Here at Modified we are no strangers to the kind of work done at JUN Auto Mechanic. Over the years they have established themselves as builders of the most extreme projects in Japan. And what makes them different from a lot of tuners out there is that they build their cars to meet specific goals. From Skyline GT-Rs and Toyota Supras, to Subaru Imprezas and Lancer EVOs they have worked with them all and achieved some amazing results. Having a state of the art machine shop does help when requiring custom parts, but it’s the engineering and problem-solving capabilities of the JUN team, headed by Koyama-san, that sets them apart from other shops. In recent years they have built Kumakubo’s D1 RWD Subaru Impreza from scratch, effectively turning an all-grip 4WD rally-bread machine into a RWD drift monster. Kumakubo won the 2006-07 D1 Championship with the Team Orange Impreza, and has been so impressed with the quality of work at JUN that he is having his new 2007-08, yet-to-be-announced, D1 car built by them. Daijiro Inada, the father of Japanese tuning, founder of Option Magazine and the D1-GP had his Silver State Classic 900 HP Option Stream Z built by JUN. But their newest and latest project really does take the cake. Don’t let the similarity to Inada’s Z fool you, the car you see in these pages is a totally new machine, a car that beneath its menacing body hides some of them most ambitious conversion ever successfully carried out by a tuner. This is the totally bespoke JUN 350Z-R-4WD.
The 350Z is undoubtedly a superb car in many ways. It has proven to lend itself very well to all sorts of tuning. Supercharging, single and twin turbocharging and of course your good old-fashioned NA tuning. It has had much success in motorsport too from Super Taikyu endurance racing to the full-on GT500 class of Super GT. Despite all of this the 350Z has never really been a contender in the highly modified, no-regulation, circuit-racing scene. Currently dominated by household names like Skyline GT-Rs, Lancer Evolutions and Mazda RX-7s, the Z is completely overshadowed by these cars. So with this in mind JUN was commissioned by a Hong Kong enthusiast, and good JUN customer, to take 350Z tuning to a totally new level. The plan was set to create a high-power, all-wheel drive, twin-turbo 350Z, the first of its kind in the world. An all-wheel-drive Z33 was already made a few years back by Zele International and raced at Pikes Peak, but that car had a GT-R engine and drivetrain swap. What JUN were asked to do was to keep the VQ35DE and devise a custom 4WD system. Not an easy task to say the least. On the engine front JUN was already a step ahead as they had done an immense amount of research into force-feeding the Nissan V6 with the Option Stream Z. This time round a more responsive set-up was required so it was preferred to go with two turbines rather than the one used on the top-speed Z. Combined with the recently released JUN 3.8L stoker kit for the VQ the twin TD05 Trust blowers would offer potential for good response, powerful top end and a killer mid-range. On paper everything looked good but some tough decisions had to be made on where to actually put everything. Thoughts on the 4WD system were already being put to paper and it became evident early on that the turbines had to be mounted high up in the engine bay to leave enough room for the drivetrain components. So the engine part started with the 3.8 L kit being fitted to the prepped block, which included some very tough cylinder liners ready to take the abuse of the compressed intake-charge. Lots of work went into the heads with a hefty dose of porting and polishing to assure the best possible throttle response. The JUN machine shop carved up a set of 272º duration bumpsticks, which would allow for 10.8 mm of valve lift while non-VTC cam sprockets were also made up. The head work was finished off with titanium retainers and special valve springs to guarantee the best possible performance. The stainless steel exhaust manifolds had to be hand made and shaped, allowing for the rear-engine placement of the turbos. The two Trust Type-R external wastegates were placed low down below the engine where the short screamer pipes can release the unwanted exhaust gasses. The exhaust system was kept simple, and in true racecar feel was routed straight from the turbine into the front fender and out the side, just like Super GT Z’s!
At this point the chassis was being prepared. The red donor 350Z was stripped down to bare metal and work began on the spot welding and various modifications needed to fit the custom 4WD layout. The engine was dropped into its new custom mounts, as it needed to be in place to make sure all the other drivetrain components would fit perfectly. The sump of the VQ was taken from the JDM-only M35 Stagea, which is available with 4WD system and a VQ engine. This was the perfect choice as it came with everything needed, diff housing and drive shafts. Cusco was called in to make up a one-off LSD for the front end and everything was sealed up and ready to go. A V35 Skyline (Infiniti G35) front subframe was used and modified to fit and clear the suspension parts. JUN made custom adjustable upper arms, which were fitted to Y50 Fuga (Infiniti M35/45) aluminium hubs and lower arms. The hubs allowed space for the driveshaft while custom mounts were made for the dampers. The rear diff-housing was fitted with a Cusco LSD and bolted to the custom built subframe. Suspension layout was changed with custom and adjustable lower arms made up and new mounting points for the dampers, which were made by ZEAL to JUN’s own specification. The factory 6-speed transmission was relegated to the trash and replaced by a Hollinger 6-speed sequential which was in turn fitted to a BNR32 GT-R transfer case (with ATTESA-ETS system). This has the job of sending drive to the front differential via a thin propeller shaft, while the main propeller shaft was taken from an M35 Stagea. At this point the project was beginning to take shape and with most of the mechanical side taken care of the car was once again stripped and sent to the body shop for painting.
Once the engine found its way back into the chassis it was time for the remainder of the ancillaries to be fitted. Custom bracing was constructed to hold the V-mounted radiator and twin oil-cooler set up. The large-core side intercoolers were then positioned, and work began, shaping and fitting the aluminium piping. Each bank of three-cylinders feed themselves the compressed air, which is guided from the intercoolers via the long intake pipes, past the two mechanical throttles, into the main intake plenums and into the six cylinders. To keep intake pressure equal on each side of the engine a balancer pipe was welded in just before the throttles. A very eye-catching carbon engine cover joins the trademark yellow cam covers to finish things off under the hood. With a target weight of 1,300 kg there was only one thing that needed to be done to the interior, strip the hell out of it! All the wiring was redone and repositioned for easy access on the passenger side while the center console houses most of the switchgear which was removed from around the steering column and various other locations. Since the Hollinger gearbox is shorter than the stock item a new gearshift opening had to be made in front of the factory one, which is where the custom made gear selector sprouts out from. Its curious design permits it to clear the center part of the dash as well as be at hand’s reach for blistering fast gear-changes. The factory instrumentation has been replaced by a Percul Lapcom DP-1001 dash unit, which keeps the driver informed with all sorts of information from the engine’s sensors. The Racelogic Drift Box Pro allows for accurate measurement of performance as well as providing cool functions like data logging and plotting of track position allowing the user to perfect his best line around a track. Boost control is handled by the GReddy e-01 while the BNR32 front-torque gauge lets the driver know when power is being sent to the front wheels via the ATTESA-ETS system. The driver sits in the full race bucket Bride seat and has a nice alcantara-clad Sparco steering wheel to play with. The exterior of the car has been finished in true JUN style with the trademark yellow paint scheme. Ings provided the front bumper, side skirts and rear bumper but a lot of work was done by JUN to modify the kit for this car. First off the hood is a totally custom item designed to aid in cooling of the V-mount set up and keep those high-mount turbines nice and cool. The front fenders mimic the look of Super GT Zs thanks to the carbon venting and of course the oval-cut exhausts. Other special items include FRP doors, acrylic windows and carbon rear hatch, all in the interest of saving weight. More carbon has been used for the front bumper canards, side mirrors, rear diffuser and the SARD GT-style spoiler. Finishing things off is a set of lightweight Advan RG-II 18-inch wheels shod in Advan A048 rubber. Maximum brake performance is guaranteed by the Endless 6-pot front calipers, which bite down on huge 380 mm discs. The rear is stabilized by 4-pot calipers and 332 mm discs, again from Endless.
The 350Z-R-4WD has been on shakedown testing since late December when it made its first outing at a very wet Tsukuba circuit during an Option Magazine time attack session. With a maximum power output of 790 hp and a monster 723 ft-lbs of torque to play with, the wet conditions were a bit too much even for the 4WD drivetrain to handle. The car has been out a few more times for further ECU mapping and suspension set-up and managed to record lap times of around 58 seconds at Tsukuba. The car still needs one last track outing to get everything tip-top before it is shipped off to its owner in Hong Kong where it will be used as track weapon. As ever we would like to thank all the guys at JUN for allowing us access to their workshop and shoot the car. Now the question on everyone’s lips is will JUN be able to go one better with a future project? We really can’t see how this could be possible, but we look forward to being proven wrong!