[CLICK HERE TO SEE VIDEO OF THE 370Z ON TRACK.]
With power production out of the way, Costa and Dai enlisted the help of suspension guru Mike Kojima of MotoIQ.com in setting up the footworks. And here's where the Topple game that is setting up a track car is played; nail the proper relationship of wheel sizing/spring rate/damper valving/sway bar/suspension geometry/alignment, and you'll be the envy of your peers. Miss any one of these and your dreams of track dominance-along with your sanity-will likely come crashing down. Costa and the crew started with the wheels; more grip means more rubber, and if that rubber can be pushed out toward a car's fenders, the added girth will decrease roll. The downside is that doing so will also throw off scrub radii and increase camber gain, but with the adjustable upper control arms from SPL, along with a host of custom-fabricated bits from Costa, most of the drawbacks were negated. "Another problem point was the amount of anti-squat and anti-dive the 350Z has from the factory," explains Kojima. Without getting too technical, anti-squat is a mechanic of the car's control arms that allows more compression of its springs as squat increases, allowing progressive, low-rate springs to be used for increased comfort in daily driving, which compress and stiffen under load from cornering and acceleration. Anti-dive is the same as it applies to the front, under braking. While both are great for stock, street-driven cars, once suspension geometries are modified by lowering a vehicle, and springs are swapped for stiffer, linear replacements (like the 12/14kg/mm front/rear KW coilovers added by the GTI crew), it causes binding and traction loss when it's most needed. The custom bits fabbed up for the 370Z allowed some reduction of these features, "but looking forward, there's a lot more we can do with it, if we decide to switch to Limited class," explains Kojima.
A 32mm Whiteline front and 20mm rear sway bar were also added to further uninhibit squat and unload springs during cornering, while SPL rear spherical bushings and aluminum differential mount bushings, and Whiteline rear subframe bushings, allow the springs and dampers to work free from interference. "Rubber bushings flex and absorb more than urethane or aluminum," explains Costa, "which sacrifices the functionality of suspension components for comfort."
370Z
Unlike the 350Z, with its near decade of tuning experience and aftermarket support, the 370Z is an all-new beast. It looks similar to the 350, has a VQ-coded engine and Z badging, but for mechanical intents and purposes, that's where the similarities end. Ours, splayed across these pages, is also on long-term loan from Nissan, contributed so that we, Tein, and Greddy (along with help from Mackin Industries, Falken, Sunline Racing, Spec Clutch, Tees USA, and G-Dimension) could build it for the 2009 SEMA show. On paper, its track debut at Super Lap Battle was to be icing on the cake . . . but ask anyone involved with the project, and that's what we were really after.
Greddy was first to take a crack at it, and over the course of four months from within the confines of their U.S. headquarters in Irvine, CA, used the Z34 to prototype new versions of their Ti-C exhaust system and Tuner Turbo Kit. Consisting of two TD06SH-20G turbos, cast steel manifolds, external wastegates, downpipes, dump tubes, Airinix intakes, intercooler piping, and a Type 29 front-mount intercooler, once tuned with the optional (so as to leave fuel management options open) E-Manage Ultimate and 440cc injectors, low(ish) boost tuning netted 449.5 whp and 344.6 lb-ft of torque on 91-octane pump gas. The Greddy crew speculates up to 850 whp can be had with race gas and proper tuning, and 450 whp with their optional upgraded fuel system we opted for-perfect for a track-prepped street car.