There’s nothing surprising about a power figure as high as 1,200 hp, especially in the world of GT-Rs. The previous generation, powered by the legendary RB26 motor, was always a favorite among drag racers who achieved 1,000+ hp by bolting on a big single turbo or adequately sized twin-turbo setups. While those cars managed to achieve such high power figures from a relatively low capacity of 2.7 liters and up, depending on bottom-end modifications, responsiveness and reliability were hardly their forte; a powerband of about 2000–3000 rpm was all you could hope for. However, with the introduction of the R35 a few years back, things have changed quite a lot. With 3,800cc of capacity, the VR38 engine has increased tuning potential tenfold, and with it introduces a very different type of character. While the R35 might be well suited for straight-line performance — thanks to its AWD system and lightning-quick dual-clutch transmission — it’s in the time attack scene where this car is beginning to shine. There’s no better extreme example of such a vehicle than the Trust (or GReddy, as we know them in the U.S.) GT-R R35RX.
Trust has taken on longtime rivals in the Japanese tuning world, HKS, at their own game. Trust was the first to come up with a turbo kit for the VR38 a couple of years back, a specially matched TD06 setup that would easily allow the large-capacity V-6 to churn out 800 hp. HKS then stepped it up with its own R35 development car that with an all-new GT800-plus kit managed an impressive 1:45 lap around Fuji Speedway (on slick tires).
The next move was Trust’s, and the company hit the drawing board by planning the ultimate setup for the GT-R, something that would prove the potential for power and reliability. With plenty of development and testing having been carried out by GReddy USA on the GR43 stroker kit, the next step for Trust in Japan was to push the limits and begin yet another development program to extract as much power as possible. So with a bulletproof bottom end made up of the RX43 specially treated and sleeved engine block, forged and balanced crankshaft, H-section connecting rods and oversized pistons, the real work began. A lofty goal of 1,200 hp was set, an extra 300 hp over the 900 hp GReddy’s U.S. demo car was making. This called for bigger turbochargers, which came in the form of externally gated RX1200 prototype items. When run at their 30-psi limit, these snails can flow a tremendous amount of air, which meant many other parts had to be redesigned. Larger-diameter RX35 intake and intercooler piping was developed, but there was no way the stock throttles and plenum were going to handle that volume of air. Enter the RX throttles, beautiful items built in anodized billet aluminum and featuring faster-reacting motors for better response. These feed the RX plenum, a large-capacity intake manifold that can easily cope with serious boost and feed the GR43 all the air it needs. A lot of port and polish work was done on the cylinder heads, fine-tuning flow potential and increasing volume. A complete valvetrain upgrade was next, consisting of larger-diameter valves, shims and springs with a set of GReddy 272-degree duration camshafts fitted for both the intake and exhaust sides.
Not surprisingly, 4.3 liters and 30 psi of boost require a serious amount of fuel, so six 1,000-cc/min injectors are mounted along the GReddy billet fuel rail to quench this thirst; a pair of racing fuel pumps and an adjustable fuel pressure regulator finish things off, while the GReddy e-Manage Ultimate piggyback ECU takes care of the engine management. The figures speak for themselves: 1,206 hp and a tractor-rivaling 1,085 ft-lbs of torque. Looking at the power and torque curves, it’s outstanding that there seems to be almost no loss of response, with the engine remaining explosive through the entire rev range — just what you need on a time attack car. Obviously, a setup like this suits larger circuits like Fuji and preliminary tests have shattered previously tuned R35 top speeds at the famed Japanese circuit with the car hitting 202.5 mph on the long straight with Tarzan Yamada at the wheel.
But how about the transmission? Can Nissan’s GR6 dual-clutch transaxle cope with these kinds of figures? The simple answer is no, so Trust has also made sure that things remain as reliable as possible along the driveline. GReddy upgraded clutch packs keep slip in check, while a Dodson first gear cog avoids potential failures. Despite being water- and oil-cooled, the GR6 suffers from extremely high temperatures on track, so GReddy has fitted a transmission cooler and a billet, larger-capacity oil pan kit take care of this.