Subaru uses a four or five character code to identify all of their engines. As of August 2022 these are the engines presently in models sold by Subaru FB20D: 1995 cc DOHC, 2017+ Subaru Impreza, and 2018+ Subaru Crosstrek FB25D: 2498 cc DOHC, 2019+ North American Subaru Forester, 2020+ North American Subaru Legacy, 2020+ North American Subaru Outback, and 2021+ North American Subaru Crosstrek 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. 2021+ USDM Subaru WRX CB18: 1795 cc DOHC, 2020 JDM Subaru Levorg, 2021 JDM Subaru Forester

Two-cylinder

Subaru EK engine

The EK series was an inline twin cylinder engine. Early versions were air-cooled two-stroke cycle, later replaced with water-cooled configurations in 1971. The engine was upgraded to a four-stroke SOHC in 1973 to meet Japanese Government emission regulations, using the SEEC emissions system (later SEEC-T), with an alloy block and head.

The () was used from 1958 until 1989 in most Kei car models.

+ Subaru EK engine summaryCoolingStrokeName Displacement Bore × Stroke Output Compression Ratio Applications Air Two EK31 at 4,500 rpm – 6.5:1 Subaru 360 (1958–68)Sambar (1961–70) at 4,700 rpm – at 5,000 rpm – EK51 at 5,000 rpm Subaru 450 (MAIA) Japan & North America (1960–66) EK32 at 5,500 rpm – 7.5:1 Subaru 360 and 360 Young SS (1968-70) at 7,000 rpm – EK33 at 5,800 rpm R-2 Van K41, Sambar K55/K64 6.5:1 Subaru R-2 (1969–71)Subaru Sambar (1970–73) at 6,500 rpm R-2 at 7,000 rpm R-2 SS 7.5:1 at 6,500 rpm R-2 Sport Edition Water EK34 at 5,500 rpm Sambar K71/K72/K81 6.5:1 Subaru R-2 1971.10-1972.07Subaru Rex 1972.07-1973.10Subaru Sambar 1973.02-1976.02 at 6,000 rpm R-2, Rex at 6,500 rpm Rex TS at 7,000 rpm R-2 GSS at 6,500 rpm Rex GSR Four EK21 at 8,000 rpm Rex 73.10-75.12 9.5:1 Subaru Rex K22 1973.10–1976.05Subaru Sambar 1976.02–1976.05 at 7,500 rpm Rex Van K42, Wagon K26, Rex sedan 75.12-76.05 EK22 Rex 5 Van K43, Sambar 5 K75/76/85 9.0:1 Subaru Rex 1976.05–1977.05Subaru Sambar 5 1976.05–1977.03 at 6,500 rpm Rex 5 K23 EK23 (2V) at 6,200 rpm Rex 8.5:1 Subaru Rex (1977.05–1989)Subaru Sambar (1977–90) at 6,200 rpm Rex Van, Sambar at 6,000 rpm Rex 2nd gen & Rex Combi at 6,000 rpm Rex 3rd gen EK23 (3V) at 6,000 rpm Sambar 9.0:1 Subaru Rex Viki (1986–89)Subaru Sambar (1989–90) at 7,000 rpm Rex EK23 (2V-T) at 6,000 rpm 8.5:1 Subaru Rex Combi (1983–86) EK23 (3V) at 7,000 rpm 9.0:1 Subaru Rex VX (1986–89) EK23 (SC) at 6,400 rpm Subaru Rex Supercharger (1988–89) EK42 700 9.5:1 Subaru Rex and Sambar/700 (export only, 1982–89) at 6,400 rpm low octane version at 6,400 rpm M70, Mini Jumbo, Sherpa (high octane version)

Notes

Three-cylinder The EF series engine is a liquid-cooled three-cylinder, four-stroke, with SOHC. It is not compliant with Japanese Government regulations concerning displacement of kei cars with a current maximum limit of 660 cc. The EF appeared while the EK was being replaced by the EN05.

Subaru EF engine EF10: Bore x Stroke mm = 78.0 x 69.6 Piston displacement = 997 cc Compression ratio = 9.5:1 Two valves per cylinder SOHC 2V, 55 hp at 5,200 rpm 1984–1987 Subaru Justy EF12:Bore x Stroke mm = 78.0 x 83.0 Piston displacement = 1189 cc Compression ratio = 9.1:1 Three valves per cylinder SOHC 3V, 66-73 hp 1987–1994 Subaru Justy

Four-cylinder 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. The engine has a total displacement of from a square bore x stroke with a compression ratio of 16.3:1 and uses five main bearings. The EE20 shares a bore pitch dimension and assembly line with the EZ30 at the Ooizumi Factory; compared to the contemporaneous gasoline EJ20, which has a similar displacement, the EE20 is shorter.

The common rail solenoid injector is manufactured by Denso and operates at . The IHI variable geometry turbo is mounted under the right side of the engine, close to the exhaust manifold, reducing turbo lag. For the Legacy 2.0D, Subaru claimed consumption improved by 15 to 20% (ranging from ) and that emissions fell from compared to the similar model with a gasoline engine.

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. Details about the engine were first released in February 2008, 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. The compliance was soon updated to Euro-5 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. In September 2008, FHI announced the EE20 would be available as a slightly modified variant (the diesel particulate filter was now closed) in Forester and Impreza models sold in Europe starting that fall. For the Forester, output was reduced slightly to .

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.Subaru Technical Journal, No. 34 published in June 2007Subaru Technical Journal, No. 33 issue published in June, 2006

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