Subaru FA20DIT: Everything You Need To Know

The FA20 engine is the new engine produced by the collaboration of two automakers – Subaru and Toyota. It powered Subaru’s BRZ and Toyota’s 86 in the form of a 4U-GSE machine. These guys are known for their outstanding balance of torque and aggressive power.

Subaru released a turbocharged version which we will discuss today, the FA20DIT.

Join me as we briefly discuss the engine’s design, potential, reliability, capabilities, and many more.

Let’s get right to it!

What are Subaru FA20DIT Engines?

Before we talk about the turbocharged version, let’s briefly recall its basic framework engine, the latest FA20, which was made by the then-Fuji Heavy Industries, now Subaru. The FA engines are alternates of the FB engines, but this FA20 engine focuses more on weight reduction and engine durability.

The whole FA series was developed for the Subaru BRZ and its first engine to be produced is the FA20D. It is designed to be mounted as low as possible for greater dynamic response and handling. It minimizes the polar moment of the chassis, or we can say, a lower center of gravity which applies to most performance-bred cars.

The FA engines feature a shorter intake manifold and a shallower oil pan to allow a shorter engine height as compared to the Subaru FB engines, but some engine parts are shared between the two.

Commonly known as the FA20DIT engine or the FA20F/FA20E engine, it is the turbocharged version of the FA20D, which was introduced in late 2012 for the 2012 Legacy GT (JDM), and then for the 2014 model year Subaru Forester in the United States market. This FA20 version came in a pressing way to replace the old EJ205 and EJ207 engines. FA20DIT engines were named by Wards’ Auto as one of their ‘Ten Best Engines’ list in 2015 and 2016.

This engine has a compression rating of 10.6, lower than the FA20D. A revamped variant of the FA20F was launched for the 2015 model year Subaru WRX that has revised camshafts, boost pressure, rocker arms, intercooler, and exhaust system.

Engine Specifications and Design:

  • Production Run: 2012 – Present
  • Cylinder Head Material: Aluminum
  • Cylinder Block Material: Aluminum
  • Configuration: Flat-4 (Boxer type)
  • Bore: 86 mm
  • Stroke: 86 mm
  • Valvetrain: DOHC four valves per cylinder
  • Displacement: 2.0 L (1998 cc)
  • Compression Ratio: 10.6
  • Weight: 377 lbs.
  • Maximum HP: 272 HP at 5,600 RPM
  • Maximum Torque: 258 lb-ft at 2,000 – 5,200 RPM

The engine block of the FA20DIT engines paid respects to the venerated FA20 block, which was made from aluminum. It has the same cylinder bore, and piston stroke dimensions squared at 86 mm for a fair balance of torque-y and a powerful output of such an engine.

Being a flat-four also comes with advantages, as we mentioned above, that they are a cut above their competition in terms of deck height and maximizing the space it occupies. It is smaller, much compact, and rally-bred; really cool engine to deal with, especially if you are planning to build one.

The sporty model FA20 got its own bag of twin-scroll turbocharged engines that badged as the FA20DIT or FA20F. It is equipped with Subaru’s own direct fuel injection system as well as two Garrett MGT2259S turbos that are capable of producing 16 psi (22 psi in the over-boost mode for several seconds) and can make 272 HP at 5,600 RPM and 258 lb-ft of torque available at 2,000 to 5,200 RPM.

The FA20DIT uses non-forged pistons, redeveloped heads that provide better airflow, and much-improved combustion chambers; new camshaft specifications, a plastic intake manifold with TGV (Tumble Generator Valve) inside, and added a new turbo manifold to use.

The cylinder heads are equipped with a variable valve timing system dual AVCS (Active Valve Control System), by Subaru, on both intake and exhaust camshafts. Apart from being a more balanced engine than the FB20, FA20 features a better and restyled bottom, new crankshafts, connecting rods, and pistons. The exhaust system includes a steel 4-2-1 exhaust manifold and is available on the naturally aspirated FA20D version.

Applications of the FA20DIT engine and their power ratings:

  • 2012 – Present JD Subaru Legacy 2.0 GT DIT
  • 2014 – Present Subaru Levorg
  • 2015 – Present JDM Subaru WRX S4
  • 296 HP at 5,600 RPM and 295 lb-ft of torque at 2,000 – 4,800 RPM
  • 2014 – 2018 USDM Subaru Forester (Forester XT)
  • 250 HP at 5,600 RPM and 258 lb-ft of torque at 2,000 – 4,800 RPM
  • 2014 – 2018 JDM Subaru Forester (Forester XT)
  • 276 HP at 5,600 RPM and 258 lb-ft of torque at 2,000 – 5,200 RPM
  • 2015 – Present USDM Subaru WRX
  • 268 HP at 5,600 RPM and 258 lb-ft of torque at 2,000 – 5,200 RPM
  • Rev Limit at 6,700 RPM

Engine Tuning, Upgrades, and Modifications

Subaru FA20DIT has already been equipped with a twin-scroll turbocharger and produces pretty decent power output numbers with its stock internals. It is really nice that the FA20DIT engine is a lot easier to increase the power compared to the naturally aspirated one; since the N/As need to install or make a turbocharger that can fit on that machine.

Since the FA20DIT has a turbo, you will just need a 3-inch aftermarket cat-back exhaust system, boost controller, cold air intake, and adjust the ECU. For vehicles with automatic transmission, it is ideal to have a transmission cooler. With these upgrades, it can give you at least 350 HP. Adding an aftermarket radiator is also fine, as well as a frontal intercooler; that would be enough for active driving.

If you want to further up your horsepower gains, you will need a new fuel pump, pulley, fuel injectors, and water/methanol injection. Also, include a transmission cooler and an aftermarket radiator. You can also opt to change your turbo if you are not satisfied with the current ones based on the GTX3076R. This kit is feasible to install on stock internals and can receive at least 400 HP and even 500 HP with the correct fuel RON.

Problems Surrounding FA20DIT Engine:

Even with the most well-designed and well-rounded engines, we have today, we cannot evade the natural tendencies of the materials or moving parts to be as good as they were new, which is not surprising. From the standard maintenance items up to the least affected by external factors such as age and usage, the engine will somehow deteriorate and need servicing. Here are some troubles that you might encounter with the FA20DIT engines.

The first problem is the carbon build-up. The ‘DI’ in the DIT stands for Direct Injection, and this technology helps improve the performance and efficiency of the engine. However, as marvelous as it is, there are flaws associated with this one; and the primary concern regarding this system is the carbon build-up.

So how does that happen?

Indirect injection, the fuel is directly sprayed in the cylinders. And also, engines produce oil blow-by that moves within the intake tract causing it to penetrate deep into the intake ports and valves, where it begins to form carbon deposits.

Once this carbon build-up goes out of control, the cylinders no longer have access to an optimal airflow because the deposits clog the intake ports, making them smaller over time, leading to drivability issues. You can expect the build-up to appear every 60,000 to 100,000 miles and does not need to address immediately.

The next issue we have here is the connecting rod. This is not a problem for the naturally aspirated but primarily concerns the turbo engine. Around the 325 to 250 torque range, connecting rods start to weaken. Since FA20DIT are beyond stock power levels, this is a significant concern.

Connecting rods issue needs serious attention, though, as it can lead to more devastating results such as engine knocking that needs a rebuild if it happens.

Also, what comes with the engine themselves are factory engine software or tune. There are reports that some owners are a little bit unhappy about what Subaru provided. Some say it’s pretty aggressive when boosting, runs too lean, and sometimes idles roughly.

To add, FA20DIT is a direct engine, I reiterate, and runs a bit leaner than the traditional port injection engines, which is the nature of DI.

Lastly, FA20DIT has issues with stalling. The problem might root from the cam gear, which leads to loss of pressure of engine oil. And when that happens, the engine might have difficulty cornering, lubrication, and even efficiency since engine oil provides all of that services.

It is crucial to provide your engine with high-quality oil and prioritize the overall running condition of the machine to be top-notch. Always use high-quality fuel since FA engines are meant to run on high octane fuel to have the best performance. Try changing the oil as much as two times than what is recommended as it allows more reliability and increases engine resources.

Summary

FA20DIT engine is a unique combination of efficiency, torquey feels, and performance. It produces decent power enough to be taken on a track session – if you feel like it and is also great for city driving with its fuel economy at 7.8 Liters per 62 miles. This engine is easy to mod and tune regardless of where you are and how do you want it; it doesn’t matter.

Though it has more common issues than the naturally aspirated but it really does make sense knowing the complex nature of turbo engines, and they have more parts that are likely to fail due to higher work effort. Always take note that pushing the connecting rods beyond their safe upper limits calls for caution because bent rods are detrimental to the engine.

Overall this engine is above average in its reliability; it needs some improvement on the lower speed range torque, but it is an excellent engine to experience high-performance in a compact form.

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