The Dyno

Baseline

As our previous T&T installations were performed on a different brand and type of dyno, the first order of business was to establish a new baseline number on HG Motorsports’ roller-type dynamometer (versus the hub-attached dyno previously utilized.) Here, Knose strapped the STI to the Dyno Dynamics’ rollers and registered 246.1 wheel horsepower with torque checking in at 275.2 lb-ft.

246.1 WHP @ 5,325 RPM
275.2 LB-FT TQ @ 3,747 RPM
Dyno Dynamics

Test 1 Crawford Performance FMIC

After tuning, the Crawford Performance front-mounted intercooler proved more efficient than the factory top-mount unit. In addition to lower intake-charge temperatures, the larger-diameter piping reduces airflow restriction, resulting in an overall 14.8 WHP increase.

260.9 WHP @ 5,397 RPM
283.6 LB-FT TQ @ 3,690 RPM

Test 2 GoFast Bit Pulley Kit

The GFB pulley kit revealed relatively large gains in both torque and horsepower throughout the entire powerband, particularly at this engine’s 3,500-to-3,600 RPM sweet spot. Peak wheel horsepower increased 5.3 whp while torque production improved by 14.2 lb-ft.

266.2 WHP @ 5,310 RPM
297.8 LB-FT TQ @ 3,672 RPM

Test 3 VP Racing Fuels MS109

The oxygenated, high-octane race fuel offered the greatest increase in power production while maintaining safe air/fuel ratios. Peak power increased 23.3 whp while torque rose by 20.3 lb-ft. Most of the greatest power gains generated by the EJ257 occur near the engine’s 3,600 RPM sweet spot.

289.5 WHP @ 5,371 RPM
318.1 LB-FT TQ @ 3,690 RPM

We brought our STI to the all-wheel drive Dyno Dynamics dynamometer at HG Motorsports in San Diego, California, for the final installation, testing and tuning. As our previous T&T installations were performed on a different brand and type of dyno, the first order of business was to establish a new baseline number on HG Motorsports’ roller-type dynamometer (versus the hub-attached dyno previously utilized.) Here, Knose strapped the STI to the Dyno Dynamics’ rollers and registered 246.1 wheel horsepower with torque checking in at 275.2 lb-ft.

The Crawford Performance FMIC kit was a relatively straightforward installation. The only modification required was to provision a charge pipe for a third-party bypass valve (not included in the kit.) Once the bypass valve was installed and plumbed, Knose rolled the STI back on the dyno for fuel and ignition map tuning. Even with several constant-speed fans providing the only airflow across the intercooler core, the kit was able to reduce temperatures enough to yield significant safe-margin gains after Knose’s tuning. Torque improved immediately at the low end, with gains as large as 30 lb-ft generated near 3,000 RPM. Power increases remained steady around 15-to-20 horsepower in the mid-to-upper regions of the powerband, tapering off just before the 6,750 redline. Peak horsepower checked out at 260.9 WHP.

Up next, Knose installed the GFB pulley kit on the EJ257 engine. Subaru designed the accessory belt system such that the belt driving the A/C compressor has to be removed to install the other driven belts and pulleys. After clearing this minor installation hiccup, Knose proceeded to refine fuel and ignition tables on the COBB AccessPORT with the STI back on the rollers. After tuning, the GFB pulley kit revealed a steady 5-to-6 horsepower increase from the sample start all the way through approximately 6,000 RPM. After that point, there was a slight 3-to-4 horsepower dropoff until the 6,750 RPM engine redline. Torque production saw a similar, immediate increase of about 7-to-8 lb-ft as low as 2,000 RPM, continuing up to the same 6,000 RPM drop-off point. There were minimal torque losses registered in the same 6,000-to-7,000 RPM range. At the end, peak horsepower increased 5.3 whp with gains as much as 8 whp in the middle range of the powerband.

With the hard parts in place and a nearly empty gas tank, we loaded the STI with 5 gallons of VP Racing Fuels MS109. With added insurance against detonation in the form of an oxygenated, high-octane fuel, Knose further refined the fuel and ignition maps with the COBB AP. As the EJ257’s factory turbocharger remained in place, the AccessPORT was used to contain boost at the previously maxed out 26psi boost level. Horsepower and torque gains were minimal in the lower RPM regions of the powerband, with power and torque increases manifesting above 3,000 RPM. By 3,600 RPM torque increased by over 20 lb-ft, with maximum torque gains coming in at almost 30 lb-ft at 4,500 RPM. Peak horsepower increased similarly across the powerband above 4,000 RPM, with peak wheel horsepower checking out at 289.5 WHP.