Kyle's Corner (FYI) Subaru Updates Its 21 Year-old Boxer Engine

Subaru and Porsche have both been known for their flat horizontally opposed engines. Rumor has it that many years ago, Subaru actually copied the Porsche engine design.

And now Subaru has redesigned its flat four-cylinder boxer engine as a third-generation unit code named 'FB' rather than the previous "EJ.' The automaker made the engine update to better comply with future emission and fuel economy regulations. Of note is that the new FB engine is part of the 2011 Subaru Forester in the U.S. It will be used in the Outback beginning in 2012.

The old second-generation EJ engines powered Subarus all the way back until the 1989 Legacy. Thus, we can expect the new engine will likely be around for some time! The third-generation engines continue to displace 2.0 (FB20) and 2.5-liters (FB25).

The redesigned engine has a 15 mm longer stroke, an 8 mm smaller bore and a more compact combustion chamber compared to the outgoing engine. These engine changes are reported to improve fuel economy by 10 percent, increase low and mid-range torque, and improve emissions.

Additional updates to the engine involve a chain driven (rather than the past belt driven) valve train and a redesigned cylinder block and cylinder head. Furthermore, the engine is equipped with lighter pistons and connecting rods and an increased compression ratio at 10.5:1, up from 10.2:1. Last, but not least, the engine will have a cooled exhaust gas recirculation system and variable valve timing on both the intake and exhaust sides.

The new engine is reported to be smoother up the rev range than the engine it replaces.

Additionally, the fuel economy is expected to be about 35 mpg on the highway with lower emissions. This is not too bad for an all-wheel drive crossover such as the Forester.

The 2011 Subaru Forester came in 4^th out of a nine crossover comparison reported in USA Today. The addition of the new FB engine and a new transmission should lift the Subaru Forester nearer to the top of the pack.

Kyle Busch is the author of "Drive the Best for the Price..." He welcomes your comments or car questions at his auto web site: DriveTheBestBook.com . Follow Kyle on Facebook and Twitter.