By now, you've surely heard all the news about the upcoming CBA-R35 GT-R. You know it has a 3.8-liter twin-turbo V6, 473bhp and 434lb-ft of torque, a rear-mounted twin-clutch transmission, Brembo brakes, Bilstein suspension, sticky tires and that it's going to be released in the US sometime next year. You've been bombarded with pictures, websites, articles and videos. No doubt, just 28 pages ago in this very magazine, you read that it'll sprint from zero to 60mph in 3.5 seconds and run the quarter in the 11s. But how will the GT-R fare when it goes on sale and the aftermarket gets its hands on it?
Engine
The recipe for Nissan's flagship supercar starts with the engine, the VR38DETT. According to GT-R chief vehicle engineer, Kazutoshi Mizuno, there are three conditions for a vehicle to be considered a modern supercar: a power-to-weight ratio close to 8lb/hp, a 186mph top speed and a Nrburgring lap time below eight minutes.
Naturally, horsepower is a necessary requirement and the GT-R comes on strong with two IHI turbochargers, connected to an all-new 3.8-liter V6 engine. According to Hiroyuki Ichikawa (from Nissan's Powertrain Engineering Division), the all-aluminum VR38 is based loosely on the VQ-series, but is different in almost every way. The casting is completely new, and the fully closed-deck unit uses plasma-coated cylinder bores to balance strength and weight. The VR uses twin throttle bodies ( la VQ35HR) and a single mass airflow sensor to meter air, which should help keep things simple on the ECU tuning side. What won't help is the drive-by-wire system controlling both throttle bodies.
The VR38 also uses a magnesium oil pan, which holds GT-R-specific Mobil One 0W-40 oil and Nissan's new wet/dry sump oiling system. Ichikawa tells us a dry sump-style oil pump, bolted inside the oil pan, sucks hot oil from each turbocharger and then, instead of feeding into a reservoir, spits the oil directly onto the standard wet sump oil pickup. From there, oil is pushed through an external cooler kit and then through the engine. The system has proved itself capable of maintaining proper oil pressure at up to 1.6g, according to Ichikawa-although he had no comment on its ability to fit onto a VQ35 engine.
The turbochargers' turbine housings are, unfortunately, cast as one piece, with the exhaust manifolds for each bank. The turbos use proprietary bolt-on housings to connect to the air intake tubing and to twin front-mounted air-to-air intercoolers. They're fairly small snails and the runners in each exhaust manifold are also quite tiny. Surely a compromise for throttle response and lag, this integrated system means that the only option for an upgraded turbocharger would be a complete replacement of the entire twin-turbo system. No, that's not going to be cheap at all.
However, the twin intercoolers should be kept on all bolt-on equipped GT-Rs, as it will be fairly difficult to fabricate any tubing shorter or smoother within the tight confines of the GT-R's engine bay. Replacing some rubber factory connectors with hard piping could be good insurance at higher boost levels, though.
From the turbos, each downpipe snakes under the car, joins into a single pipe after the close-coupled catalytic converters and resonators, then splits again into the twin-exit, quad-tipped exhaust. Precious pounds can easily be shaved here. And power gained-from going to a larger-diameter, lightweight single exhaust system made of thin-walled stainless steel or titanium.
Boost controllers, exhausts, air intakes and even turbo kits should be no problem, but if you're going to attempt anything beyond a bolt-on part, be careful who you choose to build your engine. Each VR38DETT will be hand-assembled by a single technician in an engine clean room, to exacting tolerances that will be easier to corrupt than improve upon.