Good Things Come in Small Packages

 

4/8/2016

Version 13.1

The 2.0-Liter Direct-Injection Turbo SUBARU BOXER Engine

In the past, an automaker would build a high-performance vehicle by installing a larger-displacement engine. But the price for that power infusion was typically more weight, degraded handling, and higher fuel consumption.

Subaru never subscribed to the “bigger is better” philosophy and has always sought higher performance through careful powertrain and vehicle optimization. 

The 2002 Subaru Impreza WRX offered a 2.0-liter 4-cylinder turbocharged SUBARU BOXER engine for the U.S. market. Rally-bred, and packing a 227-horsepower punch, the vehicle proved wildly popular. In 2006, the WRX switched to a 2.5-liter engine, delivering 230 horsepower. For the 2009 model year, the WRX gained a significant horsepower boost, to 265, still with the 2.5-liter engine. That EJ series engine ended its run with the 2014 WRX but continues in the WRX STI.

The 2015 WRX brought an increase of 3 horsepower and 14 lb-ft of torque. Those numbers seem comparatively small at first glance, but a closer look reveals that Subaru achieved those gains with a smaller-displacement engine that consumed less fuel and reduced carbon emissions. 

A New Approach to Turbocharging

Subaru raised the bar yet again with the turbocharged version in the 2014 Forester XT, which generated 250 horsepower and 258 lb-ft of torque. This engine featured a combination of direct fuel injection, high compression (10.6:1), Subaru Dual Active Valve Control System (DAVCS), twin-scroll turbocharger, and intercooler to deliver both outstanding performance and better fuel efficiency than the 2.5-liter turbo it replaced. The cylinder-cooling effect of direct injection is key to allowing the high compression, which in turn is crucial for providing quick off-the-line response.

                                                                                                                                                                                                               

Vehicle Series Redline Horsepower Peak Torque PSI Max Turbo Boost
2014 WRX EJ series 6,500 rpm 265 244 lb-ft 14.2
2015-2016 WRX FA series 6,700 rpm 268 @ 5,600 rpm 258 lb-ft (from 2,000 to 5,200 rpm) 15.9
2015-2016 WRX with CVT FA series 6,500 rpm 268 @ 5,600 rpm 258 lb-ft (from 2,000 to 5,200 rpm) 15.9
2014-2016 Forester 2.0 XT FA series 6,000 rpm 268 @ 5,600 rpm 258 lb-ft (from 2,000 to 4,800 rpm) 17.1

 

Pushing the Performance Envelope

Subaru aimed even higher for the 2015 WRX. So they just cranked up the turbo boost, right? Wrong. The 2.0 turbo SUBARU BOXER in the WRX actually uses lower maximum boost than the Forester XT. In the WRX version, different camshafts and higher-rate valve springs, among other enhancements, push the performance envelope even further.
 
More efficient and more powerful than ever, the 2.0 direct-injection turbo SUBARU BOXER engine shows it pays to think small(er).