It’s been several years since we last had an update on this mad project build. At the time, details were sketchy about whether it would ever be finished and what it would even power, but wait no longer.

    The conjoined twin Supra motors are finally running and we get to hear that glorious sound on the dyno!

    Originally surfacing on internet forums around 2014, the poster wrote about a project his mysterious uncle was working on for several years:

    So I’ve got an evil genius uncle, the guy is a mad scientist, genius, master craftsman, you name it… it’s amazing what he does.

    I swung by his place last night to see his next project…. splicing two 2JZGTE (Supra Twin Turbo) engines together into a single crank operated quad turbo V12.

    … it’s coming together quite well

    Although it would appear they are two 1JZ engines (not 2JZ as he mentioned), the thread goes on to outline the project’s status (per the 2014 thread):

    • Block made from cutting the bottom end off two Toyota Supra inline-six cylinder motors (1JZ-GTE from what we can see)
    • Machined, welded, stress relieved and align bored a crankcase for 120-degree V angle.
    • Purchased a custom crankshaft from Scat with small-block Chevrolet main bearings, Honda rod bearings and h-beam rods
    • Bolted cylinder blocks to crankcase using Toyota oil drain back holes modified
    • Reversed one head so there are common ports to the centre of the motor
    • Put the exhaust ports to the centre just for giggles. This part has us a little confused, earlier photos show the turbos hanging out the opposing sides, which tends to make more sense.
    • Fabricated an oil pan from three-quarter-inch aluminium plate and mounted a dry sump pump.
    • Built two cam drives and a serpentine drive for the alternator and twin water pumps
    • Started exhaust headers… no intake yet.
    • This is a 5.0-litre turbocharged to a target of 800hp (with centre-exiting exhausts, we assume this will eventually be a big single?)

    Originally found in the earlier model JZA70 Supra, the 1JZ is the little brother to the 2JZ, displacing 2.5L instead of the 3.0L 2JZ. But don’t let that fool you, the engine is still one of the most legendary units to come from the Land of the Rising Sun.

    Fast Forward to 2020

    Now, fast forward five years and the V12 monster is complete, albeit with some changes to the turbo setup!

    V12 Twin Turbo 4JZ First Dyno

    As per the description in the dyno video, we get a little more insight into the build:

    Don Groff’s incredible 1JZ V12 Twin Turbo first dyno session at Nth Moto.

    Every piece of this car was meticulously built from scratch by Don in his workshop.

    The V12 engine was made by joining two Toyota 1JZ 6-cylinder engines together at the crank using a custom crankcase that Don developed and fabricated himself.

    It has been an honor to play a small roll with Don’s historic project, and all of us were ecstatic to see the car make over 800 HP on it’s first dyno attempt!

    The twin turbo engine sounds were unreal and so exotic as the RPM increased – something a video will never do it justice.

    17.5 PSI manifold pressure provided 810.3 HP and 699.9 lb-ft Torque on E85 fuel.

    The project has obviously changed direction at some point, as we can see the idea of quad turbos was scrapped and then transformed to a more traditional (if you can call jamming two blocks together traditional) twin-turbo setup, one for each bank of six cylinders.

    We can’t wait to see more about this amazing build. A huge thank you goes to to Don Groff for making many Toyota fan’s dream become reality, and the NthMoto for the videos.

    Toyota 4JZ? Mad man builds a twin-turbo V12 from two Toyota Supra motors!

    NthMoto Youtube channel shows some first start/drive videos below:

    Mark Trueno

    Mark Trueno is a CarExpert Contributor.

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