What is the engine model of the Impreza STI?

[VonMakayla]

The engine model of the Impreza STI is EJ204, which is a 2.5L turbocharged gasoline engine with a maximum power of 221 kW and a maximum torque of 407 N·m. It is paired with a 6-speed manual transmission. The Impreza STI is a 4-door, 5-seater compact sedan under the Subaru brand. The Impreza STI features blackened headlights, and the grille section abandons the ordinary version's strip-style grille for a more sporty mesh design. A large air intake on the front hood highlights the engine's turbocharged characteristics. The lower air intake on the front bumper is larger in area, the fog lights are decorated with chrome rings, and the air ducts on both sides of the front bumper can also provide a large amount of cold air to the intercooler.

[MacCole]

The engine of the Impreza STi can be considered its soul, with the EJ207 and EJ257 being the most iconic models. As early as the 1990s, the first-generation STi adopted the EJ20 series, which later evolved into the EJ207 exclusive to the Japanese market. This 2.0-liter horizontally opposed turbocharged engine became a star in the tuning scene, with its 8,000 rpm redline and twin-scroll design delivering exhilarating high-revving power when tackling mountain roads and corners. For the U.S. market, Subaru switched to the EJ257, expanding the displacement to 2.5 liters, which unleashed stronger torque at lower revs, providing thrilling acceleration from a standstill. Both models retained Subaru's signature symmetrical all-wheel-drive layout, with the EJ207 featuring VF-series turbos and later versions incorporating AVCS variable valve timing. However, these engines were gradually phased out by 2019. Looking back, it's no surprise they became JDM classics, given their ability to easily reach 400 horsepower in stock form.

[LondynFitz]

No JDM performance car enthusiast would be unaware of the STi engine models. The Japanese domestic market primarily uses the EJ207, while the North American market gets the EJ257—both featuring a horizontally opposed turbocharged layout. The EJ207 is purebred rally heritage, with a more compact design, reinforced crankshaft and pistons, making it particularly suited for track tuning. In contrast, the EJ257's 2.5-liter displacement offers greater practicality for daily driving, delivering significantly quicker off-the-line acceleration, though its high-speed performance is slightly inferior. Subaru's insistence on air-to-air intercoolers over liquid-cooled systems proves adequate for aggressive driving. I've seen tuners bore the EJ207 out to 2.2 liters, achieving over 1,000 horsepower with forged internals, though stock configurations tend to be most durable when left unmodified. Both engines share a critical dependency on timing belt maintenance, requiring replacement every 100,000 km.

[DiKinsley]

The Subaru Impreza STi primarily features two classic engine variants: the Japanese EJ207 and the North American EJ257. The key difference lies in their displacement designs—the EJ207 is a 2.0-liter, while the EJ257 expands to 2.5 liters, both being horizontally opposed turbocharged engines. Personally, I prefer the tuning style of the EJ207. Its redline reaches a thrilling 8,000 RPM, paired with a twin-scroll turbo for razor-sharp throttle response. The relentless push of acceleration at high RPMs is utterly captivating. Though the EJ257 has a lower rev limit, it offers a more relaxed driving experience in urban settings. Both engines are mated to the DCCD all-wheel-drive system, with precisely matched gear ratios that clearly communicate engine traction shifts during aggressive downshifts. However, they share a common flaw: fragile piston rings, especially prone to oil consumption under prolonged high-load conditions. Subaru later addressed this in the FA series, but the EJ remains the true essence of STi.

[Diane]

When it comes to STi engines, the most famous are undoubtedly the EJ207 and EJ257. The EJ207 was primarily found in models for the Japanese market, with a 2.0-liter displacement, and its design was more focused on track performance, featuring reinforced connecting rods and a lightweight crankshaft, allowing for exceptionally rapid RPM climbs. On the other hand, the EJ257 was the mainstay for the U.S. market, with a 2.5-liter displacement that provided more abundant torque in the low RPM range, resulting in smoother gear shifts when paired with a six-speed manual transmission. In actual driving, the EJ207 truly comes alive when revved above 5,000 RPM, with a high-pitched and sharp engine roar, while the EJ257 is better suited for daily commuting, with less noticeable turbo lag. Both engines follow Subaru's tradition of using an open-deck cylinder block design, offering more room for aftermarket modifications than one might expect. However, their factory stability is indeed not as durable as contemporary engines like the RB26 or 4G63.

[VanDelaney]

The STi engines mainly follow two paths: the Japanese-spec EJ207 and the US-spec EJ257. The former has a 2.0L displacement and adheres to a semi-closed deck block design for enhanced structural strength, paired with a single turbo twin-scroll system. This setup is particularly noticeable during mountain runs, where the VTEC-like explosive power feels even more aggressive than Honda's, though it requires maintaining high RPMs to unleash its full potential. In contrast, the EJ257, with its increased 2.5L displacement, comes factory-equipped with a larger turbocharger, delivering noticeably crisper acceleration between 60-100km/h. Both models feature Subaru's Active Torque Vectoring system, ensuring precise throttle control when exiting corners. Interestingly, the EJ207's factory compression ratio is designed lower, allowing direct tuning to Stage 2 with 98-octane fuel, while the EJ257 is more fuel-sensitive with a higher risk of knocking. Driving these two engines reveals their distinct characters: the EJ207 feels like a purebred racehorse, whereas the EJ257 offers the versatility of an all-around hunting dog.