This is not the first time I've found myself sitting shotgun with Kitabayashi-san of Pentroof. A few years ago he terrified me on this same stretch of road, adjacent to the recently expanded Haneda airport on the extremities of Tokyo. Back then he was banging through the gears of his Z32 demo car, as its 670hp VG30 made traction a big problem all the way through the first three gears. But the BNR34 I'm sitting in now is all about grip, having absolutely no issue deploying all of its 680 ps fuss-free. It's the delivery that's the most shocking, showing just how much RB26 tuning has progressed even now with the new V-powered GT-R stealing the limelight. The truth is, running close to 700 hp, the Skyline GT-R has never been as easy to tune as today, as part development continues at what seems like an unseen rate.
To find out what makes this R34 such a great overall performer, one only has to look at what has been done to the engine. Simplicity and a coherent choice of products has been the key in building the white-topped RB26, coupled with some exceptional fine-tuning that can only be realized through years of experience. Kitabayashi-san began the build with a cleaned stock block, adding +1mm oversized HKS forged pistons, lightweight H-beam connecting rods, and a re-worked crankshaft. The 87mm bore and slightly increased stroke combine to increase displacement to 2.7L, while correcting the naturally poor harmonic balance of the RB26 at high rpm.
To guarantee an elastic power delivery with a fuller low-end torque curve, the head was polished and fitted with upgraded HKS valvetrain goodies, including a V-Cam Step 1 Type-B variable valve timing system. This, combined with the slightly larger HKS exhaust camshaft, gave Kitabayashi-san great control when tuning, boosting torque at lower to mid rpm to get fat, flat torque production all the way to an 8,000rpm redline-680 horses, developed at only 1.5 bar of boost, from a Trust T78-33D single turbo. No form of filtering is used on the T78, just an anodized HKS velocity stack to maximize air intake, but behind that it's Trust all the way, with a Trust external wastegate, Profec B boost controller, and full lightweight titanium exhaust fitted with an Apex sports catalyst to keep the authorities happy. HKS supplied all the requisite intercooler and hard piping, while a Nismo GT plenum boosts response thanks to its finely balanced air delivery characteristics. 1,000 cc/min Sard injectors are fed by the Sard fuel system and despite their size, never seem to hinder cold or hot starts, allowing the engine to crank into life instantaneously. An HKS oil cooler and Trust radiator permit key temperatures to be kept under control, and are helped along by upgraded JUN oil and N1 water pumps. An extended Trust oil sump allows a few more liters of oil to be kept in reserve, helping keep reliability high in such a highly tuned motor.
Kitabayashi-san has a reputation for being a master ECU programmer and it really showed when he took the car out on the road for our short demonstration. The HKS F-Con V Pro has been mapped on the dyno but tuned on the street, and closely linked to the HKS V-Cam which is optimized to shift timing, creates a very modern feel from an engine that is now over twenty years old. Those 680 horses are developed at 7,200 rpm, while the 506 lb-ft of torque peak at 5,800 rpm. But torque comes in at just below 3,000 rpm and 1.5 bar of boost develops at just over 4,000 rpm. As I gawk at simply how much bigger this setup makes the engine and turbo feel, Kitabayashi-san smiles and says, "You should feel it on the Wangan!"
And let's talk about its performance on those Japanese open highways Kitabayashi-san referred to. He confirms this R34 has seen at least 340 km/h out there-just over 211 mph. Needless to say, he wanted every aspect of this car to perform at its full potential, so every area had to be enhanced with top-level parts, beginning with the brakes: lightweight, monoblock Brembo six-piston calipers, fitted with floating, two-piece, slotted 380mm discs up front, and four-piston Brembo calipers and similar 370mm discs in the rear. An Ohlins PCV adjustable suspension takes care of the handling, offering a progressive feel which makes them suited both for fast street as well as circuit driving. Cusco adjustable upper control arms allow for camber to be adjusted at will, while pillow-ball tension rods add a tighter feel to both steering and handling. The final touch in the set up is the Yokohama Advan rubber fitted to the black Volk Racing TE37s. These new AD08 Neovas offer race levels of grip and are superb on wet roads, making them the perfect overall choice for a car of these capabilities.
The exterior is all Nismo-a Z-Tune front bumper, wide front fenders, side and rear skirts, Super GT LED taillights, and an R-tune dry carbon hood. As Kitabayashi-san tells us, the rear spoiler has been ditched in favor of something more substantial to a car that can blast high speeds on public roads, and also quick lap times around a circuit. Supplied by Top Secret, this carbon rear piece has the size, shape and currently the positioning required to provide the precise amount of downforce needed at high speeds, but can be re-adjusted for lower-speed track driving when needed.
"Revision 2" BNR34s, like this one, received an interior clad with darker seat and door trim fabric, as well as brushed aluminium pedals. Since this is a daily driven car, comfort was a priority and the stock seats remain, but are joined by a Takata harness when the situation calls for extra restraint. And all that looks right at home with Nismo 320 km/h dials, an Alcantara-clad steering wheel, Trust Profec B boost controller above the coin holder, F-Con V Pro ECU in the passenger footwell, and the Nismo Version II upgraded MFD LCD display (which throws in functions like the G-meter graph). Since the V-Cam controller needs not be fiddled with, it has been tucked away into the glove box, a gadget that only Kitabayashi-san is allowed to play with! The Alpine head unit allows iPod integration so the owner can enjoy his music library on the go, especially when that means blasting down the Wangan at 300+ km/h!
In a world where everyone seems to be consumed with the latest and greatest, it's inspiring to see just how well the RB-powered Skylines continue to raise the bar with the help of an experienced tuning venture. HKS is already working on a V-Cam system for the exhaust side of the RB26, as well as testing new generation high-pressure fuel systems, and more and more trends of today's newer engines and tuning continue to find their ways to these timeless engines. Kitabayashi-san won't disclose what the next project rolling out of the Pentroof garage and onto the Wangan will be, but you can bet we'll first in line to ride shotgun!
"The new build of Skyline/GT-R"
"high power engine constructor; high power wangan destroyer!"
BNR34 Skyline GT-R
Output: 680 HP @ 7,200 rpm; 506 lb/ft @ 5,800 rpm
Engine HKS 87mm forged pistons, H-beam connecting rods, valve springs, V Cam step 1 type B, 1.2mm metal head gasket, EX camshaft, adjustable EX cam pulley, compressor velocity stack, GT-R fuel pump, oil cooler, F-Con V Pro; Pentroof balanced crankshaft, fuel rail, head polishing, bronze valve guides; Nismo bearings, GT plenum, radiator cap, low-temp thermostat, oil catch tank; Trust extended oil pan, T78-33D turbo, front pipe, external wastegate, Ti-R titanium exhaust system, piping kit, intercooler, heat insulation, racing plugs, aluminium radiator; Sard fuel pressure regulator, 1,000 cc/min injectors, radiator hoses; Apex sports catalyst; JUN big-capacity oil pump; N1 water pump; ARC radiator shroud; K&N filter; Pentroof 45mm stainless steel exhaust manifold, custom white valve cover
Transmission ATS triple-plate carbon clutch, lightweight flywheel
Suspension & Brakes Ohlins PCV adjustable suspension; Cusco adjustable upper arms, pillow ball tension rods; Brembo monoblock six-piston front calipers,380mm two-piece slotted discs (front), four-piston Lotus rear calipers, 370mm two-piece slotted discs (rear); PFC racing brake pads; Nismo stainless steel brake lines
Wheels & Tires 18x9.5 Rays Engineering Volk Racing TE37 wheels; 265/35-18 Yokohama Advan Neova AD08 tires
Exterior Nismo Z-tune front bumper, front wide fenders, side skirts, rear skirts, R-tune dry carbon hood, GT LED taillights; Top Secret carbon fiber GT-wing
Interior Nismo 320 km/h meters, quick shifter, GT shift knob, Alcantara steering wheel; Takata MPH-341 racing harness
Electronics Nismo Version II MFD kit; HKS V-Cam controller; Trust Profec B Spec-II boost controller; Alpine CDE-9881 Ji CD head unit & iPod interface