What is up engine heads! Today it's time for the first ever boxer engine on Iconic engines!
And of course we're starting out with Subaru's mainstay engine, the EJ20 and EJ25 engines.

Although the Impreza made the EJ20 famous, the Legacy was the first car to have it. In 1989 Subaru introduced the first generation of the Legacy and with it the EJ20 engine, which was designed to replace the EA engine. Now the EA engine wasn't bad, but by 1989 it had become a bit ancient. The EA engine was introduced way back in 1966 to power the first ever front wheel drive Subaru car, the Subaru 1000, and from that point onward it powered more Subaru vehicles, most notably the Leone, the Brat and the 80s-tastic XT.

Unlike many manufacturers that first introduce low performance version of an engine and then upgrade it later in the production run the EJ20 was available in three versions from day 1 in the Legacy. A SOHC, a DOHC and a turbocharged DOHC engine, with pretty impressive hp numbers right from the start.
But in 1992 magic happened. Three letters combined to create something beautiful.
WRX. World Rally Experimental. In November of 1992 the first generation of the Subaru Impreza WRX debuted and with its turbo boxer, stiffened up suspension and symmetrical all wheel drive it brought rally inspired technology to the masses. In 1994 letter soup magic struck again. STI, Subaru tecnica international which further enhanced the WRX recipe with even more rally awesomeness. The EJ20 engines in the STI Imprezas churned an impressive 250 horsepower from the 2.0 blueprinted engines. Each of these engines received special attention and dedicated tuning which is why only one hundred of these were made per month back in 1994.
Just 1 year later Subaru proved that it had a winning recipe because in 1995 the EJ20 engines in the rally prepped Imprezas took both the Driver's and manufacturer's championship titles in the Wolrd Rally Championship, bringing these cars international fame. Subaru would take the both titles two more times, cementing it's dominance in World Rally before withdrawing from WRC in 2008.
In 1994 the larger 2.5 liter EJ25 enters the scene in Japan and by 1996 it was on the US market. Designed to respond to the instant torque needs of the American consumer the larger EJ25 started life in the Legacy and the Outback but spread quickly to power the majority of Subaru's vehicles including the Impreza, the Forester and the Baja. Starting with 2004 the larger EJ took over as the engine of choice for both the WRX and STI imprezzas (not in Japan) as well as the high performance versions of the Legacy, Forester and the Outback.
But did you know that an EJ engine also powered a SAAB? Yup, in 2005 the Saab 9-2x was introduced to the US market and as you can see it's not really a SAAB but a rebadged version of the Imprezza. Here's something else you might not know, and that's that the EJ20 engine existed in twin turbo form. From 1994 to 2005 Subaru installed twin turbo ej20s into Japanese Legacys and Australian Liberties.

All EJ engines can be divided into two phases.
Phase I: EJ15E, EJ15J, EJ16E, EJ18E, 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
Phase 1 covers fron 89 to 98 and Phase 2 from 99 and onward.
When it comes to the engine block all ej engines feature aluminum blocks with cast iron liners and aluminum heads. The EJ engines are an extremely rare example of an engine that can be found with a closed deck, and open deck and a semi open deck block. Early turbocharged ej20g engines produced until mid 1994 featured a closed deck with oil squirters for the underside of the piston. These are pretty rare nowadays. Starting with 1995 open deck block engines appeared and stayed in use for some naturally aspirated and ej205 equipped WRX, but starting with 2001 the vast majority of turbo ej engines feature semi-closed decks.
Compression Ratio: 9.5:1 - 10:1 (9.5:1 - 10.7:1 JDM) Naturally Aspirated
Compression Ratio: 8.0:1 - 9.5:1 Turbo
The block castings for EJ20 and 25 engines are virtually the same despite their different displacement. The EJ25 achieves greater stroke by using a different crankshaft and bored out blocks but uses the same length connecting rods as the EJ20 engines. This results in a different rod ratio between EJ20 AND 25 engines.

The tuning aspect of the EJ engines is unfortunately filled with misconceptions that refuse to go away and resulted in a reputation of weakness. Fact is that the vast majority of EJ engine failures isn't due to design, but due to the wrong tuning or the wrong parts. People with actual know-how build these engines to well over 1000hp today.

A special thank you to my patrons:
Daniel
Peter Della Flora

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