All of Subaru's four-cylinder engines (except the
EN series) are liquid-cooled, horizontally opposed
boxer four-strokes. ===
Subaru EA engine === The EA was used from 1966 until 1994 in most models. It is a basic two-valve-per-cylinder design with siamese ports, or one port that is directly next to another, and three main
crankshaft main bearings. Engines with
overhead camshafts were installed with two timing belts, whereas vehicles with overhead valves used timing gears exclusively. • EA52: 977 cc
OHV, 55 hp at 6,000 rpm used in the 1966–1971
Subaru 1000 • EA61: 1088.8 cc
OHV, 62 hp at 6,400 rpm used in the 1970–1972
Subaru FF-1 Star and
Subaru G • EA62: 1267.5 cc
OHV, 80 hp at 6,400 rpm used in the 1971–1972
Subaru G • EA63: 1362 cc
OHV, 58 hp at 5,200 rpm used in the 1973–1976
Subaru Leone • EA71: 1595 cc
OHV, 67 hp at 5,200 rpm or 68 at 4,800 rpm used in the 1976–1987
Subaru Leone and 1978–1980
Subaru BRAT/brumby • EA81: 1781 cc
OHV, 73 hp at 4,800 rpm used in the 1980–1984
Subaru Leone and 1981–1993
Subaru BRAT/brumby • EA81T: 1781 cc
OHV Turbo, 95 hp at 4,200 rpm used in the 1983–1984
Subaru Leone and
Subaru BRAT/brumby • EA82: 1791 cc
SOHC, 84-97 hp used in the
Subaru Leone and
Subaru XT • EA82T: 1791 cc
SOHC, 136 hp at 5200 rpm used in the
Subaru Leone and
Subaru XT Subaru EE engine (diesel) Subaru unveiled the world's first boxer
diesel engine to be fitted in a passenger car at the Geneva Auto Show in 2007. This 2.0L
DOHC engine, designated the EE20, has an output of at 3600 rpm and develops of torque at 1800 rpm, with a redline of 4750 rpm. Fuji Heavy Industries (FHI) spent three years starting in fall 2005 developing the EE20 after concluding the marque needed a diesel engine to compete in Europe. after an additional preview at
Frankfurt in 2007, and an official announcement of applications was made at
Geneva in March 2008. The EE20 was originally released with
Euro-4 emissions compliance; an
oxidation catalyst and
diesel particulate filter are mounted close to the turbo, using heat from exhaust gases, and the
exhaust gas recirculation system is water-cooled to meet regulations. and Euro-6 in 2015. ;Availability Per the March 2008 announcement at Geneva, the EE20 was sold in Legacy (wagon and sedan) and Outback vehicles for the European market; the diesel was only offered with a
manual transmission at first, and the
clutch and
flywheel were specifically modified for diesel use. The EE20 was offered with the Impreza XV at that model's launch in 2010. The Subaru
continuously variable transmission (branded
Lineartronic) was offered as an option for EE20-equipped Outback models starting in 2013, and sales of the Lineartronic EE20 Outback would start in Australia later in 2013. At Geneva 2013, the diesel boxer was combined with three electric motors to form the hybrid powertrain of the
Subaru VIZIV Concept. The Lineartronic EE20 powertrain was added to the Forester in 2015. In 2016, citing increasingly stringent emissions standards, the project manager for the Impreza stated that further development of the EE20 had been halted. In September 2017, Subaru announced production of diesel automobiles would end by 2020; at the time, sales were approximately 15,000 diesel-powered cars annually in Europe and Australia. The capacity gained would be used to start producing
plug-in hybrids in 2018 and electric vehicles by 2021. At Geneva in March 2018, Subaru UK confirmed its parent company's plans to discontinue diesel production, but had enough stock on hand to meet projected demand through the end of 2018. ===
Subaru EJ engine=== The EJ engine was introduced in the 1989
Subaru Legacy to replace the EA engines. It was designed from scratch with five main crankshaft bearings and four valves per cylinder and can be either
SOHC or
DOHC and one
timing belt. The fifth digit is the only way to tell without seeing the engine. • EJ15: 1483.4 cc
SOHC, 1990–2003 JDM
Subaru Impreza • EJ16: 90 hp at 5,600 rpm used in the 1993–2006
Subaru Impreza • EJ18: 1820 cc
SOHC 110 hp at 5,600 rpm used in the 1993–1996
Subaru Impreza and Euro and JDM
Subaru Legacy • EJ20: 1994.3 cc, available in Australia, Europe and Japan
naturally aspirated at 115–190 hp and with a
Turbo 220–280 hp used on Most Models, (2002–2005 WRX in the United States) • EJ22: 2212 cc, 135–280 hp used in the 1989–2001
Subaru Impreza and
Subaru Legacy • EJ25: 2457 cc, 165–320 hp found in Most Models 1995–2021 • EJ30: Special limited engine. Four were built by Subaru, but only 3 remain in working condition. There is no readily available technical or power information on these engines. Generally the EJ-series can be divided into two versions: the Phase I engines (1989–1998) and the Phase II engines (1999–2010). The Phase II engines featured new cylinder heads and crankshafts with the thrust bearing located at crank bearing #5 instead of #3. The designation also changed from Phase I to Phase II. All Phase I engines have an alphanumerical suffix behind the standard EJXX designation, all Phase II engines have a numerical suffix behind the EJXX designation. Example: Phase I: EJ15E, EJ15J, EJ16E, EJ18E, EJ20B, EJ20D, EJ20E, EJ20G, EJ20H, EJ20J, EJ20R, EJ20K, EJ22E, EJ221, EJ25D Phase II: EJ151, EJ161, EJ181, EJ201, EJ202, EJ203, EJ204, EJ205, EJ206, EJ207, EJ208, EJ222, EJ251, EJ252, EJ253, EJ254, EJ255, EJ257, EJ20X, EJ20Y • ''There's at least 3 exceptions from this rule - MY'07 EJ20F engine. Most likely F stands for bi-Fuel (engines prepared for LPG). This engine model has reinforced engine valves. This is unconfirmed info, based only on users' experience and observations. JDM Legacy GT EJ20X and EJ20Y engines are also exceptions.''
Subaru EL engine/Boxer type 3 The
() replaced the EJ15 and is used in the JDM Subaru Impreza 1.5R (series GD, GG, GE, GH) starting with model year 2006. It is based on the EJ engine and shares many components, like the crankshaft from the EJ25. It has DOHC cylinder heads with AVCS variable valve timing on the intake. • Displacement: 1,498 cc • bore x stroke: 77.7 x 79 mm • compression ratio: 10.1:1 • maximum horsepower: 110ps (81 kW) at 6,400 RPM • maximum torque: 14.7kgm (144Nm) at 3,200 rpm •
AVCS ===
Subaru EN engine=== The Subaru EN
inline-four engine was introduced in 1988 to replace the
straight-two EK series engine that was originally engineered as an air-cooled engine, then modified as a water-cooled engine used in the 1969–1972
Subaru R-2. The EN was used in all
kei cars and
kei trucks in production by Subaru up until 2012. ===
Subaru FA engine===
() The FA was developed from the FB engine, however, efforts to reduce weight while maintaining durability were the main goals of the FA engine. While the FA and FB engines share a common platform, the FA shares very little in dedicated parts with the FB engine, with a different block, head, connecting rods, and pistons. • FA20D: 1,998 cc
DOHC, aka
Toyota 4U-GSE; 2013-21
Subaru BRZ/Toyota 86 • FA20F: 1,998 cc
DOHC, turbo, 2012+ JDM
Subaru Legacy 2.0GT DIT and 2014+
Subaru Levorg; 2014+ USDM and JDM
Subaru Forester XT; 2015-21 USDM
Subaru WRX • FA24D: 2,387 cc
DOHC, 2022+
Subaru BRZ/Toyota 86 • FA24F: 2,387 cc
DOHC, turbo, 2019+ USDM
Subaru Ascent, 2020+
Subaru Legacy, and 2020+
Subaru Outback. 2022+ USDM
Subaru WRX ===
Subaru FB engine=== The FB-series (initially available as naturally aspirated engines in 2.5- and 2.0-litre displacements) is the first new generation of boxer engine since the EJ-series. Subaru announced details of the FB engine on 23 September 2010. By increasing piston stroke and decreasing piston bore, Subaru aimed to reduce emissions and improve fuel economy, while increasing and broadening torque output over the previous generation engine. The FB has an all-new block and head featuring dual overhead cams with intake and exhaust variable valve timing (AVCS - Active Valve Control System), and a timing chain that replaced the timing belt. Moving to chain-driven cams allows the valves to be placed at a more narrow angle to each other and shrinks the cylinder bore from 99.5 mm to 94. It results in less unburned fuel during cold start, thereby reducing emissions. Subaru also uses asymmetrical connecting rods like those in
EZ36. The FB is only marginally heavier and has similar exterior dimensions compared to an EJ engine of equivalent displacement. In Jan 2011,
Car and Driver was told direct injection would be added soon. Direct Injection was added to FB engines used in the 2017 Impreza, 2018 Crosstrek, 2019 Forester and the 2020 Legacy and Outback models. Subaru claims a 28-percent reduction in friction losses, mainly due to lighter pistons and connecting rods. The FB has a 10% improvement in fuel economy with the power coming on sooner and the torque band being broader. • FB16E: 1600 cc
DOHC, 2012+ EUDM
Subaru Impreza XV 1.6i • FB16F: 1600 cc
DOHC, turbo, 2014–20
Subaru Levorg • FB20B: 1995 cc
DOHC, 2011+ JDM
Subaru Forester, 2012-2016
Subaru Impreza, and 2012-2017
Subaru XV • FB20D: 1995 cc
DOHC, 2018+
Subaru Impreza, and 2018+
Subaru XV • FB20X: 1995 cc
DOHC, 2014–16
Subaru XV Hybrid • FB20V: 1995 cc
DOHC, 2019+
Subaru XV Hybrid • FB25B: 2498 cc
DOHC, 2011–18 North American
Subaru Forester, 2013-2019 North American
Subaru Legacy, and 2013-2019 North American
Subaru Outback • FB25D: 2498 cc
DOHC, 2020+ North American
Subaru Forester, 2020+ North American
Subaru Legacy, 2020+ North American
Subaru Outback, and 2021+ North American
Subaru XV ===
Subaru CB engine=== The
CB engine was first introduced in 2020 with the
second-generation Levorg. According to Subaru, CB stands for Concentration/Compact Boxer. The first engine in the series is designated
CB18, a 1.8 litre dual overhead cam 16-valve engine featuring dual
AVCS with
gasoline direct injection and a turbocharger. Bore and stroke are , respectively, and the compression ratio is 10.4:1. Rated output power is at 5,200–5,600 RPM and torque is at 1,600–3,600 RPM. Compared to the FB16 used in the previous generation of the Levorg, the CB18 offers decreased fuel consumption ( for the CB18 and for the FB16, both using the
JC08 mode) and increased torque ( for the CB18 and for the FB16). In addition, the CB16 achieves its peak torque at a lower engine speed. The CB18 also is shorter and lighter than the FB16; the bore pitch (centerline to centerline spacing between adjacent cylinders) has decreased from , the overall crank length has decreased from , and engine weight has been reduced by . For the first time in a Subaru engine, the centerlines of the cylinder bores do not intersect with the crankshaft axis to reduce friction during the piston downstroke; instead, there is a crank offset of . Overall
thermal efficiency is 40% due to the adoption of
lean-burn combustion with an
excess air ratio (λ) of 2. • CB18: 1795 cc
DOHC, 2020
Subaru Levorg, 2021
Subaru Forester ==Six-cylinder==