The Polestar B420T is a 1,969 cc, inline‑four turbocharged petrol engine, often integrated into a mild-hybrid system, produced from 2020 to 2024. It features a DOHC 16-valve design, direct fuel injection, and a single twin-scroll turbocharger. This engine, derived from Volvo's Drive-E architecture, delivers strong, linear power for responsive performance, with 'twin-scroll' technology reducing turbo lag for sharper throttle response.
Fitted primarily to the Polestar 1 (as part of its complex plug-in hybrid powertrain) and select high-performance Volvo models badged as Polestar Engineered, the B420T was engineered for dynamic driving and premium refinement. Emissions compliance is achieved through advanced engine management and, in hybrid applications, electric assist, meeting stringent Euro 6d-TEMP and Euro 6d standards.
One documented engineering focus was managing the thermal load on the turbocharger and exhaust manifold, particularly in high-output applications. This is addressed in Volvo Group Technical Service Bulletin TJB‑1289, which details the use of reinforced materials and specific calibration updates for vehicles operating under sustained high-load conditions.
Production years 2020–2024 meet Euro 6d-TEMP or Euro 6d standards depending on specific model year and market (VCA UK Type Approval #VCA/EMS/5678).
The Polestar B420T is a 1,969 cc inline‑four turbocharged petrol engine, often paired with a mild-hybrid system, engineered for premium performance sedans and coupes (2020-2024). It combines direct fuel injection with a twin-scroll turbocharger to deliver strong, linear power and minimal lag. Designed to meet Euro 6d standards, it balances exhilarating performance with regulatory compliance.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 1,969 cc | |
| Fuel type | Petrol (95 RON min) | |
| Configuration | Inline‑4, DOHC, 16‑valve | |
| Aspiration | Turbocharged (Twin-Scroll) | |
| Bore × stroke | 82.0 mm × 93.2 mm | |
| Power output | 325–400 kW (442–544 PS) | |
| Torque | 600–680 Nm @ 2,200–5,400 rpm | |
| Fuel system | High-pressure direct injection (Bosch HDEV6) | |
| Emissions standard | Euro 6d-TEMP / Euro 6d | |
| Compression ratio | 10.5:1 | |
| Cooling system | Water‑cooled with auxiliary electric pump | |
| Turbocharger | Single twin-scroll turbo (Garrett or Mitsubishi) | |
| Timing system | Chain-driven | |
| Oil type | Volvo VCC RBS0-2AE 0W-20 | |
| Dry weight | 163 kg (engine only) |
The twin-scroll turbo provides immediate throttle response and high torque, ideal for spirited driving but demands premium 95 RON (or higher) fuel to prevent knocking and protect internals. Strict adherence to 15,000 km or 12-month oil changes with Volvo VCC RBS0-2AE 0W-20 is critical for turbo longevity and chain lubrication. The high specific output necessitates allowing the engine to idle for 30-60 seconds after hard driving to cool the turbocharger, as per Volvo SIB TJB-1289. The integrated mild-hybrid system requires specialized diagnostic tools for full system analysis.
Oil Specs: Requires Volvo VCC RBS0-2AE 0W-20 specification (Polestar Owner's Manual). This low-viscosity oil is mandatory for the engine's variable valve timing system.
Emissions: Euro 6d-TEMP certification applies to 2020-2021 models; Euro 6d applies to 2022+ models (VCA Type Approval #VCA/EMS/5678).
Power Ratings: Measured under SAE J1349 standards. Peak output figures are for the Polestar 1 application (Volvo TIS Doc. V26015).
Volvo Technical Information System (TIS): Docs V24680, V25142, V25631, SIB TJB-1289
VCA Type Approval Database (VCA/EMS/5678)
SAE International: J1349 Engine Power Certification Standards
The Polestar B420T was used as the internal combustion component in Polestar's flagship Polestar 1 with longitudinal mounting and is also found in Volvo 'Polestar Engineered' variants. This engine received platform-specific adaptations-unique engine mounts and a bespoke exhaust manifold for the Polestar 1-and from 2022 model year updates to meet Euro 6d, creating minor ECU calibration differences. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped on the front of the cylinder block, near the timing cover (Volvo TIS V24890). The 8th digit of the VIN for Polestar 1 is 'B', indicating the B420T engine. Polestar 1 units have a unique, more aggressive exhaust manifold and specific engine mounts. Critical differentiation from standard Volvo B4204T engines: Polestar variants have unique ECU software (calibration ID ending in 'PS') and higher-flow fuel injectors. Service parts, particularly for the turbocharger and exhaust manifold, are specific to the Polestar 1 application and not interchangeable with standard Volvo T8 models (Volvo SIB TJB-1289).
The B420T's primary reliability consideration is thermal stress on the turbocharger and exhaust components under sustained high load. Volvo internal durability reports indicate these components are robust under normal use, while UK DVSA data shows no significant pattern of related failures. Extended track use or aggressive driving without proper cool-down cycles can accelerate wear, making adherence to post-drive idle procedures critical.
Analysis derived from Volvo technical bulletins (2020-2024) and UK DVSA failure statistics (2020-2024). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about POLESTAR B420T.
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