DOING IT HIMSELF
Chang bought himself a daily driver for work and began educating himself about the EJ257 engine. He started by printing and studying the Subaru Factory Service Manual. With a better understanding and knowledge of the engine, he tore down the block and took it to a machine shop to be machined. After double-checking the shop’s work, he took the block home and used a torque plate and a Sunnen hand hone to cut a crosshatch pattern on the cylinder walls that he was satisfied with to properly seal with the rings. Go with more Flow After blueprinting and assembling the shortblock with Manley pistons, rods and billet crankshaft, Chang got back to the books, learning about cylinder head work.
[pullquote]CHANG CONSTRUCTED A FLOW BENCH IN HIS GARAGE AND BEGAN PORTING CYLINDER HEADS[/pullquote]Examination of his cylinder heads afterwards disheartened him further, as he learned that he’d been charged a lot for valve lash adjustment, the valve seals weren’t installed properly and the valve seat runout was way out of tolerance. He took it upon himself to improve the volumetric efficiency of his cylinder heads. Chang constructed a flow bench in his garage and began hand porting cylinder heads. “I bought some junk cylinder heads off of eBay and started practicing with basic short side radius tricks. Eventually I got to a point where I had a balanced port job that I was happy with,” he said. Chang then invested in a variety of valve cutting tools, which he took to a local shop that had a Serdi valve seat machine. With his tools and instructions, the shop would then cut the valve seats under Chang’s supervision. The resulting custom valve job was then measured to ensure proper runout tolerance of 0.001-inch before a complete Manley valvetrain was installed in the heads.
BOOST TO BLAST
The now fortified EJ257 needed an efficient means of pressurizing the cylinders, so Chang selected a Precision Turbo & Engine PT6466 turbocharger for the duty. A FobiaFab exhaust manifold positions the turbocharger in place of the right fog light to provide a direct and unrestricted supply of air to the impeller. With an AEM EMS Series 2 engine management system regulating boost, fuel delivery and ignition timing, Chang put his hard-earned tuning knowledge to work. With E85 in the tank and peak boost pressure locked in at 30 psi, he adjusted the tables accordingly, recording 681 horsepower and 529 lb-ft of torque to the rollers of DSPORT’s Dynojet 424xLC2 AWD dynamometer.