What Is The Most Reliable Subaru Engine?

What Is The Most Reliable Subaru Engine?

Subaru enjoys a worldwide reputation as a superior engine manufacturer. The best Subaru engines blend power, efficiency, performance, and dependability – and they often last well over 200,000 miles. But which is the most reliable Subaru engine of all time? Keep reading to discover our Top 4 picks for the best Subaru engine in history, considered from both OEM and aftermarket viewpoints.

Subaru EZ36D

The EZ36D engine is probably the most popular 6-cylinder from Subaru. It was based on the earlier EZ30 and featured thinner inner-cylinder sleeves and asymmetric con rods to accommodate a larger bore and stroke. Modifications to the drive cam led to an increased overall engine length for this powerplant that was used in 2010 – 2019 Outbacks.

The EZ36D delivered its maximum 256 hp at 6000 RPM and achieved an impressive 247 lb-ft of torque at 4400 RPM. This engine is well-suited for a supercharger kit installation and is broadly accepted as a superior version of its EZ30 predecessor. Like the EZ30, when mechanical problems do occur with the EZ36D, they are typically minor with quick and affordable fixes.

However, according to Wikimotors, “You shouldn’t waste time and try to increase power without the use of a turbocharger, it doesn’t make sense. If you choose the installation of a supercharger kit, then you can reach 400+ horsepower on stock internals. Both these options are expensive, therefore it might be cheaper to buy a faster car.”

Subaru EJ20T WRX STI

The EJ20T WRX STI engine from Subaru is a flat-four boxer, generally found in performance-focused WRX and STI Imprezas. Its wide availability and easy affordability make it a top aftermarket choice that delivers appreciable horsepower and torque. These engines typically produce about 197 hp at 6000 RPM, and roughly 217 ft-lb of torque at 6400 RPM.

All versions of EJ20T Subaru engines feature an air-to-water intercooler, as well as closed-deck engine blocks with built-in piston oil ejectors.

The 500-pound EJ20T features an aluminum head and block, 92-mm bore, and 75-mm stroke. You can easily identify an EJ20T by the plug coils, each having two M6 bolts. Some of the valve covers will also show labels that read 4CAM 16VALVE. Plus, you’ll see clearly visible horizontal lines below and above the spark plug holes.

Dust Runners asserts, “Ideal for low to mid RPM ranges and torque-dominated performance, this engine is deemed to be used in some applications in drifting, race tracks, and even drag racing. It is also a good engine swap for enthusiasts who want to taste the savory crisp of the EJ20 engine.”

Subaru FB20D

The FB series was originally offered as 2.5-liter and 2.0-liter naturally aspirated engines. First announced in 2010, FB was the first new generation of Subaru engines offered since the EJ series. It marked the beginning of the 3rd-generation of flat-4 powerplants from Subaru.

Notable FB20D features include:

  • 146 hp at 6000 RPM
  • 145 lb-ft of torque at 4200 RPM
  • Cast aluminum block and head material
  • Dual overhead cams with 4 valves per cylinder

FB20T’s feature a smaller bore (84-mm) with an increased piston stroke range (90 mm), meant to boost fuel economy and reduce emissions without sacrificing power. Asymmetrical connection rods and ultra-lightweight pistons keep the rotating assembly lightweight. The FB20D weighs in at just about 350 pounds.

Engines Work states, “The use of lightweight pistons and connecting rods helped the brand to reduce friction losses by 28%. CO2 emissions were decreased by 4% while the engine consumes 10% less fuel. Thus, in comparison with the EJ20, the FB20 is more eco-friendly while having the same output and a broader torque strip.”

Subaru EJ257

The EJ257 from Subaru is a 2.5L engine with rally racing roots. However, it has proven to be an excellent power plant for a variety of purposes. It was initially designed for use on the 2004 Impreza WRX STI.

This engine features a 4-cylinder horizontally-opposed configuration, which accommodates a lower gravity center. In stock form, its 3.92-inch bore and 3.11-inch stroke produce a peak power output of 300 hp at 6000 RPM and a maximum torque of 290 lb-ft at 4000 RPM.

Subaru’s Active Valve Control System (AVCS) enables variable valve timing, and the intake cam is monitored and controlled by the ECU. The camshaft is able to be adjusted as much as 35 degrees, which allows timing optimization throughout its entire RPM range.

If there’s a downside to this engine, it’s that it has been linked to some piston-related issues, and broken ring lands have caused the doom of more than a few EJ257s. Still, overall, it’s known worldwide as a terrific multi-purpose aftermarket engine. If you’re searching for a Subaru 2.5 engine for sale, consider this one.

Which Subaru Engine Is the Most Reliable?

There’s no doubt that Subaru has an iconic history of producing long-lasting, highly dependable engines. And while no engine is perfect, our choice for the best Subaru engine in history is the EZ36D.

What can we say? It has an excellent record for dependability, and when it needs work, the components are widely available and don’t break the bank. Plus, we love all that power!