JAPAN AWD /// platform file
Subaru WRX STI (VA, 2015–2018) build guide
EJ257 · 2.5 turbo flat-4. What the stock hardware is estimated to support, where it breaks first, and the honest path to more.
Same family, other generations and variants: WRX STI (VA, 2019–2021)
The Subaru WRX STI (VA, 2015–2018) is rated 305 hp (SAE · US market) at 6,000 rpm and weighs 3,386 lb (US curb, base (Limited 3,444–3,448 lb)), or 11.1 lb/hp. On enthusiast estimates its stock internals are taken to about ~380–470 hp, the fuel system to around ~360 hp, and the stock turbo(s) are taken to about ~350–460 hp. Below: the sourced spec sheet, the limit sheet carbuildcheck analyzes against, and the platform's community-documented weak points.
Units
01 Spec sheet sourced
EngineEJ257 · 2,457 cc · flat-4
Bore × stroke99.5 × 79 mm
Compression8.2:1
Inductionsingle turbo, cross-flow intercooler, 14.7 psi max boost
Fuel systemport (sequential multi-port)
Rated power305 hp · SAE · US market @ 6,000 rpm
Torque290 lb-ft @ 4,000 rpm
Redlinenot sourced in this audit
Stock boost1.01 bar (14.7 psi), gauge
Transmission6MT only (DCCD)
DrivetrainAWD
Curb weight3,386 lb · US curb, base (Limited 3,444–3,448 lb) · 11.1 lb/hp
GenerationVA (2015–2021); GR/GV 2008–2014 rated 305 hp at 3,384 lb; GD 2004–2007 rated 300 hp · 2015–2018 (305 hp); 2019–2021 cars are rated 310 hp (own record) · pre-facelift (before the applied model (Subaru letters), Subaru’s term for the facelift)
Verified againstSubaru of America, 2015 WRX STI specifications (PDF) (primary, read 2026-09-06); Subaru of America, 2015 WRX STI press release (primary, read 2026-09-06); Subaru of America, Subaru marks STI 30th anniversary (primary, read 2026-09-06) · The mass rests on one document.
02 What stock parts support enthusiast estimates
Engine internals~380–470 hp
rotating assembly ceiling · fails first: ringlands on the hypereutectic pistons (t3), then liners past 500 whp · 93 AKI / E85 · source: 8020 Automotive, FA20DIT vs EJ257 · the block and pistons are put at 375–400 whp (t1), 400–450 whp on E85 (t2), roughly 470–560 crank at the 20 % AWD loss the site uses; the site plans on ~380 hp crank, well under the ringland band
Induction ceiling~350–460 hp
stock turbo / supercharger ceiling · fails first: stock VF48 out of efficiency (DSPORT stopped at the stock-turbo limit near 370 whp on E85) · 93 AKI for the planning figure; the upper bound is E85 (DSPORT ran 21 psi) · source: DSPORT, Test & Tune 2017 WRX STI part 3 · 370 whp on E85 (t2) is ~460 crank at 20 %; the site plans on ~350 hp on pump fuel
Fuel system~360 hp
stock fuel-system ceiling · fails first: stock injectors and pump on E85 · 93 AKI · no named source: site planning estimate · site planning figure; no named fuel-ceiling source in this audit
Clutch (manual)~330 hp
stock clutch torque capacity · fails first: stock clutch slip (DSPORT fitted a stage-2 clutch for its E85 build) · source: DSPORT, Test & Tune 2017 WRX STI part 3 · site plans on ~330 hp
Cooling (sustained)~380 hp
thermal ceiling for sustained load · fails first: oil temperature and starvation on track · no named source: site planning estimate · site planning figure; no named source in this audit
Tuning limitsenthusiast estimates, crank hp on the stated fuel; sources: 8020 Automotive, FA20DIT vs EJ257; DSPORT, Test & Tune 2017 WRX STI part 3; IAG Performance, IAG 550 vs STI Type RA short block; method: the analyzer plans on the lower bound of each range
Planning figures, conservative by design, never a manufacturer claim. How these are used in the score →
03 Where it breaks first community-documented
Ringland failure is the EJ257's signature move (IAG: failure-prone ringlands). A proven protuner and conservative timing matter more than any part on this list.
EJ oil starvation in long corners is community-documented; baffled pan or accusump before serious track use.
On an EJ, tune quality is the build. Cheap off-the-shelf maps kill more of these than any hardware choice (community consensus).
04 The typical path
Stage 1 tune → intake → downpipe → intercooler → Stage 2 tune. Fueling before E85; the clutch before sticky tires.
Analyze your WRX STI (VA, 2015–2018) build
Tap your mods, set a goal. Score, weak link, roadmap. Free, no login.
Check this build →
buying used? check the history first — the link gets you 20% off
↗Partner link
↗Partner linkPartner link: may earn carbuildcheck a commission at no extra cost to you. The stock limits, weak points and upgrade path on this page are documented independently and never influenced.
power outgrows the stock wheel and tire package firstWheelHero ↗Partner linkUS
Partner link: may earn carbuildcheck a commission at no extra cost to you. Fitment is per-platform, so check bolt pattern, center bore, offset and tire size against your own car before ordering anything, and note this retailer ships within the US. The stock limits, weak points and upgrade path on this page are documented independently.
05 Related platform files