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Top Secret V-12 Toyota Supra Twin Turbo

Twice the Cylinders, Twice the Power.

Dino Dalle Carbonare
Oct 2, 2007 SHARE
0710_turp_8_z+top_secret_toyota_supra+left_front_view Photo 1/8   |   Top Secret V-12 Toyota Supra Twin Turbo

Right when you assumed every possible engine swap and conversion have already been done, Top Secret comes by and stuns everyone. While it's difficult to come up with unique, never before attempted projects, Top Secret's Nagata-san manages to do it year in and year out. Last year it was the VQ35DE powered BNR32 Skyline GT-R and before that it was the twin-turbo V-8 powered V35 Skyline 350GT. For 2007, they've gone one better - if that's even possible. Behold the Top Secret V-12 Supra!

In 2006, when thinking about his next Tokyo Auto Salon (TAS) project, the tricky part for Nagata-san, aka Smoky, was making sure this particular car would top all of his past creations. And, to make things even harder, his choice of base cars was sort of restricted, seeing as how slow Japanese manufacturers are handling the development of their next batch of high-performance sports cars. As such he resorted to a car he knows very well, the JZA80 Toyota Supra. The Supra's large-engine bay opens up a lot of possibilities when it comes to engine tuning and engine swaps, and Top Secret has done everything from a T88 powered, 2.2L, four-cylinder, 720ps 3S-GTE to a 1,000ps RB26. But Nagata-san wanted to go one better by doing something completely crazy on the engine front and nothing really beats shoehorning a V-12 into the engine mounts!

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The only Japanese-produced V-12 engine, the 1GZ-FE from the Toyota Century, fitted the bill perfectly even if it wasn't very easy, or cheap, to source. Of course it didn't end there, after all this is Top Secret we're talking about. Smoky wanted to go all out so he threw two HKS GT-RS turbines into the equation in the pursuit of a little more performance, since Toyota's 4,996cc V-12 is somewhat lethargic with a maximum output of only 280 ps at 5,200 rpm. It isn't even too impressive on the torque side of things, with only 46.9kgm developed at 4,000 rpm. So with the engine in hand the work began with laying out the twin-turbo system and the endless modifications required on engine swaps of this nature.

With considerable time constraints to get the car ready for TAS, Smoky decided to keep the 1GZ in standard tune and see what could be achieved by force-feeding it a low amount of boost. The engine was mounted as low as possible in order to allow enough space for the custom inlet plenums to be fitted on top of the two banks. This created a few problems with the sump, which had to be scrapped. So Top Secret swapped a very thin custom aluminum sump, which ended up considerably cutting the sump's oil capacity. To fix this problem, Top Secret created a one-off semi-dry sump setup. Ogura Clutch helped by building an external oil pump which was mounted low-down and belt-driven directly from the crank pulley. Large diameter oil lines help to distribute the oil where needed, keeping the engine's internals nice and happy.

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Then, a set of exhaust manifolds were made to fit the GT-RS turbines. From this point on it became a bit of a piping nightmare, but the result is nothing short of exceptional. Once the compressed charge leaves the front-mounted intercoolers it's fed to opposite banks of six-cylinders via custom manifolds. The electrical throttle system of the stock 1GZ was dropped in favor of two N15 Pulsar mechanical throttles. In typical Top Secret style everything, including the engine covers, was polished to a mirror finish.

0710_turp_019_z+top_secret_toyota_supra+interior Photo 4/8   |   Top Secret V-12 Toyota Supra Twin Turbo

Even if the engine was positioned as far back as possible there's still a hefty weight hanging over the front end so they decided to shift the radiator all the way to the back of the car. Bespoke piping was laid underneath to take the hot coolant to the radiator, while a return pipe takes it right back into the engine. Two oil coolers were thrown in for good measure and positioned in a V-mount layout with the intercoolers. With a few modifications, the stock JZA80 six-speed Getrag transmission was fitted and mated to an ORC twin-plate clutch.

0710_turp_022_z+top_secret_toyota_supra+engine Photo 5/8   |   Top Secret V-12 Toyota Supra Twin Turbo

Even in this configuration the numbers are astonishing. The boosted 1GZ churns out 650 ps, thanks in part to the custom engine management system made up of two HKS F-Con V Pro ECUs and a set of Neko AF700 oxygen sensors. Nagata has big plans for this engine and work has already began in the development of custom engine internals to allow the 1GZ to rev up to 7,000 rpm (1,000 rpm up from stock) and take significantly more boost. The target was set at over 800 ps, not a very precise number but with hardware like this it wouldn't be surprising if the final figure reached the magical 1,000ps benchmark.

This Supra was built to be a comfortable yet fast road car and there will no doubt be a few high-speed trials to see if it can beat the 341km/h that the V35 GT-R project achieved at the German Autobahn in 2005.

0710_turp_023_z+top_secret_toyota_supra+left_rear_view Photo 6/8   |   Top Secret V-12 Toyota Supra Twin Turbo

The V-12 Supra project was also undertaken to take the Supra model aesthetically to a new level. As a final goodbye to the JZA80, Top Secret designed and built a complete widebody kit called "Final Evolution." The 600,000 Yen kit has already captured the imagination of many Supra owners and Top Secret is overwhelmed with orders from both Japan and overseas. The kit was designed with a very angular feel, much like modern-day Lexus models and concept cars. The factory headlight clusters were binned and replaced with original Top Secret projector-type items, completely altering the front-end look. A long-snout front bumper with a large central opening joins the lights together with the aggressively flared arches to create a totally bespoke look. A vented bonnet helps extract air from the engine bay or, in this case, the V-mounted intercooler and oil coolers. The angular-design is carried on to the side via the deep skirts and is joined with the flared overfenders.

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Also part of the kit is the rear bumper, which completes the Top Secret conversion with an abundance of air outlets to keep the radiator happy. The main radiator air intakes are located near the B-pillars where the small side window used to reside. A Carbon rear wing joins the Ganador mirrors to complement the "Final Evolution" JZA80 look.Shot with Bridgestone RE-01R rubber, Volk Racing GT-F 19-inch wheels were painted with gold highlights to match the Top Secret color scheme. Making it hard to miss is a huge GReddy 8-pot brake kit up front and 4-pot kit at the back with matching gold calipers and center bells. The V-12 Supra has been lowered thanks to a set of Top Secret Aragosta adjustable suspension.

0710_turp_029_z+top_secret_toyota_supra+gauge_cluster Photo 8/8   |   Top Secret V-12 Toyota Supra Twin Turbo

Keeping with the idea behind this project, the interior hasn't been stripped out but dressed up to make it a comfortable place to be. A Pioneer double-DIN HDD navigation unit and full speaker system takes care of the entertainment, while occupants are cosseted in lightweight, carbon-shell leather Bride bucket seats. Other toys include the new-generation HKS EVC boost controller and Defi Super Sports Cluster dash unit - both integrated seamlessly into the dashboard. Opening the glovebox you'll find two HKS F-Con V Pro computers and AF-700 lambda displays, while the Top Secret steering wheel and gear knob finish things off.

We're eager to see how this V-12 Supra project develops and if Smoky can turn it into his fastest road project ever. With Smoky's track record it is only a matter of time before that happens.

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By Dino Dalle Carbonare
122 Articles

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