A Closer Look At The EJ and FA Engines

Aside from Subaru’s famous rally history, what really makes models such as the WRX and the STI so appealing?  One of the key elements that resonates with new and seasoned enthusiasts is that flagship Subaru rumble. The Subaru rumble is the unique engine noise derived from Subaru’s flat-four engine design, particularly found in the EJ205.

The EJ has been in production since 1989, however, in 1999 as Japan developed the EJ205 for Impreza models. The sport of Rally Racing was quickly gaining popularity on a worldwide scale as the internet was becoming more of a household appliance across America especially. Additionally, popular tuner magazines often wrote articles about rallying and did photo shoots of Japanese WRX models that piqued the interest of the sport compact community stateside. When news hit that the WRX would land in US markets in 2002, the EJ205 would be launched into the stratosphere with an abundance of aftermarket companies eager to get their hands on this new turbocharged AWD platform.

For the US markets, the EJ205 made around 227 HP at 6000 PRM with 217 LB-FT of torque that peaked at 4K RPM. Learning from earlier turbocharged sport compacts such as the Eagle Talon, Mitsubishi Eclipse, and the heavy hitters such as the Supra and RX-7, the aftermarket immediately started developing front mount intercooler kits, cold air intakes, and downpipes which would otherwise generate substantial results in other models. At the time, 227 HP in 2002 was not bad at all, but everyone wants more power, and more boost. The EJ205 was about to meet its threshold. When it comes to modifying Subarus with the EJ205, you must choose between fast, or reliable.

And throughout the 2000’s enthusiasts and tuner shops all tested the limits of the EJ205. And truth be told, the EJ205 was not meant to hold a substantial amount of horsepower. As the 2JZ’s of the world were making 1000+ HP and Mitsubishi’s 4G63 was getting tuned to the moon, the EJ205 couldn’t keep up. But this was never Subaru’s intentions. The bugeye WRX is a rally-inspired sedan designed to be enjoyed sensibly within it’s limits.

Yet Subaru always had a wildcard in their sleeve and had an answer to Mitsubishi’s Evolution in 2003.

When the Mitsubishi Lancer Evolution landed on showroom floors in 2003, it developed 271 HP through a 5-speed transmission. And truth be told during the time, it completely wiped the floor with the WRX. The Evo was faster, stronger, and was more appealing than the WRX. When Subaru was battling the perils of Rally, Mitsubishi also displayed their dominance in the WRC, and had drivers such as Rhys Millen piloting and campaigning Mitsubishi’s rally cars in famous hill climbs such as pikes peak. However, Subaru remained confident with a straight poker face as they released the STI for the US markets in 2004.

The STI debuted with Subaru’s new blob eye headlight design, a larger hood scoop, a bigger rear wing, the cherry red STI Subaru Tecnica International logo, and those blue suede seats. Everyone had to have one. More importantly, the STI came with the legendary EJ25 which developed 300 HP and was mated to a strong 6-speed manual transmission.

Like a gang initiation, enthusiasts and tuning shops jumped off the WRX, and went straight into the STI. One of the biggest hurdles for the EJ205 was trying to smooth out the powerband after performing modifications such as an intake and downpipe. What happens, is that both the intake and downpipe increase the boost and airflow enough to where the factory ECU cannot process these increases outside of its own parameters. This would cause the EJ205 to boost cut, fuel cut, and ultimately fail. During the early 2000s tuners tries to rely on fuel controllers that would hard wire into the ECUs wiring harness, and these fuel controllers would try to manipulate the ECU into thinking that it made more boost and made more fuel volume.

However, one of the most integral companies for the Subaru performance industry, COBB Tuning, worked relentlessly to develop a solution for the EJ’s quirky tunability issues. It was then in 2004 the COBB Accessport was developed.

COBB Tuning V3 Accessport 2002-2005 WRX

 

COBB Tuning designed their highly coveted Accessport to be able to tune key areas of the EJ205 and EJ25 so that mods such as an intake, downpipe, and fuel upgrades could be sustainable for performance, and everyday drivability. And as the Accessport advanced with their V2 models, and now V3 models, there are tunes that you can download onto your Accessport that will work with current and future modifications.

 

THE EJ HAS LIMITS, AND THE HEARSAY IS TRUE

As legendary as the EJ still is whether it be the 205, od the 25, it has its limits. Subarus are known not to handle a substantial amount of horsepower, and the EJ has inherent failure points.

The biggest reputation of failure for the EJ are the ring lands, head gaskets, and rod knock. Because the EJ is a flat-four engine design, the pistons are designed with larger bores. The purpose of the larger piston bore is to make up for the shorter engine stroke. The problem is that on the first compression ring on the piston, there is hardly a distance or gap between the first piston ring, and the top surface of the piston. What happens is that carbon can fill the area between the piston top and the first compression ring making that first compression ring stick. Additionally, because of the lack of space between the first compression ring and the top of the piston, detonation will break the edges of the piston due to too much boost, or a lean running condition due to a poor tune, causing that cylinder to completely lose compression.

 

HEADGASKETS

The reason why EJ motors are synonymous with losing head gaskets, is that the cylinder heads were designed as open-deck heads. Open deck heads for the EJ engines lack clamping force due to the large open casting pockets in the heads with lack of buttresses or cylinder liners in the short block which allows the cylinders to flex during movement. Now if you are making 400+ horsepower, then a closed-deck conversion should be performed, and it’s highly labor-intensive. The open-deck pockets in the short block would get machined out and inserts would be installed to not only strengthen the engine, but it provides more surface area for the head gasket seal.

Now companies like IAG Performance does make closed-deck short blocks that take care of all the machine work, and to allow the EJ to handle substantial amounts of horsepower.

IAG Performance 750 Closed Deck w/Case Halves 2002-2021 WRX / 2004-2021 STI

ROD KNOCK

Why are EJ’s known for rod knock? There are a few heavy variables. One is the design of the flat-four engine. The EJ engine has many oiling flaws. One of them is the lack of crankcase volume. Meaning that there is little space between the main crankshaft journals in the short block. This naturally causes high oil pressure. Because of the high oil pressure, oil gets slung everywhere, and gets forced through Subaru’s poor OEM crankcase ventilation system design. The oil will go into the intake system where it causes excessive carbon buildup on the intake valves, and the tops of the pistons where it effects the octane rating of the gasoline by contaminating the air/fuel ratio into a lower octane level, which will cause detonation. This is why it is absolutely crucial that you get an upgraded your air/oil separator:

GrimmSpeed Air/Oil Separator Black 2008-2014 WRX 

Continuing with some of the EJ’s oiling challenges, the other major factor is the design of the oil pan, and the OEM pickup tube. There have been some documented cases of broken oil pickup tubes. What happens is that the oil pickup tube will develop a crack, which would make the pickup tube suck in air rather than oil. And air cannot lubricate rotating internal metal components which leads to engine failure.  

Regarding the oil pan, the internal design lacks baffling. And this issue is more prevalent for those who regularly track their Subarus. Because of the horizontally opposed cylinder design,  and entering high-speed corners, the oil will slosh to the other bank of the engine, leaving the other side with a lack of lubrication for the rod bearings, then things break. The main fix is an upgraded oil pan and pickup tube from the likes of Killer B Motorsport for example, to greatly improve the overall oiling system in your EJ.

 

Killer B Motorsport Aluminum Oil Pan Package 2002-2014 WRX / 2004-2021 STI

 

WHAT IS THE DIFFERENCE BETWEEN THE SHORT BLOCK AND LONG BLOCK?

For those of you who are new to engines in general, and read about them on the worldwide internets, you often read or hear about long blocks and short blocks. The engine as a whole, is made up of two major components. You have the short block which is the bottom block of the engine. This holds the crankshaft, connecting rods, and the pistons. The other main component is the head (or heads). So, in an inline-6 such as a 2JZ, the pistons are in a row, therefore, it only has one head. The head is the entire valvetrain of the engine. The head will contain the valves and camshafts. When you hear about a V6 or a V8, you will have (2) heads. And the engine will be shaped in a V-formation. In Subaru’s case, it is a boxer design much like the Porsche 911 where the heads attach on the side of the engine, and this is called a flat design due to the horizontally-opposed piston layout.

Regarding a long block, a long block is when the short block and heads are completely assembled together. If you need a new long block, this means that you need a new bottom end which is the short block, and the heads as well. The majority of the time if you experience engine failure, most will have their heads re-machined by a proper machine shop, while either rebuilding, or getting a new short block assembly.

 

HOW TO MAKE AN EJ LAST?

Despite its failure points which can be addressed, the EJ is actually a very reliable engine. With any turbocharged engine and especially modified engine comes a great responsibility in terms of maintenance. Simply put, you need to stay on top of the oil changes, timing belt services, spark plugs, and other general maintenance items. The problem is that the Subaru WRX and STI attract many young and new enthusiasts that treat the car as if it were indestructible. Driving it hard, launch after launch, and getting some local tuner hack to perform popping noises.

But on the other hand, there are others who like to test the limits of the EJ by adding too much turbo in hopes of hitting a large HP number. It’s just not sustainable for longevity.

Upgrade your oil pain and pickup tube, get an air/oil separator if your Subaru doesn’t have one already, get an Accessport, and keep your power levels at a sensible 300-350 AWHP. It may not be the fastest car on the road, but there is no argument between a rewarding driving experience, vs a blown motor and costly repair bills.

The Subaru EJ has a rich history and racing heritage for rally racing, grassroots motorsports, and time attack racing. Subaru continued the production of the EJ25 in the VA Subaru STI that ended in production in 2021. Pending the new design, it is rumored that the new STI will come as an all-electric model. However, that remains to be seen.

 

THE FA20F AND FA24F

IAG Performance 800 HP FA20 DIT Subaru Closed Deck Short Block 2015-2021 Subaru WRX

The WRX needed a revision after the highly desired GV chassis that had a very successful run mainly because of the aggressive body design of the sedan. Therefore, Subaru released the VA version of the WRX in 2015 that had a new engine design – to a degree. Although Subaru’s FA engine was used in naturally aspirated form in the BRZ and it’s co- Toyota partners the FR-S and 86, the turbocharged version would be released for the VA WRX.

One of the inherent flaws of the EJ engine design was the turbocharger placement that sat near the passenger-side firewall. The problem was that the exhaust housing of the turbocharger was inches away from the top mount intercooler which would cause heat-soaking issues. This time Subaru placed the turbocharger on the bottom-side of the engine, near the front of the car.

Regarding the fuel system, the FA engine was direct-injected meaning that instead of the fuel injectors spraying fuel through ports on the intake manifold, the injectors are installed right into the heads. Now direct injection helps with fuel economy and a smoother powerband. The FA20DIT makes 268 HP while the FA24 in the 2022 WRX makes 271 HP. However, the fuel system is much more complicated when compared to the EJ engine. You don’t have many injector options, installation and removal is far more complicated because you have to remove the plastic intake manifold, and the injectors can become stuck due to the continuous heat cycles, and the fuel rails have electrical sensors with a high-pressure fuel pump design in the engine. Bery susceptible for carbon buildup, make sure you get an air oil separator for this engine as well.

Compared to the EJ? The FA20 and the FA24 make a more efficient powerband when compared to the EJ205. To be fair, they must in order to keep up with modern and more powerful vehicles. More importantly, Subaru needs to adhere to all the guidelines of the EPA, local as well as local and abroad carbon emission laws on a worldwide production scale.

But in all reality, the FA and EJ share many Subaru parallels with the flat-four engine design. Whether it be more complicated or more advanced, sacrifices had to be made in order to produce an engine that was power efficient while being emissions compliant. The FA still accepts all the fun upgrades we love such as cat-back exhaust systems, they use a ‘J-pipe’ as opposed to a downpipe just because of the shape, and they love tunes, intakes, intercoolers, and such.

 

BUILT SHORT BLOCKS

Built short blocks mainly feature forged pistons and forged connecting rods. The purpose of forged pistons is to endure more heat. OEM pistons whether in Subarus or in other platforms, feature cast aluminum construction, and when exposed to more power, they cannot endure the heat which makes them more vulnerable to damage and/or melting.

Stronger connecting rods can handle more boost, and the failure point for connecting rods is being stretched to the point to where they separate from the rod caps. In built engines, they will also have better hardware such as ARP main studs,  and rod cap studs. All built engines are blueprinted, balanced, and have specific engine bearing clearances that are typically a little looser on the piston rings to endure more boost. When compared to an OEM EJ or FA motor, built engines can make more power from 500 HP all the way to 1000+ HP with supporting modifications. Will they last forever? Absolutely not which can be said for any engine. It depends on the tune, the maintenance, and howe much abuse you put that motor through.

IAG 700 Closed Deck Long Block Engine w/Stage 3 W25 Heads 2008-2021 STI

 

 

THE VERDICT:

The truth is, and this is aimed to those who are trying to make big horsepower numbers, is that there is no OEM Subaru production motor that can sustain over 400 horsepower. We all know that there is a tuner out there who has made over 400 WHP and he has put 20k miles on the motor so this must apply to all engines. Obviously, that is not the case. It depends on driving style, do you track the Subaru, or do you take it easy on daily commutes, how well is the motor maintained, etc. And yes, there are world-record setting WRX and STI models that make 7-second drag passes with well over 1000+ HP, and there are also 1000+ HP Subarus that contend in the unlimited class for World Time Attack.

But again, sensible is the key. Keep your mods at 350 HP and below, and just enjoy your Subaru. An intake, cat-back, catted downpipe, Accessport, and fuel upgrades that include a pump and injectors makes for a very fun car at pump gas. If you have the thirst for more power, make sure you have plenty of time, money, and patience to spare.