ROCKY AUTO’S RB30 POWERED FAIRLADY Z
UDino Dalle Carbonare
PMay 10, 2012
Composite materials and billet aluminum are probably the last two things you would associate with a vintage car, but for Watanabe-san of Rocky Auto these are the materials of choice when creating the most unique restorations we have come across in Japan. Actually scratch that; what Watanabe-san does is more like modernizations, making everyone’s favorite old cars from yesteryear feel and sound like something a little bit more up to date. This is probably the point when purists would cringe, but Rocky Auto isn’t out to please everyone…
…plus it’s not like Japanese vintage rides like the S30 Fairlady Z don’t get heavily modified as it is. Rocky Auto just does it with that little bit of extra flair, something that one of their latest project perfectly demonstrates.
We will get to the carbon fiber exterior a little further down, first up is the glorious sound emanating from under the hood that I want to concentrate on. There’s a certain something about the raspy straight six-sounds this S30 produces; the carbed throttle response is definitely there, but the induction and exhaust noises have a certain added quality. It’s hard to put a finger on what it is…
…until you have a look at the engine itself. The upwards-arched exhaust manifold is very S20-like, but the unmistakable shape of the cam covers means this could only by an RB26 head.
But it’s an RB26 head with a bit of a difference because it has been stripped of its electronic fuel injection and replaced with a triplet of 50 mm Solex carburetors.
The idea here was to mate the reliability of a modern engine, with the character that made these cars so appealing in the first place. Each of the six intakes have been fitted with a custom funnel, just the right length for good clearance in S30′s engine bay. Rocky Auto had to make the throttle linkage and the aluminum pivots too, as well as the spacer plate onto which the carburetors are mounted onto.
But it doesn’t end there. The RB26 head is bolted down into an RB30 bottom end, sourced and shipped to Japan from Australia. As Watanabe-san explains, the idea here was of course to be different but at the same time make the Z as fun to drive as possible. The 3 liters of capacity help low-end grunt, rewarding each prod of the throttle with instant torque, available all the way from 2,000 rpm. And with this being an RB it loves revs too, the 270˚ camshafts helping it develop just over 300 HP at about 7,000 rpm. It might not sound like much but when you consider this car hits the scales at 1,040 kg, that is ample performance for some serious fun on both the street as well as at the track.
The RB30 was located as far back in the engine bay as possible, sitting on custom fabricated mounts that are welded onto the fully restored chassis and custom front tubular subframe.
The Rocky Auto 46 mm 6-into-1 stainless steel manifold guides spent gasses towards the custom exhaust system, which has been designed to offer just the right amount of back pressure to match the engine’s performance.
Here is a closer look at the radiator Rocky Auto had Koyo fabricate, sporting a side-flow design and an electrical fan to keep the engine running cool even when stuck in those massive Japanese traffic jams. What we don’t see are the changes made to the driveline, which consist of a Nissan 5-speed transmission borrowed from an R32 Skyline, an ATS carbon clutch and a Cusco 2-way LSD. OS Giken supplied a close ratio conversion kit for the gearbox that shortens the first three cogs, making the Z pretty responsive and accelerative.
Prior to the build, the donor S30 chassis was thoroughly restored, rid of all rust spots and stiffened thanks to a dose of spot and seam welding. A custom multi-point roll cage was fabricated and welded in place, something that works wonders at further boosting torsional rigidity of the vintage shell.
What followed was some pretty impressive custom suspension work. A whole rear subframe was machined out of billet aluminum and bolted onto the chassis via solid bushes.
Billet front and rear suspension arms followed, again with no rubber or polyurethane bushing anywhere, metal on metal for the best possible handling and steering feel. Careful thought was given to the overall geometry, taking into account roll centers, camber and toe settings in order to give a very modern feel to this close to forty year old car. Rocky Auto adjustable coilovers were next, bolted down to reinforced top mounts front and rear.
The ride height has been set nice and low, or as low as you want it to be to have a functional and drivable car on the street. The choice of wheels couldn’t have been a better one, the Volk Racing TE37Vs boasting lightweight forged construction, a perfect addition to this modern take on the S30. The rims measure 9J by 15-inch up front, with slightly wider 10J by 15s at the rear. Hiding behind the spokes of the wheels…
…are a set of R32 Skyline 4-pot calipers fitted along with slotted discs. At the rear single pot, slide-type calipers have been deemed more than up to the job.
And so we get to the body. Watanabe-san has never been one to shy away from using carbon fiber on his cars, and has always wanted to go a little wilder. This was his chance. The whole front section of the Z sports carbon fiber, parts like the bumper, the lower grille and splitter section and of course the hood.
The fenders and bolted on flares are also carbon, wet carbon to be precise. In an attempt to match the rest of the body 3M carbon-fiber-look vinyl has been added to the lower section, as well as…
…the doors, which have been left metal and thus required a similar finish. The side mirrors are carbon-look too and have integrated LED turn signals for yet another modern touch.
The carbon treatment continues rearwards…
…where the wrapped rear fenders meet the hatch, taillight panel and bumper all constructed in wet carbon.
You either love it or hate it, but whatever you think about this Rocky Auto S30 you can’t help but appreciate the amount of work and attention to detail that has gone into it.
Out on the road it simply looks fantastic, the carbed RB30 spluttering and backfiring on the over run…
…as it cruises the streets in Okazaki, where Rocky Auto is based.
The interior is a very focused place to sit in. Everything has been done to boost the experience and serve up an optimal driving position…
…which begins with a pair of Bride bucket seats and Sabelt harnesses.
Behind the Momo Corse suede steering wheel the aftermarket instrumentation has been neatly fitted inside the instrument binnacles of the stock dash.
The car has been stripped of the heater controls but you can manually “open the tap” and allow the hot radiator fluid to flow around the heating system and keep you nice and warm in the winter months. In summer you sweat.
Further weight was shaved off by replacing the door cards with a sheet of carbon fiber.
Watanabe-san is more than content at how his carbon S30 has turned out, his unorthodox approach to restoration and tuning building upon what made this Japanese classic so special. He has to keep moving forward however, so has decided to put the car up for sale so he can make space for his next project. Apparently it will involve an old Skyline and a VR38DETT. This, we will definitely have to see!
-Dino Dalle Carbonare
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