The S2000 is not for everyone. You have to like two-seater convertibles and be man enough to endure the accompanying hairdresser jokes. The S2000 is also a Honda, so it's powered by an engine shriller than a banshee's mother-in-law. Although universally regarded as one of the finest naturally aspirated four-cylinder engines available, the S2000's F20C is loved and despised because of the way it makes power-high up in the revs, in a narrow band before redline. While admirers love the free-spinning nature that demands constant shifting of the fantastic six-speed gearbox, detractors simply want more power and torque. And they want it earlier.
Like a few other performance dealers, GReddy has addressed the concerns of the latter through forced induction. A new, comprehensive TZ Turbo Kit for the Honda S2000 (AP2) is centered around a single Mitsubishi T518Z internally wastegated-style turbocharger. In GReddy-ish, a T518Z is essentially a compact 18G compressor connected to a TD05 turbine with 10 cm2 on a T28 footprint. The kit comes complete with all the parts seen in the photo below, including a V-spec polished front-mount intercooler with cast end tanks, upgraded fuel pump and 550cc/min injectors, turbo downpipe with divorced wastegate piping, wiring harness, and preprogrammed E-manage ECU. Early production units are shipping with a TIG-welded tubular stainless steel manifold, although the company plans on switching to a more durable cast-iron piece, depending on demand. The advantage of a tubular manifold is the semi-equal-length and compact short runner designs allowed by the placement of the engine.
GReddy claims the kit is good for 305hp at the crank on 8psi of boost: an increase of 68hp over the stock car. To evaluate those claims, we brought a stock, low-mileage AP2 S2000 to our dyno, running back-to-back against a GReddy-equipped model.
For some reason, our stock S2000 showed an abnormally high power and torque output of 216 wheel-hp and 151lb-ft-far more power to the wheels than expected from an engine rated at 237 crank-hp.
GReddy's test car put down 286 wheel-hp at 7.5 to 8psi of boost. At high boost, the kit just makes it into the 300hp club, with 228lb-ft of torque. That's a 72hp increase at the wheels near rev-cut. Most importantly, the turbo (controlled by a PRofec B Spec II boost controller) reaches peak boost around 3500rpm and posts a peak gain in torque of 66lb-ft at 4000rpm under low boost. Crank it up to 9.5psi on high boost and the gain is 95lb-ft at the same rpm. Just what every S2000 needs-gobs of axle-twisting goodness.
At first glance, this is an impressive kit. GReddy has covered all the bases. Not only is all the piping and hardware included, so are trick bits like an oil filter relocation kit, aluminum panels to direct hot radiator air away from the engine bay, and ducting to supply fresh air to the new open-element filter. The turbo is also tucked low in the engine bay for more cooling air at speed. Only minor modifications to the stock hardware are required, like trimming the exhaust manifold's heat shield, so the new pressurized polished piping has sufficient clearance. Some vacuum couplings and the MAP sensor also need relocating.
The only flaws we've seen are signs of heat soak at high revs as the ECU starts pulling ignition timing, resulting in a slightly rough power curve. But this is on a dyno with the fan barely able to push fresh air into the front-mount intercooler (neatly tucked deep within the bumper). On the road, this shouldn't be a problem.
In response to installation difficulties with earlier AP1 S2000 kits, GReddy has simplified the AP2 kit with upgrades including banjo bolts and a plug 'n' play harness that makes wiring a snap. Installing the full kit should take the average home mechanic about eight hours.
GReddy's TZ turbo kit for the Honda S2000 (AP2) is available now for $5599 (MSRP) and a street price of around $4700.