Over the years Subaru have built excellent 6-cylinder engines that rival the power delivery and smoothness of even premium inline-6 engines from BMW.
In fact, the latest Subaru six-pot engine (EZ36D) may be one of the longest running engines still in production. With no, or very little changes since its introduction in 2007, the EZ36D, first found in the Tribeca is still in production in 2019 (12 years after). The fact that Subaru is still using this engine, with design dating over 12 years ago (and during a time where other car makers have made significant technological progress in their engine designs) shows that the engine was truly a masterpiece. It doesn’t include many new and advanced technologies, which you can find in Mazda’s recent SkyActive-X engines, for example, but still, for the power this engine is making, its fuel consumption, its smoothness, and its emission class is still top of the line.
The Subaru ER27
The Subaru EG33 H6 Engine
Before the current crop of six-cylinder Subaru Engines, Subaru had tried building six cylinder engines twice – the EG33 was basically an EJ motor with two cylinders added. For the differences between the EG33 and EZ30 I cannot recommend enough this video from Subi-Performance:
The Subaru EZ30 and EZ30R Engines
The EZ30 engine was a completely design. It wasn’t a retrofit, like EG33. The EZ30 was designed with power and smoothness as its main goal, as Subaru was trying to establish a name as a premium car manufacturer. One major goal with the design of this engine was to be able to fit it in the engine bay of the existing models, designed for 4-cylinder engines. For this reason, a completely redesigned engine block and timing chain systems had to be build. Read all about this engine at:
The Subaru EZ36D Engine
The next revision of the engine – EZ36D was launched in 2007 in the Subaru Tribeca and is still (2019) used in the latest generation Outback/Legacy models. During this period (over 12 years) the engine didn’t receive any significant updates.
The EZ36D is basically a big-block EZ30 mk II, which was introduced in 2003, with the then new “premium” Subaru Legacy and Outback.
The engine’s first update was made in 2003, with the launch of the new, Subaru Legacy/Outback, which was targeted at the premium segment and as such needed a powerful, 6 cylinder motor. The engine received new advanced variable valve timing and valve lift systems, electronic throttle body and gained over 20HP (raising the peak power output from 220HP to 245HP).
Header Image credits: By 160SX (talk) – 160SX (talk)’s file, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=7701348