The Upgrade Guide for the Subaru WRX (FA20DIT) Turbo

The Upgrade Guide for the Subaru WRX (FA20DIT) Turbo. The Subaru WRX (VA) from 2015 to 2021 is one of the best modern tuner vehicles on the market. It responds well to both bolt-on upgrades and E85 fueling, and it produces adequate power for the price. Much of this is attributed to the WRX’s powerful FA20DIT. The FA20 is powered by a turbocharged 2.0 liter direct injection flat-four engine that produces 268 horsepower and 258 lb-ft of torque out of the box. Many auto aficionados regard it as one of the few cars still available with a six-speed manual transmission.

We’ve recently looked at WRX intercooler upgrades as well as WRX downpipe/j-pipe upgrades, and now it’s time to talk turbos. A turbo boost for a WRX is ideal for people wishing to extend their power band and take their WRX to the next level. In this tutorial, we’ll go through everything turbo on your WRX, followed by a look at the best turbo kits on the market.

The Upgrade Guide for the Subaru WRX (FA20DIT) Turbo

FA20 Turbo Upgrade Fundamentals

The Garrett MGT2259 journal bearing, twin-scroll turbo is standard on the 2015-2021 Subaru WRX. It is internally wastegated and oil cooled with a 50.3 mm compressor wheel. The GT2259 can make roughly 375 horsepower with full bolt-on upgrades and E85 fueling before it starts to fall off and run out of steam. It runs out of gas after about 350 horsepower on pump gas.

Upgrading to a “big turbo” on the WRX is a fairly frequent option that has been standard since the WRX’s introduction in the 1990s. A larger turbo will not only offer you more peak power, but it will also increase the entire power range over stock. After 5,800 rpm, the stock turbo starts to lose power, and upgrading to a larger unit will allow you to maintain making power well past 6,000 rpm without requiring enormous amounts of advanced ignition timing.

However, the standard turbo normally has less lag than a larger turbo and is more responsive at lower loads. The turbo on the WRX runs at 16 PSI on the stock setup, however it does allow for brief bursts of overboost that can reach 22 PSI. On staged tunes, most tuners will run the factory turbo at around 19 PSI. Larger turbos often enhance that by at least 3-4 PSI.

What kind of power can the FA20 handle?

When upgrading the WRX’s turbo, it’s critical to understand how much power the FA20 can hold before the internals fail. It’s not an exact science, but most people agree that the connecting rods are the engine’s weak point. Tuners were destroying connecting rods on engines left and right in the early days of the FA20 due to applying too much torque too early in the power range. This has given them an unjustified image for being too weak, although they are the most common point of failure on the motor.

The factory FA20 connecting rods are generally thought to have a limit of 350 wheel torque. After that, most tuners would argue that you are using your engine on borrowed time. Typically, the pistons and block will be good long past 400 wheel horsepower, though if you are changing the connecting rods, it makes sense to install a set of forged pistons. When going with forged internals, ARP head studs are another popular modification.

It’s crucial to note that 350 horsepower is far from a definitive figure, and many WRXs have failed at that or lower power levels. A lot of it has to do with hiring recognized and respected Subaru tuners, such as Phat Botti and Bren Tuning.

The Fundamentals of Twin-Scroll Turbo

The stock WRX MGT2259 turbo, as well as any enhanced turbo packages for the WRX (VA), is a twin-scroll turbocharger. A twin-scroll turbo is comparable to a regular turbo, although it improves on some of its shortcomings. Twin-scroll turbos, often known as “divided” turbos, are relatively new to the OEM turbo sector. The WRX’s twin-scroll turbo differs from a standard single-scroll turbo in how the exhaust pulses are directed.

Turbochargers operate by utilizing exhaust gas pulses to power a turbine, which in turn powers a compressor. The compressor pulls in and compresses outside air before delivering it to the engine, allowing it to produce more power. Turbochargers are placed directly onto exhaust manifolds to capture these exhaust gases. The turbine inlet housing is the area where the turbocharger and the manifold connect. This is where the distinction between single and twin-scrolls becomes apparent.

A single volute (channel) runs from the turbine inlet to the turbine housing in a single-scroll turbo. The turbine inlet of a twin-scroll is separated into two volutes that run to the compressor. Because engines release exhaust fumes in pulses due to not all cylinders firing at the same time, the twin-scroll design is more efficient. These distinct pulses can interfere with each other in a single-scroll, resulting in reversion (when exhaust gases become caught in the combustion chamber) and poor scavenging.

The exhaust gas pulses on a twin-scroll, on the other hand, do not interfere with each other as much because of the divided inlet. Because no kinetic energy is lost, the turbo can function more efficiently and create higher and more constant amounts of boost.

How much power can I get out of my WRX with a turbo upgrade?

Users can see anywhere from mild to enormous benefits with a WRX turbo upgrade due to increased boost and cfm from a larger turbo. The base turbo produces around 350 wheel horsepower, and most turbo modifications begin in that range. The FA20 can produce approximately 450-500 wheel-horsepower while remaining in its basic configuration.

The issue with using a large turbo on the FA20 is both the OEM placement and the lack of fuelling. Because of the WRX’s low-mount turbo, it’s difficult to maintain fitting larger turbos, and ultimately you’ll need to relocate – which isn’t feasible owing to the design. Furthermore, the FA20’s stock fuelling is unable to keep up with builds above 500 wheel-horsepower.

The FA20 employs only direct injection and has no port fuel injectors. The factory injectors can produce around 500 wheel-horsepower, but they lose power quickly – especially on ethanol. To consistently exceed 500 wheel-horsepower, you’ll need to upgrade to auxiliary port fuel injection. There are a few kits available for the WRX, but they are pricey and require new engine management to operate.

Supporting Mods for the FA20 Turbo Upgrade

Before considering a WRX turbo upgrade, make certain that you will be safe and dependable. When upgrading, the major items to consider are the intake/exhaust, cooling, feeding, boost control, and tune. Turbos are not the first improvement you should consider for your WRX. We’ll look at the supporting mods you’ll want and require before going full turbo on the Rex.

Improving the Intake/Exhaust System

If you want to put a bigger turbo on your WRX, you must have an improved exhaust and intake. In terms of exhaust, you’ll need a full turbo-back exhaust with 3″ diameter piping. Take a look at our WRX downpipes/j-pipes guide to see what works best for your setup. The factory exhaust is only 2.5″ long, which is insufficient for a larger turbo and will quickly choke out any gains.

You will also require an improved intake system. The basic intake will produce roughly 350 horsepower, and any turbo increase will require something more free-flowing. Not all intakes will fit all turbo kits, so double-check fitment before ordering. In any case, most units do not fit the stock unit, necessitating an update.

Enhancing Cooling

Before installing a larger turbo, you need also upgrade your WRX’s intercooler. The stock intercooler can only handle stock power levels; anything above requires aftermarket assistance. Check out our guide to WRX intercooler upgrades to find which one is best for your project. Upgrade your charge pipe, which connects the intercooler to the turbo, as well. After 350 horsepower, the stock charge pipe becomes quite restricted, so make sure you purchase one that fits your intercooler.

You should also think about replacing your radiator, especially if you live in a hotter climate like Arizona or Texas. The higher the power levels you push, the more heat the engine will eventually produce, therefore coolant temps can be a concern after long runs on larger builds.

Enhancing the Fueling

The FA20DIT, as previously stated, uses direct injection fueling. There are no proven and dependable injector improvements on the market right now, but as previously noted, the true upgrade would be to add supplemental port fuelling. A larger in-tank fuel pump is also recommended, and the common possibilities are Deatschwerks 65c and 300c.

Users should really consider pursuing the E85 and flex-fuel path on their WRX to get the most bang for their buck out of their turbo installation. With the addition of ethanol, tuners will be able to run lower air-to-fuel ratios with more ignition and camshaft timing without experiencing detonation issues. This means significant increases in horsepower and torque.

With no further changes, the stock turbo can produce 300 wheel-horsepower on an ethanol blend, making the potential with an aftermarket turbo very astounding. The WRX can run ethanol without any changes, but most users choose for a flex-fuel system to check ethanol levels.

Boost Control FA20

Another critical part of any turbo upgrade is boost control. Almost every tuner will demand that customers switch from the basic 2-port system to an electronic 3-port system. The Electronic Boost manage System with three ports will manage boost considerably more precisely and accurately than the factory system. Most tuners even advocate it when utilizing the factory turbo, let alone with any turbo enhancements.

Turbo Tuning for Subaru WRX

The most significant component of any WRX turbo upgrade build is probably tuning. Before putting a turbo kit on your FA20, you must first install a tuning solution. A transaction with a tuner should ideally be settled before your new turbo is fitted, not later. Some tuners demand certain mods when updating to a specific turbo, so plan ahead.

Tuning Subarus is possible both online through E-tuning and in-person on the dyno. The Cobb Accessport is a common device for tuners and one of the most well-known and trusted on the market. Make certain that you work with a renowned and high-quality tuner who is prepared to collaborate and answer your inquiries. Two of the most common options are Phat Botti tuning and Bren tuning.

Data logging is also a crucial aspect of keeping your automobile safe, so keep logging even after your tune is complete to ensure everything is still in working order. Monitoring your air-to-fuel ratio, knock sensors, and boost is critical to keeping your automobile healthy. Inquire with your tuner about what you should be looking for.

Best Turbo Kits for Subaru WRX

Now that we’ve covered everything it takes for a safe and dependable WRX turbo upgrade, let’s have a look at the best turbo kits for the FA20 WRX on the market. There are numerous turbo kits available, and these are our top four suggestions from among the many. These provide an excellent balance of performance, precision, quality, and cost.

  • Excessive Turbo Systems
  • Forced Efficiency
  • SteamSpeed
  • Upgraded SoCal Performance compressor

1) Extreme Turbo Systems WRX Turbo Kits 2015+

Price: $6,545.00+

350-1,2000 wheel-horsepower is expected.

The Upgrade Guide for the Subaru WRX (FA20DIT) Turbo

The Extreme Turbo Systems (ETS) 2015-2021 Subaru WRX Turbo Kit is the first item on our list. The ETS Kit was one of the earliest products on the market and has withstood the test of time. ETS offers six distinct turbo kit sizing options. Precision Turbos manufactures all of them. They provide turbo choices for the 5858, 5558 Gen 2, 5862 Gen 2, 6062 Gen 2, 6266 Gen 2, and 6466 Gen 2.

two dump tubes, two wastegates, headers, and a downpipe are standard features on all ETS kits. The ETS kit has been used in some of the most memorable FA20 builds, and with the larger PT turbos and correct supporting upgrades and ethanol feeding, this kit is capable producing as much as 1200 wheel-horsepower.

This is by far the most expensive kit, but it includes everything needed for a complete turbo construction, including the downpipe and headers. However, it is the most tested and can produce by far the highest power – depending on the turbo selected.

2) FA20DIT Forced Performance Turbo Kits

Price: $3,099.00+

Power to be expected: 440-475 wheel horsepower

The Upgrade Guide for the Subaru WRX (FA20DIT) Turbo

The Forced Performance FA20 Blue Turbo Kits are next on our list. FP has built a reputation as a reliable turbo maker for both WRXs and Evos, and their FA20 range does not disappoint. They have two versions, both of which are FP Blues with internal or external wastegates and optional coated turbine housings.

The center housing rotating assembly (CHRA) is what distinguishes the two. The first has a journal bearing, whereas the second has a Xona Rotor Ball Bearing. The Xona Rotor costs an additional $1,100 on top of the journal ball bearing, but it reduces spool time and improves longevity. On E85, both turbos flow 57 lbs/min and can produce up to 475 wheel horsepower. This turbo was specifically designed for the FA20 and has a very favorable power curve.

3) Turbo Kits SteamSpeed FA20

Price: $1,799.00+

Power should be expected: 350-500 wheel horsepower

For the WRX, SteamSpeed provides two alternative turbo kits. The first has a GEN2 67R+ Ball Bearing Turbo, while the second has a GEN2 71R Ball Bearing Turbo. Both are direct replacements for the OEM turbo and work flawlessly with regular “Stage 2” kits.

The 67R+ is the smaller of the two turbos. It can produce 350-400 horsepower on regular petrol and up to 425 horsepower on E85. It combines their existing 67R turbo with the 71R’s ball bearing. With E85 gasoline, the 71R can produce up to 500 wheel horsepower and flow an amazing 59 lbs/min. It is also a direct OEM replacement that will fit in the stock spot as well as most “Stage 2” kits.

The SteamSpeeds are not as reliable as the FP or ETS kits, but they are an excellent budget choice with decent power. They are unlikely to be as consistent as the FP or ETS kits, but they are also less expensive and have been shown to produce respectable power.

4) Upgrade SoCal Performance V4 GT2259

Price: $1,005.00+

500-560 wheel-horsepower is expected.

Our final entry is not a turbo kit, but rather an enhancement for the stock GT2259 turbo. SoCal porting is a newcomer to the WRX industry, but they already have a solid reputation. Instead of a new turbo, SoCal offers to enhance the OEM turbo’s compressor wheel and turbine shaft. Their whole package also includes the OEM turbo’s machining, re-contouring, clipping, rebuilding, and full porting and polishing.

You send them your FA20DIT stock turbo, and they update it in-house before returning it to you. This is their fourth-generation compressor wheel design, and it provides the best flow ever. It also keeps all of the stock housings for true OEM fitment. Power improvements are significant on the stock turbo, and users may achieve up to 560 wheel-horsepower with full bolt-ons and E85 fueling.

However, keep in mind that the factory turbo will most likely not dissipate heat as well as a larger aftermarket turbo. This means that not only will longevity suffer, but EGTs will climb as well. However, it is the cheapest choice and will provide the best fitment.

Related : The Downpipe Upgrade for the Evo X

Summary of FA20 WRX Turbo Upgrades

Upgrading the turbo on your WRX is an excellent way to achieve a wider powerband with higher peak performance. When it comes to putting a new turbo to your WRX (VA), the sky is literally the limit with the right mods. There are possibilities for different degrees of build, ranging from moderate (350-400 wheel-horsepower) to some of the world’s fastest automobiles (1,200+ wheel-horsepower).

To upgrade the turbo on your FA20DIT, you’ll need some help. The higher the power level, the greater the strain on the engine. Anyone who wants to create considerable power should consider improving the connecting rods and purchasing a constructed block.

All of our suggested turbo kits focus dependability, performance, and price. The ETS system is by far the most expensive, but it is also the most tested and contains other exhaust modifications. For years, the FP Blue turbos have been a staple in the WRX and Evo communities, and their FA20 line is superb. The SteamSpeed kit is a good low-cost solution that can deliver high numbers but has questionable durability. Finally, the SoCal porting V4 upgrade for the OEM turbo is a nice alternative for individuals who want to keep their stock hardware but get some power.

All kits are intended to fit the 2015-2021 WRX; the real question is what size turbo you require. The larger the turbo, the more power, but going too big can eventually reduce mid-range power at the expense of peak top-end power. It all relies on your construction priorities.