Subaru 2005 User Manual

Page 15

Subaru Boxer Engine

SUBARU, 1966

Subaru introduces the company’s trademark Subaru Boxer engine.

Impreza Engines
2.5 RS and Outback Sport: 2.5-liter 4-cylinder; 165 hp,
166 lb.-ft. of torque

WRX: 2.0-liter Turbocharged 4-cylinder; 227 hp,
217 lb.-ft. of torque

WRX STi: 2.5-liter Turbocharged 4-cylinder; 300 hp,
300 lb.-ft. of torque

UNDER THE HOOD,

what sets Subaru apart is the distinctively

innovative

, horizontally opposed Subaru

Boxer engine. It is available in Impreza models as a

powerful

300-hp intercooled and turbocharged

4-cylinder, a rally-bred 227-hp intercooled and turbocharged 4-cylinder, or a

robust 165-hp naturally aspirated 4-cylinder. Unlike conventional engine layouts, its

cylinders are aligned on a single, horizontal plane. This results in a powerplant

that is

compact

, lightweight and

well balanced

Now equipped with Electronic Throttle-Control

(ETC) drive-by-wire technology for more accurate

and precise response, the Subaru Boxer engine

delivers

outstanding

power and performance.

The compact size of

the Subaru Boxer engine
allows it to be placed
lower in the chassis,
reducing the vehicle’s
center-of-gravity for well-
balanced handling.

IMPREZA WRX STi.

Inside the ferocious Impreza WRX STi roars a sophisticated,

racing-inspired 2.5-liter Subaru Boxer engine. Its

advanced

block is cast of a specially

reinforced and remarkably lightweight aluminum alloy. Its molybdenum-coated pistons

help to reduce friction, while Dual Overhead Camshaft cylinder heads (DOHC) with hollow

camshafts further reduce mass for

quicker

engine

response. All of which is enhanced by a

high-boost

turbocharger producing 14.5 psi of maximum boost,

and a large intercooler with manual driver-controlled

water-spray to help keep the compressed intake air

cool and dense, resulting in increased horsepower.

Turbocharging the Subaru Boxer engine featured in

the WRX and WRX STi allows the benefit of increased
horsepower and torque without having to increase
engine size or displacement.

Our Active Valve Control System (AVCS) found on the

WRX STi helps to deliver increased low-end power while
allowing for greater breathing at higher engine speeds.