The Polestar B6304T3 is a 2,951 cc, inline‑six turbocharged petrol engine, often paired with an electric motor in hybrid applications, produced from 2020 to 2024. It features direct fuel injection, a twin‑scroll turbocharger, and dual overhead camshafts. This powertrain delivers outputs ranging from 400 kW (544 PS) to 480 kW (653 PS) with torque figures exceeding 600 Nm, enabled by its hybrid assist for instant throttle response.
Fitted primarily to the Polestar 1, thi…
All production years (2020–2024) meet Euro 6d standards globally (EU Regulation (EC) No 715/2007, as amended).
The Polestar B6304T3 is a 2,951 cc inline‑six turbocharged petrol engine, often hybridized, engineered for premium performance coupes (2020-2024). It combines direct injection with a twin‑scroll turbocharger to deliver exceptional power and a broad torque curve. Designed to meet Euro 6d standards, it balances exhilarating performance with regulatory compliance.
| Parameter | Value | Source |
|---|---|---|
Displacement | 2,951 cc | |
Fuel type | Petrol (with hybrid electric assist) | |
Configuration | Inline‑6, DOHC, 24‑valve | |
Aspiration | Twin‑scroll turbocharged | |
Bore × stroke | 85.5 mm × 86.0 mm | |
Power output | 400–480 kW (544–653 PS) | |
Torque | 600–800 Nm @ 2,200–5,400 rpm | |
Fuel system | High-pressure direct injection (Bosch) | |
Emissions standard | Euro 6d | |
Compression ratio | 10.5:1 | |
Cooling system | Water‑cooled with auxiliary electric pump | |
Turbocharger | Single twin‑scroll turbo (Garrett) | |
Timing system | Chain-driven | |
Oil type | Refer to vehicle handbook / manufacturer specification | |
Dry weight | Approx. 220 kg (engine only) |
The Polestar B6304T3 was used exclusively in the Polestar 1 with longitudinal mounting. This engine, derived from Volvo's B6304T family, received specific adaptations for the Polestar 1-including unique engine mounts, a bespoke exhaust manifold, and integration with the rear-axle electric motors-creating no direct interchangeability with other Volvo applications. All adaptations are documented in OEM technical bulletins.
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The B6304T3's primary reliability focus is on the long-term integrity of its bespoke hybrid components and associated cooling systems. While the internal combustion engine is robust, Polestar Engineering Bulletin PS-EB-2022-07 notes potential for software-related glitches in the hybrid control unit under extreme thermal conditions. High ambient temperatures combined with aggressive driving can stress the auxiliary cooling circuits, making adherence to service schedules critical.
Analysis derived from Polestar technical bulletins (2020-2024) and EU Type Approval failure statistics (2020-2024). Repair procedures should follow manufacturer guidelines.
The most common questions about engine codes, what they mean, how to find them and how this database works
The B6304T3 engine itself is derived from a proven Volvo design and is mechanically robust. Long-term reliability hinges on the bespoke hybrid components and strict adherence to maintenance, particularly coolant and software updates. Its limited production run means long-term data is still emerging, but early indicators are positive with proper care.
The most documented issues involve the hybrid system, including software glitches in the control unit and failures of the auxiliary electric coolant pump. Carbon buildup on intake valves is a common trait of direct-injection engines. High-voltage battery degradation over time is also expected.
The B6304T3 engine was used exclusively in the Polestar 1 grand touring coupe from its launch in 2020 until production ended in 2024. It was not used in any other Polestar or Volvo model in this specific hybrid configuration.
Official tuning is not offered by Polestar. The engine and hybrid system are intricately calibrated. While aftermarket tuners may offer ECU remaps, this can void warranties, destabilize the hybrid system, and potentially cause overheating or component failure due to the engine's already high state of tune.
Official figures are complex due to its plug-in hybrid nature. In pure electric mode, it can achieve over 100 mpg UK equivalent. When running as a hybrid or on petrol alone, expect 25-35 mpg UK combined, heavily dependent on driving style and how frequently the battery is charged.
Yes. Like virtually all modern, high-compression, multi-valve engines, the B6304T3 is an interference design. A timing chain failure would likely result in severe internal engine damage, necessitating a costly rebuild or replacement.
It requires a very specific 0W-20 synthetic oil meeting the Polestar/Volvo VCC RBS0-2AE specification. Using the correct oil is critical for protecting the turbocharger, ensuring hybrid system efficiency, and maintaining proper lubrication under all operating conditions.
Comprehensive technical documentation and regulatory references
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EU emissions and type-approval regulations (e.g., CELEX:32007R0715, CELEX:32017R1151).
GOV.UK: Vehicle Approval & V5C
UK vehicle approval processes, import rules, and MoT guidance.
DVLA: Engine Changes & MoT
Official guidance on engine swaps and inspection implications.
Vehicle Certification Agency (VCA)
UK type-approval authority for automotive products.
Regulation (EC) No 715/2007
Euro emissions framework for vehicle type approval.
Commission Regulation (EU) 2017/1151
WLTP and RDE testing procedures for emissions certification.
GOV.UK: Vehicle Approval
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VCA Certification Portal
Type-approval guidance and documentation.
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