The 2011 Forester first gets the all-new mill, with the Impreza, Legacy, and Outback to follow, perhaps for 2012.
Although Subaru's current 'boxer' four has been updated nearly every year with small but significant improvements, the engine dates back to 1989, and the original introduction of the Legacy. Originally the engine was used in 2.2-liter form in the U.S. market (and 1.8- and 2.0-liter versions were quite common in other markets) but over the past ten years or so Subaru has exclusively (on non-turbo models) using 2.5-liter versions.
The new engine, according to Automotive News, will range from 2.0 to 2.5 liters and will, in some variations, get both direct injection and a start-stop system—as well, of course, as turbocharging in sportier models like the Impreza WRX and STI. Although we can't say for sure, it's likely that the naturally aspirated versions would be considerably more powerful.
And according to Subaru, it gets a lower-maintenance timing chain system, instead of timing belts.
Subaru is in the process of introducing a new, proprietary-design CVT automatic across its four-cylinder product line—as it already has in the 2010 Subaru Legacy and Outback—replacing the old four-speed auto. However, as a company official recently told The Car Connection, the new transmission doesn't fit as easily with the current configuration of the Impreza and Forester. The company, with limited engineering resources, could well simply be waiting to deploy the CVT with the new engine.