Powertrain; Piston - Subaru Legacy 2015 Technicians Reference Booklet

2015 Legacy and Outback

Powertrain

FB 2.5
The 175-horsepower/ 174 lb-ft torque 4-cylinder FB 2.5 engine for the 2015 Legacy and Outback
emphasizes manageability in practical use with enhanced medium and low-speed torque. The
engine has been refined focusing on the air intake and exhaust systems. Engine quality has been
enhanced with measures against noise and vibration, weight reduction, and simplification. The
basic casting thickness of the cylinder block was decreased from 3.5 mm to 3.2 mm to reduce
weight while maintaining rigidity.

Piston

The crown surface of the piston has been raised increasing compression from 10.0 to 10.3. The
center of gravity and skirt shape have been changed to reduce vibration. Sliding friction has
been reduced by the application of a new coating on the piston skirts. A new PVD (physical vapor
deposition) coating process is used for top compression and oil control rings to aid in abrasion
resistance. Piston ring tension has been decreased to reduce friction and improve fuel economy.
Note: Engine oil and filter replacement for all 2015MY vehicles has been reduced to
6000 miles. The excessive oil consumption rate in the Owner's Manual remains
at 1 quart every 1,200 miles. Always consult the latest Oil Consumption Test
procedures listed on Subarunet for updated information.
FB 2.5 Engine
Optimized center
of gravity
Optimized skirt shape
Redesigned FB 2.5 Piston
154
New Technology Training
10-1
Raised crown surface
10-2
(Module 926)
June 2014