For over three decades, the EJ20 was the workhorse of Subaru, as the 2.0-liter flat four boxer engine would power models throughout the brand’s lineup. However, it’s the engine’s generations of service under the hood of the brand’s World Rally eXperimental (WRX) models that gave it legendary status when it retired in 2019. With years of proven success in the World Rally Championship and an exhaust sound unlike any other, the engine became beloved by those in the tuning and rally crowd alike.
Today, the EJ remains fondly in the memories of Subie fans and is still the weapon of choice for amateur rally drivers, aftermarket tuners, and engine swappers worldwide. But with over 30 years of data, we’ve learned that it’s far from a perfect power plant. Its design has caused a plethora of problems, as has a certain part that’s grown infamous among owners worldwide. Let’s break it down.
The flat-four advantage
Introduced in 1989, the EJ family of motors replaced the long-serving EA family of flat-fours Subaru had been using since 1965. The engine layout has been a crucial part of the Subaru formula, and the brand has elected to go the way of the boxer for a multitude of reasons.
The engine’s moniker comes from its pistons’ unique motion. Unlike a traditional V-format engine, each piston has its own crankpin, meaning adjacent cylinders extend and retract at the same time, a setup that, when viewed at full speed, looks like a pair of boxers punching each other. This leads to a far better natural balance for the engine, as the pistons’ mirrored movement cancels out reciprocating forces, resulting in far lower vibration than the EJ’s inline-4 cousins.
Everyday commuters loved the engine’s low vibration, but enthusiasts would find even more benefits to the boxer. With its flat layout, the low placement of the boxer gives a lower center of mass, and increases overall handling capabilities. This keeps boxer-equipped cars stable and agile, and when paired with Subaru’s all-wheel drive, transforms the engine into a weapon on rally stages.
Rally heritage
The EJ would be first used in motorsport,s with Subaru entering the World Rally Championship (WRC) with the Legacy RS. While the marque had been partially present in the WRC since 1980s, success was scarce, but with the debut of the Legacy in the 1990 season, the tides began to turn. With an EJ20 under the hood, and with future legend Colin McCrae behind the wheel, the Legacy would earn Subaru its first WRC win in New Zealand in 1993.
That set the table for the age of the Impreza. Debuting in the 1993 Rally Finland, the Impreza would replace the larger Legacy, and turn Subaru into a rallying dynamo. WRC icons like McRae, Petter Solberg, and Richard Burns would drive the iconic blue and gold colors to 46 wins, earning a trio of drivers’ championships, as well as three consecutive constructors’ titles from 1995 to 1997. Subaru would stay in the game for years after, until the financial crisis of 2008 forced the program to close at season’s end.
Since then, Subaru continues to rally in the States, with a factory-funded team competing in the American Rally Association. Outside of racing’s top echelon, the EJ stays present in motorsport, powering Subies used by amateur rallyists worldwide.
World Rally eXperimental
Before it rallied, the Impreza was introduced in 1992. The small family car replaced the aging Leone, and came with the EJ20 equipped as standard. Subaru also produced a performance trim exclusive to the Japanese market, inspired by the Impreza competing in the WRC. Short for World Rally eXperimental, the first generation WRX was equipped with a turbocharged EJ20 sending 240 horsepower to all four wheels through a five-speed manual.
The impressive power, combined with Subaru’s symmetrical all-wheel-drive, gave everyday drivers a taste of what McRae and Solberg got to experience every weekend. Dressed up with massive fog lights and a hood scoop from the factory, the WRX had both the form and the function of a road-legal rally car.
It wasn’t until 2002 that the WRX was available to Americans, starting with the brand’s second-generation “Bugeye” Impreza. The first car to bring rally heritage and performance to North America, the WRX quickly found an American fanbase, turning into the perfect choice for year-round fun in the snowy states. The WRX became a staple of the enthusiast community, forming a cult following that would last far beyond the brand’s presence in the WRC.
And the EJ20 was a major key to that success. Powering the first car’s two generations, it established the WRX formula for generations, and would be the engine that showed Subaru’s rally-ready performance to the world.
The Achilles’ head-gasket
Although the EJ20’s layout is what makes the engine so iconic, it’s also the source of its biggest setbacks. Let’s get the two most infamous words out of the way: head gaskets. Those in the car community or around Subarus have likely heard war stories of blown gaskets, but in reality, most of these seal issues come from the EJ’s larger turbocharged flavor, the EJ25, often seen in the STI. The EJ20 has better cooling and thicker cylinder sleeves than its bigger brother, and as a result, tends to have far fewer problems.
That certainly doesn’t mean the EJ20 is bulletproof, however, as all turbocharged variants of the EJ family have issues to look out for. Poor cooling for cylinder four can lead to overheating, resulting in rod knock. This is typically most noticeable during cold starts before worsening over time. Turbocharged EJ20s also tend to go through oil quickly, and can leak from gaskets of cylinder head covers, as well as camshaft oil seals. For the more abused EJs, the damage could be as severe as cracked pistons.
Much of this would be less of a headache if it weren’t for how difficult maintenance is. The cylinders’ flat layout means that things can get tight in the engine bay, making wrenching on it both expensive and challenging.