L15B7 · 1.5 turbo I4. What the stock hardware is estimated to support, where it breaks first, and the honest path to more.
The Honda Civic Si (10th gen, 1.5T) is rated 205 hp (SAE net (secondary listing) · US market) at 5,700 rpm and weighs 2,906 lb (US curb, sedan (secondary listing)), or 14.2 lb/hp. On enthusiast estimates its stock internals are taken to about ~350 hp, the fuel system to around ~280 hp, and the stock turbo(s) are taken to about ~260 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
EngineL15B7 · I4
Bore × strokenot sourced in this audit
Compressionnot sourced in this audit
Inductionsingle turbo
Fuel systemdirect
Rated power205 hp · SAE net (secondary listing) · US market @ 5,700 rpm
Torque192 lb-ft @ 2,100 rpm
Redlinenot sourced in this audit
Stock boostnot sourced in this audit
Transmission6MT
DrivetrainFWD
Curb weight2,906 lb · US curb, sedan (secondary listing) · 14.2 lb/hp
GenerationFC1/FC3 (2017–2020); the 11th-gen Si (2022+) is rated 200 hp at 6,000 rpm · 2017–2020
rotating assembly ceiling · fails first: head gasket margin near 300 hp, rods after · 93 AKI · no named source: site planning estimate · site planning figure ~350 hp; no named L15B7 tuner source was fetched
Induction ceiling~260 hp
stock turbo / supercharger ceiling · fails first: stock turbo out of efficiency · 93 AKI · no named source: site planning estimate · site planning figure ~260 hp
Fuel system~280 hp
stock fuel-system ceiling · fails first: HPFP · 93 AKI · no named source: site planning estimate · site planning figure; no named source in this audit
Clutch (manual)~250 hp
stock clutch torque capacity · fails first: stock clutch slip · no named source: site planning estimate · site planning figure; no named source in this audit
Cooling (sustained)~320 hp
thermal ceiling for sustained load · fails first: charge-air heat soak · 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: none named yet; method: the analyzer plans on the lower bound of each range
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