GReddy's Mike Chung reassured me that his coworker wouldn't mind my positioning his turbo S2000's tach needle somewhere in the neighborhood of nine grand. At over 10 pounds of boost. On a local stretch of road just around the corner from GReddy's suburban headquarters. In the middle of the day. At first I thought maybe Mike didn't care for the guy. But I soon realized there were two more likely explanations. One: GReddy's S2000 turbo kit does little in terms of sacrificing Honda reliability and as such makes no qualms when it comes to revving the F-series full song. And two: visiting the upper part of the tachometer is a definite prerequisite for feeling all of what the T518Z turbocharger is worth.
Own an AP1 or AP2 S2000? Here're seven reasons why you should, at the very least, consider GReddy's newest Honda turbo kit.
The Engine
Honda should be commended for developing the F20C/F22C S2000 engine. It is, after all, the most powerful Honda four-cylinder we can get our hands on from the dealer. And it should be, seeing as how the whole point of the S2000 was of a celebratory nature, recognizing Honda's half-century of efforts. Horsepower per liter figures and the engines' engineering are both exceptional. Even the smaller F20C pushes 240 hp and 153 lb-ft of torque, and has an 11.0:1 compression ratio and factory forged pistons, a rarity in terms of Hondas. Sure, a respectable engine, but it always falls short when compared to turbocharged 4G63s and Boxers of smaller displacement making more power. Fortunately that can be taken care of.
The Turbo
GReddy's S2000 turbo kit is based off of a Mitsubishi Heavy Industries (MHI) manufactured TD05H-18G turbocharger, the compact T518Z. A couple of turbine housings are offered for this turbo, 8cm2 and 10cm2. The 2.0L, F20C and 2.2L, F22C both benefit from the 10cm2 exhaust housing's larger scroll area and inlet. The larger housing makes for a negligible amount of low-end lag but makes up for it in its ability to ultimately outflow the smaller housing, something you'll appreciate once the boost is turned well past 10 psi and backpressure becomes more of an issue. Boost is controlled by a 7psi internal wastegate. This speeds up installation time and allows everything to fit within the confines of the engine bay; the longitudinally mounted F-series affords little room on the exhaust side. Like all MHI turbochargers, the GReddy-spec T518Z has one of the most durable center cartridges available, featuring a large-diameter center shaft and free-floating bushings. Such bearing designs have been shown to outlast even some of the lower end ball bearing housings not to mention most other journal bearing cartridges. The compressor wheel measures in with a 50.5mm inducer and 68mm exducer, translating into a 55.1 trim piece. The turbine's 76.87 trim comes from a 56mm inducer and 49.1mm exducer. This means that the T518Z is good for roughly 420 hp when matched with either of the F engines. Of course, upgraded internals and proper tuning will be necessary at that point.