Update: Twin Turbo V12 Dual-1JZ Project Humming Along


Back in December, we showed you Don Groff’s unique home-engineered twin-turbo V12 project he’s building up from a pair of Toyota 1JZ engine blocks, and we recently heard from Don with some updates on how the project is progressing along. Originally, the plan was to use four turbochargers as you’ll see in the initial article linked above, but Groff has since changed the plan to use a pair of Garrett turbochargers that will support 550 horsepower each.

“I mated the engine to the transaxle and started the process of how to package everything that needs to be located. I think I have a plan and made some PVC frame rails to help visualize where they need to route. Also, there is a new linkage mechanism so the six-speed can be shifted from up front with a pair of Morse push-pull cables,” says Groff.

Various stages of engineering.

Custom builds like this are no small feat – the number of components that need to be located, how they interface with one another, and whether they will actually perform properly in that final location are one of the biggest challenges.

Groff subsequently used those PVC framerails to determine that the chassis would require removable sections to allow for transaxle removal in the event of a mechanical issue.

“I mounted the turbos and roughed in exhaust pipes. I have plans for the waste gates and blow-off mounting, but will hold off for some other priorities. I am waffling on mufflers,if any,” he says. Who needs mufflers when you’ve got a pair of turbos to keep the engine sounds under control?

The Herculean effort of making everything fit, and work properly, in the space he has to work with.

Other challenges had him moving the radiator and intercooler location from their originally-mapped position in front of the rear tires; he subsequently moved the radiator and intercooler into the location where he had originally planned for the fuel tank to reside. This will require a new fuel tank location, which he hasn’t decided on at this point.

This is one of the more unique garage-based projects we’ve seen in quite some time, and we thank Don for sharing it with us. We can’t wait to see some video of the car all done and running!


Moving right along. Well, almost. Can’t wait to see this one moving under its own power!

About the author

Jason Reiss

Jason draws upon nearly 15 years of experience in the automotive publishing industry. Collaborating with many of the industry's movers and shakers assists him in the creation of compelling technical articles and high-quality race coverage.
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