Everything you need to know about the EJ20x and EJ20Y engine

Everything You Need to Know About the EJ20X EJ20Y Engine

The EJ20X and EJ20Y engine is a 2.0 liter turbocharged engine that is becoming fairly popular lately with people that are looking to swap a JDM engine into their USDM Subaru. It is fair to say that they are readily available, and they are typically priced just at, or slightly below $1,000. Those factors make this engine very tempting for a swap, but there are a lot of details about these engines that you want to have a clear understanding of before you purchase one for your project.

What is an EJ20X EJ20Y

First, this engine was found in the Liberty Turbo, and Legacy GT in other parts of the world. It a little difficult to pin down all of the exact years of cars that this engine was in, but roughly speaking they were as follows:

In Australia:

2003 - 2006 Liberty GT EJ20X – Automatic only

2004 – 2006 Liberty GT EJ20Y – Manual only

In Japan

2004 - 2009 Legacy GT EJ20Y - Possibly for both auto and manual?

2008 - 2014 WRX - EJ20X - Possibly for both auto and manual?

It appears that both engines were in the 2006 Liberty GT tuned by STI in Australia in 2006. It also appears that the EJ20Y engine was available after 2005 in some Legacy GT’s in Japan, and they may have made more power, similar to the STI Tuned Liberty GT from Australia.

2015+ STI - EJ20Y engine designation, but this is not the same as the earlier EJ20Y engines

What is confusing here is that it appears that the engine designation for the 2015+ STI is EJ20Y. But thanks to Dave at Rallispec and Mike from Roger Clark Motorsport who checked a number of part numbers, I can tell you that even though this newer STI engine is designated as a 20Y, it still has the same build as the previous STI EJ207 engines. The key features here are that the pistons are the same as the previous EJ207, as are the cylinder heads, and these newer STI's still have the metal red intake manifold, etc. What is important to know is that if the EJ20Y engine you are looking at is from an STI, it will have the red metal manifold, and it will still use the STI twin-scroll turbo where the older version that was not in the STI will not.

If you are looking at a newer-ish EJ20Y engine, that intake manifold is a key detail to pay attention to so that you know what you are getting. The turbo on the engine and the gasket set that would fit it as well are another key detail.

The EJ20X and EJ20Y (Non-STI) are 2.0 liter, Open Deck EJ series engines with a 92mm bore and 75mm stroke which fits with the majority of the other non-STI turbo EJ20 engines in this timeframe. The biggest difference is that this engine has a 9.5:1 compression ration which is much higher than other turbo engines of this time, and it was Subaru’s first engine that used AVCS on both the intake and exhaust valves (Dual-AVCS). This engine was also one of the first, if not the first Subaru turbo engine to use a twin-scroll turbo.

What do those differences mean?

In terms of putting this engine into a US spec car, the first main detail is that because it is different in so many ways, this will not be a simple or direct swap for any USDM car.

The largest potential issue is the high compression ratio that this engine has. The 9.5:1 compression will require a re-tune on the fuel that you are running here in the US to run safely. And because of that high compression ratio, your tuner will have to be fairly conservative with the timing to keep the engine running safe. That will most likely reduce the power and performance of this engine.

If you are going to run E85 in stead of pump gas, this high compression ratio will not be nearly as much of a hinderance, if any at all for this engine. It is definitely the ideal fuel to run in this engine here in the states, and if you do plan to run both E85 and pump gas, there will most likely be a large difference in performance depending on which fuel you are running.

The dual-AVCS also poses some challenges. If your car has intake AVCS, or intake and exhaust AVCS, it will be somewhat challenging to get that to work with this engine because the JDM engines use different pick-ups on the cams for the cam position sensors. At a minimum, you would need to install the USDM cams into he JDM heads to get the sensors to read correctly. If you do not have exhaust AVCS in your car, it will be fairly challenging to get that to work, and it would be simpler to plan on eliminating the exhaust AVCS.

Overall, because of the differences, it would be easiest to swap one of these engines into a USDM car where you could delete the AVCS all together.

Lastly the twin scroll turbo that comes on the EJ20X and EJ20Y (Non-STI) also pose a bit of a challenge because the up-pipe, turbo, and down-pipe all use flanges and gaskets that are unique to the EJ20X and Non-STI EJ20Y. This means that any of the twin-scroll STI turbos or exhausts will not work on the EJ20X/Y unless you swap all of the components out for the ones that did come on the STI. This has proven to be a critical detail to note if you are planning to use the turbo that comes on this engine.

The turbo that comes on the EJ20X is a VF38, and the EJ20Y came with a larger twin-scroll version of the TD04 turbo that came on the 2.0 liter WRX here in the US, the TD04-HLA-19T turbo. The later (or EU model?) Legacy GT with the EJ20X/Y (possibly 2007+) came with the VF45 turbo. Remember that these turbos use unique flanges and manifolds, so if you want to swap to an STI spec turbo, then entire exhaust from the header on must be swapped to get that turbo to fit.

The last detail worth noting is that because of all of the differences in the components used in these engines, there are not very many US parts that are compatible with these EJ20X/Y engines. The AVCS solenoids are unique to them, as are a number of gaskets, not the least of which are most any of the gaskets associated with the exhaust and turbo. Parts can be sourced, but because they have to come from overseas, you need to keep in mind that they will be more expensive and will typically come with much more lead time than a part for a US spec car.

Overall I would say that if you are looking for an inexpensive and simple engine to put into your USDM Subaru turbo, this engine is not an ideal candidate. If you have different goals, and plan on only using the longblock, and you are planning on running a higher octane fuel like E85, this engine would be a much more ideal option for you, but there may be other better choices out there still. More than anything, the purpose for putting this article together is to give you as many important details about the build and function of these engines so you can make the best decision for your project.

Hope that helps, and Stay Tuned!