Review the Subaru EJ20 Engine STI WRX Comparison

EJ20 Engine Spec Review

EJ20G is the first EJ20 engine with a turbocharger. The engine features DOHC cylinder heads and oil piston spray jets to cool the engine. It also has low compression ratio pistons (8:1) and fuel nozzles 380cc. Bucket-style HLA engines have lightweight valves and an air-cooled intercooler. They produce power of 220hp/6400 (Subaru WRX Wagon) or 275hp/6500 for Subaru WRX STI version II. Mitsubishi TD04 turbochargers were used to power engines for automatic transmission. For manual transmission, the engine was equipped with TD05. Source URL

The EJ20 engine has an aluminum cylinder block with dry cast iron sleeves/liners inside, just like its predecessor. The EEE, the most popular version of the naturally-aspirated engine, has aluminum alloy cylinder heads with SOHC design (single overhead camshaft). The EJ20 head has four valves per cylinder and central-located spark plugs. The intake valves have a diameter of 36 mm, while the exhaust valves are 32 mm. A timing belt drives the camsh shafts via the crankshaft. Every 60,000 miles, the timing belt must be changed. Source URL

Other EJ20 Series Engines

Other displacement versions of the EJ series include EJ15, EJ16 and EJ18. The Subaru FB engine family’s new naturally-aspirated version, the FB20 engine, replaced the 2.0L EJ20. Source URL

Subaru began production of SOHC engines with an open-deck block design. They also used EJ20N names (Ej201, Ej202, etc.). These engines featured new SOHA cylinder heads, lightweight pistons, and an intake manifold tuned to low RPMs. The power of the EJ201 engine is the same 125 horsepower at 5,600 rpm. The EJ202 engine is more powerful due to its light cylinder block, 4-2-1 exhaust headers, and another intake manifold. It produced 138 horsepower at 6,600rpm and 138 lbft (187 Nm) at 4, Source URL

Subaru claimed that they reduced friction losses by 28% by using lightweight pistons and connecting rods. The CO2 emissions were reduced by 4%. Fuel consumption was reduced by 10%. The engine is more environmentally-friendly because it produces the same power as the EJ20, but with a wider range of torque. Source URL

EJ20 vs FB25

This motor is a more powerful modification to FB20 and features many innovations and technologies. The motor has an aluminum cylinder block and identical stroke, but 94 bore cast iron sleeves add more displacement. The cylinder walls are 3.5mm thick. Subaru used restyled pistons to reduce friction in the block and reduce compression index to 10.0:1. Source URL

EJ20X and EJ20Y

The EJ20X (Non-STI) and EJ20Y (Non-STI) engines are 2.0 liter Open Deck EJ series engines that have a 92mm bore and 75mm stroke. They fit in with most of the non-STIs turbo EJ21 engines from this time. This engine has a 9.5:1 compression ratio, which is higher than any other turbo engine in this era. It was Subaru’s first engine that used AVCS on both intake and exhaust valves (Dual AVCS). This engine was also the first Subaru turbo engine to use a twin-scroll turbo. Source URL

EJ203 and EJ204

There are also EJ203 and EJ204 engines. The first engine has an electric throttle and a mass air flow sensor. EJ204 has double overhead camshaft cylinder heads and variable valve timing on intake camsh shafts, also known as AVCS. Its capacity is 155 HP. The later version has a capacity of 190 HP.

EJ20 Max Mileage and Life Expectancy

With proper maintenance, the life of naturally aspirated EJ21 engines is approximately 150,000 miles (250,000 km).

Common Problems with Subaru EJ20 

EJ20 Engine’s knocking noise. The engine has a problem with the 4th cylinder. The cylinder is hotter and the cooling is worse in this area. If the piston or rod starts knocking, the engine will be cold at first and then warm after a period. This requires an engine rebuild. Oil leaks. Oil leakage is a common problem with camshaft oil seals and gaskets on cylinder head covers. Source URL

When machining EJ20 heads for this swap, you should be aware that they are susceptible to cracking. Cracks can form on older EJ21 heads with higher mileage or higher mileage. This happens when cracks form at the spark plug hole and radiates to the valves. You should not machine a head casting if it cracks or is starting to crack. They should also not be re-used. Source URL

Can you buy an EJ20X and EJ20Y engine parts in the US?

It is important to note that there are not many US parts compatible with the EJ20X/Y engines. They are unique in that the AVCS solenoids and gaskets are unique. There are also a number gaskes that are unique to them, the most important of which are the gasket that is compatible with all components of the turbo and exhaust. Parts can be purchased, but they must be imported from overseas and will take longer to arrive. Source URL

What year did the Subaru Legacy have the EJ20Y engine?

Both engines were in the 2006 Liberty GT tuned by STI Australia in 2006. The EJ20Y engine was also available in Legacy GTs in Japan after 2005. They may have produced more power than the STI Tuned Liberty GT from Australia. Source URL

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