engine would fit best: they measure about 520mm in length and about 710mm in width. Perfect for this project here. Unfortunately my frame is 1992 and I am only allowed to use an engine that is 10 years younger, so engine must be 2002 otherwise I cannot register the car. I do not have a correct size for an M120, but it is likely more than 800mm in length, so not the best fit for this chassis.


These are very long engines too.

Definitely worth checking for fit, including transaxle mounting face to output flange, plus bell-housing / adapter length.


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Those are some very sketchy looking rear wishbones. What controls the rear wheel toe in / out?

I totally agree with you. I need to modify them - with a single spherical rod end bearing where the upper wishbone connects to the case upright. Does this make sense to you?


Mortified GT
I’ve used a set of my Southern GT uprights and suspension on my Diablo build, as per SGT40 geometry. All fully adjustable and fits the 335 rears, all just inside the rear arches.