The EJ257 against FA20DIT. Subaru’s FA20DIT and EJ257 engines are two of its most popular performance engines. The EJ257 is regarded as one of the most recognizable and legendary tuner engines of all time. It powered every STi iteration in North America since 2004, and was consistently one of the best performance alternatives on the market. The FA20 debuted in 2012 and made its way into the Subaru WRX in 2015, where it quickly established a reputation for producing remarkable performance with excellent tunability.
Both boxer engines will be phased out of production in 2021, according to Subaru. The FA20 is still alive and well in the bigger displacement FA24, however the EJ series is no longer available in North America. It’s a shame, because both of these engines are incredible. They were both quite powerful out of the box, and they both had massive aftermarket support. Both engines have some unfortunate flaws, but they are relatively reliable.
Over the last few years, many enthusiasts have been debating whether the FA20 or the EJ257 is superior. This guide will teach you everything you need to know about both engines, including design, dependability, and, most significantly, performance and improvements. Let’s get this party started!
*There is also a naturally aspirated version of the FA20, the FA20D, but this article only covers the turbocharged FA20F (FA20DIT).
**Previously, we compared the WRX and STi, the two most prominent cars powered by the EJ257 and FA20 engines. When you get an opportunity, make sure to read that guide.
History of the Subaru 2.5 L EJ
Subaru first debuted the EJ series of engines as the successor to the departing EA series in the late 1980s. They originally unveiled the EJ25 in 1996, and the STi tuned variant, the EJ257, in 2004. In 2004, the EJ257 produced 300 horsepower and 300 torque, which were amazingly high figures for an engine powering an economy sedan at the time. It produced more power than its competition, the 4G63 in the Mitsubishi Evo, and received good marks from both enthusiasts and professional drivers.
Drivers quickly discovered ways to modify the EJ257, and within a few years, completely built versions with fully closed deck designs and forged internals began to appear on the market for truly high horsepower builds. The EJ257 has remained one of the most sought-after tuner engines of all time, and it has been used in a plethora of intriguing and one-of-a-kind projects. Even in 2022, many competition race teams swear by the EJ257 and all of its fabled splendor.
History of the Subaru 2.0 L DIT
Subaru first introduced the FA20DIT in the Japanese market in 2012. However, it made its way to the United States in the Forester XT in 2014, and the WRX in 2015. The FA20DIT produced 268 horsepower and 258 torque in the WRX, but for the Japanese market, Subaru increased the output to 296 horsepower and 295 torque. Although many critics were concerned about the FA20’s lower displacement than the outgoing WRX engine, the EJ255, the FA20 quickly turned its reputation around.
Within a few years, the aftermarket community had gotten their hands on the FA20, and mods and upgrades were plentiful. Though the internals were not as powerful as its competitor, the EJ257, making moderate power was much easier. The car is also E85 compliant out of the box, thanks to the newly built direct injection system, however it requires calibration for safe use.
Both engines were phased out after 2021. The FA20 because its successor, the WRX, joined the market, and the EJ257 because its outmoded design caused Subaru too many pollution worries. Still, FA20DIT and EJ257-powered vehicles are common on the road, and the engines will be supported by aftermarket vendors for a long time. Or at least until the electric vehicle revolution catches up with them.
FA20DIT and EJ257 Specifications
The following are the specifications for the Subaru FA20 vs EJ257 engines:
EJ257 and FA20DIT: Applications
Applications for FA20DIT
- Subaru Legacy 2.0GT DIT (JDM only) 2012-2014
- Subaru Levorg 2014+ (JDM & ADM only)
- Subaru Forester XT 2014-2018
- 2015-2021 Subaru WRX
- Subaru WRX S4 2015+ (JDM only)
Applications for EJ257
- Subaru Impreza WRX STi 2004-2014
- Subaru WRX STi 2015-2021
- Subaru Forester XT 2004-2005
- Subaru Legacy 2.5 GT 2005-2006
- Subaru Outback 2.5XT 2005-2006
Engine Design Differences Between Subaru FA and EJ
The EJ257 and FA20DIT engines are both flat-four, horizontally opposed boxer engines. This means the pistons are oriented sideways rather than vertically or at an angle, and they move side to side rather than up and down. Boxer engines have a lower center of gravity than inline or V type engines due to their unique structure. This enhances straight-line stability while reducing body roll in and out of corners. We previously did a thorough dive into the EJ257 with our engine guide, so be sure to check that out as well.
Engine Design and Modifications for the EJ257
Subaru designed the EJ257 engine in the early 2000s and has only made minor changes since then. The EJ257 engine has a 2.5L strengthened aluminum block, a semi-closed deck, and an 8.2:1 compression ratio. With a bore of 99.5mm and a stroke of 79mm, it boasts forged rods and hypereutectic cast pistons. For charge air cooling, the first model additionally incorporated sodium-filled exhaust valves and an integrated intercooler sprayer.
Subaru added a supplementary air pump for emissions in 2007, which required changes to the cylinder heads, resulting in new V25 heads to replace the existing B25 heads. The OEM turbo was also upgraded from an IHI VF39 to an IHI VF43 to address wastegate cracking issues by strengthening it to prevent boost creep.
Subaru updated the EJ257 with a new turbo (IHI VF48) and new W25 heads in 2008. They also improved their Advanced Valve Control System (AVCS), which previously just used intake cam timing. They also added a nitride-treated crankshaft and slightly strengthened connecting rods in 2009.
Subaru ultimately made some significant upgrades to the EJ257 when it was used in the limited edition WRX STi Type RA in 2018. They strengthened the pistons, installed new N25 heads, and raised boost from 14.5 PSI to 16.2 PSI for the first time on the STi. Subaru introduced the new EJ257 in the STi in 2019, and it stayed unchanged until 2021.
So, basically, Subaru’s only substantial changes over an 18-year span were to modify the heads, add exhaust cam timing, and increase boost by 1.2 PSI. As a result, power on the STi rose just marginally, from 300 horsepower in 2004 to 310 horsepower in 2021.
Design of the FA20DIT Engine
The FA20DIT is a 2.0L aluminum block engine with direct injection and 10.6:1 compression. It has hypereutectic cast pistons and rods, a forged crankshaft, and an open deck design. Furthermore, the FA20DIT longblock is a perfectly square engine with the same bore and stroke lengths.
Subaru’s FA20 engine debuted direct injection as the most significant change in 2012. Gasoline direct injection, also known as GDI or DI, is a novel fueling method in which atomized fuel is injected directly into the combustion chamber. This leads in more precise fuel injection timing, which decreases emissions while increasing torque. It does, however, have some drawbacks, notably carbon accumulation, which we will discuss further below.
Instead of the single-scroll turbos featured in the EJ25 family of engines, the FA20 employs a Garret GT2259 twin-scroll turbo. The twin-scroll design separates the exhaust gas pulses coming out of the exhaust manifold into two ports, or scrolls, that feed into the compressor wheel separately. This results in a smoother flow of exhaust into the turbo, allowing for improved cam timing and more pulse energy. When combined with GDI, it results in peak torque at relatively low RPMs, resulting in a significantly wider powerband.
EJ257 vs. Subaru FA20: Performance
The EJ257-powered STi can travel from zero to 60 mph in 4.8 seconds and the 14 mile in 13.3 seconds at 105 mph in factory configuration. It has a top speed of 159 mph, which is electrically and drag-limited. In 2004, the EJ257 produced 300 horsepower and 300 torque, and by 2021, horsepower had hardly increased to 310. Due to increased emissions regulations, the EJ257 actually lost 10 lb-ft of torque beginning in 2008, and only made 290-tq after that.
The EJ257 is also available in a slightly modified form in the STI S209, which is limited to 209 units. Because of greater boost pressure and a larger turbo compressor wheel and turbine, as well as larger injectors and a higher flowing fuel pump and intake design, this version of the EJ257 produces 341 horsepower and 330 tq.
Subaru’s FA20DIT engine had a shorter production cycle, from 2012 to 2021, yet it had a significant impact in the Subaru community. The FA20 produced 268 horsepower and 258 torque for its whole run in the USDM WRX.
Subaru upped power outputs for JDM models to 296 hp and 295 tq. The USDM FA20 can accelerate from 0 to 60 mph in 5.1 seconds and complete the 14 mile in 13.6 seconds at 102 mph. The FA20’s twin-scroll turbo and GDI technology allow it to compete with the bigger displacement STi.
Upgrades and modifications for the Subaru FA and EJ
With most of the background information out of the way, it’s time to get to the fun stuff. With a few easy bolt-on tweaks, the turbo architecture of both the FA20DIT and EJ257 has enormous potential. The engines’ upgrades are comparable, however there are some slight changes. Notably, the FA20 is more E85 friendly and comes standard with a more capable fueling system. Anyway, let’s get started and compare EJ257 vs FA20 upgrades.
EJ257 Upgrades and Modifications
Mods for the EJ257 that are the best:
- ECU Programming
- Injectors (Stage 2 and above)
- Fuel Pump (Stages 2 and up)
- (Stages 2 and up) Fuel Pressure Regulator
While the stock EJ257 is a perfectly enjoyable car, the real fun begins when you begin to modify it. The normal intake, downpipe, and ECU tuning are the most basic alterations for the EJ257. Intakes will produce 5-15whp/wtq, however the OEM intake is rather good and can tolerate power levels of up to 350-400whp without needing to be changed. Downpipes are by far the most prevalent EJ257 modification. They contribute 10-25whp/wtq by reducing exhaust flow restriction, depending on whether they are catted or catless.
ECU tuning is the most bang for your buck on the EJ257, yielding 25whq/wtq on its own. Subaru engines are notoriously temperamental and sensitive to changes in air-fuel and flow, thus any intake or exhaust modifications must be tuned.
Furthermore, the EJ257’s fuel system is nearly maxed out at “stage 2” and above, which means anything with a downpipe and tuning. Larger fuel injectors, a larger fuel pump, and a fuel pressure regulator are highly recommended (particularly for 2008 vehicles).
The EJ257 actually has no limits, and there are numerous 1000+hp builds out there. The STI aftermarket community is quite active, and new components are continuously being created and produced today.
FA20DIT Upgrades and Modifications
FA20DIT Mods That Work:
- ECU Programming
- Downpipe (J-Pipe)
- Fueling using E85
We’ve already looked at a number of FA20 enhancements, so we’ll simply go over them briefly again and link back to our other articles for you to read. Our guide to the best FA20 mods is an excellent resource that includes suggestions for mods as well as specific manufacturers. There are other articles on turbo improvements, exhaust upgrades, intake upgrades, and intercooler upgrades.
ECU tuning will undoubtedly be the most popular mod for the FA20 WRX. Simply tuning can result in 25-35whp/wtq and completely transform the powerband. Downpipes, often known as J-Pipes on the FA20 due to their design, are another popular modification. They add 10 to 25 whp/wtq by lowering constraints and enhancing cat placement by moving it downstream. Intakes can also boost power, 5-15whp/wtq, however the OEM intake on the EJ257 is quite capable below 350whp.
Intercoolers are also excellent improvements for folks who live in hotter regions or enjoy doing several pulls. The stock cooler is grossly small and quickly becomes ineffective after only a few runs. Because the fuel lines, fuel pump, and fuel injectors are already ethanol compatible, E85 fueling is fantastic for the FA20. Proper tuning is required to safely run more than a few gallons of ethanol at a time, but the benefits are enormous.
FA vs EJ: Reliability, Common Issues, and Power Limitations
We have already gone through the EJ257 in depth, so we will simply recap our guide here. With our guide, we also looked at the top four most common FA20 issues. Check out both for the complete rundowns.
EJ257 Common Issues
Cracked turbos, spun bearings, rod knock, and ringland failure are the most typical EJ257 issues. The fractured turbos were largely caused by the early VF39 wastegates and are no longer an issue on EJ25s manufactured after 2008. The following years have some concerns with overall turbo dependability, although they are generally fine.
The most serious and well-known problems with the EJ257 are rod knock, spun bearings, and ringland failure. These problems are frequently caused by repeated pre-ignition and detonation events in poorly tuned engines. Detonation, often known as engine knock, is commonly caused by lean air-fuel ratios, excessive timing advance, and high cylinder temperatures in Subarus. Repetitive knock events will eventually ruin connecting rods and pistons, as well as cause ringland failure.
One of the most common problems with the EJ257 is ringland failure, which occurs when the ringlands get shattered as a result of extreme heat and explosion. The ringlands keep combustion gases, heat, and oil out of the crankcase. When the ringlands fail, there is significant oil blow-by into the PCV system and crankcase, resulting in oil in the intercooler. Oil hunger difficulties can occur if enough oil leaks out, which frequently results to spinning bearings on the EJ257.
EJ257 Power Restrictions and Reliability
The EJ257 block can withstand a lot of power, but its internals aren’t nearly as tough. The block is considered to be good up to 400whp before needing to be updated. To withstand additional power, several aftermarket companies produce fully closed deck EJ257 blocks. The pistons are the next weak point, as the OEM hypereutectic cast pistons do not perform well above 375-400whp.
Anyone looking to push the EJ257 past 400whp should seriously consider a built block, forged pistons, reinforced rods (OEM are forged but not as strong as you might think), and head studs. Additionally, cylinder liner sleeves are a popular choice.
Proper maintenance is essential for the EJ257, which has been reported to easily exceed 200,000 miles in stock form. Modifications definitely reduce the EJ257’s lifespan, but even minor builds can reach 150,000 miles with appropriate maintenance and driving. The most serious dangers to EJ25 lifetime are improper tuning and untuned alterations.
FA20DIT Common Issues
The weak connecting rods and excessive carbon buildup are the main faults of the FA20. Many early WRXs had connecting rods snap the moment they were tuned on the dyno. While there is no definitive reason for this, most tuners agree the problem was pushing too much torque too early in the powerband. The twin-scroll turbo and GDI fueling produce exceptionally quick peak torque, but on the FA20s, this proved a death knell for engines generating more power than standard.
However, tuners discovered that massaging out the torque hit by 300-600 RPMs, so that peak torque did not reach until past 3,300 RPMs, was the most effective way to prevent premature rod failures. Because tuning has improved, most 2016+ WRXs do not have rod failures.
The other major concern with the GDI-powered FA20DIT is carbon accumulation. Because GDI sprays the fuel mixture directly into the combustion chamber, no fuel is washed over the intake valves during each combustion cycle. This makes them susceptible to carbon and soot buildup, which can lead to major problems with misfires, fuel efficiency, and performance over time. However, the vast majority of FA20 owners, more than 95%, will almost certainly never experience carbon buildup problems. The valves can be walnut blasted to remove carbon buildup, but without extra fueling, the problem will persist.
Unless you are currently suffering misfires and spark issues, cleaning your intake valves is probably unnecessary, however it never hurts. The usual preventative maintenance interval is 40-60,000 miles, depending on power levels and driving. Excessive idling and repeated short excursions where the engine is unable to warm up are the leading causes of carbon buildup in GDI engines.
Related : The FAQs about the Subaru WRX
FA20DIT Power Capacity and Reliability
The FA20DIT is a powerful engine. The block can handle more than 400whp without trouble. Companies, like the EJ257, provide closed deck versions of the FA20 for serious power builds. The internals of the FA20 are not quite as sturdy as those of the EJ257. The general belief is that rods and pistons are fine until around 350-375whp/wtq, at which point they will most certainly fail and need to be replaced. Anyone looking to push their horsepower past 400whp should seriously consider a built block, forged pistons and rods, and head studs.
Because the FA20 hasn’t been around as long as the EJ25 series of engines, there’s a lot less data on its dependability. However, preliminary results indicate that the FA20 is quite reliable. There are currently dozens of 150,000+ mile instances of stock motors with no difficulties due to appropriate maintenance and safe driving. Even moderately adjusted FAs have demonstrated the ability to travel far over 50-75,000 miles without trouble.
There haven’t been as many high horsepower FA20 builds as there have been on the EJ series of engines, but there are a few notable instances. Some builds have exceeded 800whp, and there are numerous 500whp+ 2015-2021 WRXs on the road today. For ultra high horsepower builds, GDI fueling usually needs to be supplemented, however there are some aftermarket alternatives available.
FA20DIT versus EJ257: A Comparison
Overall, the FA20DIT and EJ257 are both solid flat-four boxer engines with plenty of power and fun. The EJ257 is one of the most recognizable tuner engines of all time, and the FA20 is gradually establishing itself in the tuning community.
The EJ257 will offer the most power with the most aftermarket support, but the FA20 is no slouch either. Despite having a half-liter less displacement, its GDI and twin-scroll turbo help make up for it. Furthermore, the FA20’s larger torque curve allows it to scream off the line from a dig.
Which is superior? There is no definitive answer. The FA20DIT is the way to go for individuals searching for moderate power boosts while still getting good fuel economy and cutting-edge technology. However, for enthusiasts interested in extracting the most power and building a true racecar, the EJ257 is the clear winner.