Next Subaru WRX STI could get 400-hp from a 2.4-liter boxer

Yet another report puts Subaru’s FA24 2.4-liter boxer four-cylinder in the next-generation WRX and WRX STI. Not only that, the story in Japan’s Car Sensor magazine (translated) seconds a Forbes report from February of this year that the hardest-core Scooby will make 400 horsepower and 361 pound-feet of torque from a high-output version of the 2.4-liter. As we said a few months ago, a 400-hp Subaru would become the most powerful factory official Subaru sold in the U.S., ever. Car Sensor explains that Subaru moved to the 2.4-liter because of the engine’s better emissions and drivability. What’s more, now that the WRX STI isn’t irrevocably tied to its rallying motorsports results, Subaru felt it doesn’t need to lean on the 2.0-liter displacement provided by the EJ20 still put to use in the Japanese WRX STI or the FA20F in our WRX. The rumored output would mark a substantial step up from the 310 hp and 290 lb-ft available from the current 2.5-liter in the WRX STI. It’s not clear yet where Subaru will rate 2.4 for use in the WRX.

The Car Sensor report placed the FA24 in the context of Subaru’s plan to have 80% of its lineup powered by three small-displacement turbocharged engines, the 2.4-liter at the top. The FA24 already motivates the Ascent, Legacy, and Outback, making 260 hp and 277 lb-ft in all three models. Getting to the 400 mark would be made possible by toughened internals and additional boost. A six-speed manual is a given. The CVT will need some help, however. Car Sensor suggests the current Lineartronic unit can handle no more than 295 lb-ft. It’s inevitable Subaru will work out some sort of self-shifting option, since its EyeSight driver assistance tech doesn’t work with a manual transmission, and we can’t imagine Subaru removing EyeSight when it’s found on the current WRX. It’s possible Toyota could step in with an assist, similar to how Toyota is apparently consulting on the all-wheel-drive system in the next-gen cars — perhaps with bits taken from the complex driveline in the Yaris WRC. The coming WRX should arrive in the first half of 2022. At the other end of the tuning scale, the BRZ and Toyota 86 have been rumored with the 2.4-liter, but making around 255 hp and 200 lb-ft.

Below the 2.4-liter, Subaru is said to be working on a 1.5-liter turbocharged mill to replace the 2.0-liter naturally aspirated engine that serves models like the Impreza and Crosstrek. Above that will be a 1.8-liter turbocharged engine slotting into the next Levorg, and perhaps a replacement for the naturally aspirated 2.5-liter four-cylinder in our Legacy and headed for upper trims of the Crosstrek.

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