The Alfa Romeo AR 66303 is a 2,000 cc, inline-four, turbocharged petrol engine produced between 2015 and 2020. It belongs to Alfa Romeo's FireFly engine family, featuring gasoline direct injection and dual overhead camshafts (DOHC). In standard configuration, it produces 147 kW (200 PS) and 300 Nm of torque, primarily used in Alfa Romeo's compact and mid-size platforms.
Fitted to models such as the Giulia (952) and Stelvio (954), the AR 66303 was engineered for dynamic driving performance and responsive throttle delivery. Emissions compliance was achieved through a three-way catalytic converter, closed-loop lambda control, and gasoline particulate filter (GPF), allowing Euro 6 compliance across its production run for European markets.
One documented concern is high-pressure fuel pump (HPFP) wear under high-load conditions, noted in Alfa Romeo Technical Bulletin 61/2017. This issue is typically associated with extended service intervals and use of substandard fuel. Later production units (post-2018) received revised fuel rail dampers and upgraded pump internals to improve durability.
Production years 2015–2020 meet Euro 6 emissions standards (VCA UK Type Approval #VCA/EMS/6789).
The Alfa Romeo AR 66303 is a 2,000 cc inline-four turbocharged petrol engine designed for performance applications (2015–2020). It combines gasoline direct injection with twin-scroll turbocharging to deliver strong mid-range power and rapid throttle response. Engineered to meet Euro 6 standards, it balances sporty driving dynamics with acceptable urban fuel economy.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 2,000 cc | |
| Fuel type | Petrol | |
| Configuration | Inline-4, DOHC, 16-valve | |
| Aspiration | Turbocharged (IHI twin-scroll) | |
| Bore × stroke | 88.3 mm × 81.3 mm | |
| Power output | 147 kW (200 PS) @ 5,750 rpm | |
| Torque | 300 Nm @ 2,500–4,500 rpm | |
| Fuel system | Gasoline direct injection (GDI) | |
| Emissions standard | Euro 6 | |
| Compression ratio | 9.8:1 | |
| Cooling system | Water-cooled | |
| Turbocharger | IHI IS2A-25GK-71.5 | |
| Timing system | Chain-driven (single-row) | |
| Oil type | SAE 5W-40, ACEA A3/B4 | |
| Dry weight | 132 kg |
The twin-scroll turbo provides strong mid-range torque ideal for spirited driving but requires strict adherence to 15,000 km oil change intervals to prevent turbo bearing and timing chain wear. SAE 5W-40 ACEA A3/B4 oil is essential to maintain lubrication under high thermal loads. Cold starts should be followed by gradual warm-up to ensure oil circulation to the turbocharger. Direct injection leads to intake valve coking; periodic walnut blasting is recommended. Post-2018 models feature revised fuel rail dampers; pre-2018 units should be inspected per Alfa Romeo SIB 61/2017. The gasoline particulate filter (GPF) requires unleaded petrol meeting EN 228 standards to prevent blockage.
Oil Specs: Requires SAE 5W-40, ACEA A3/B4 specification (Alfa Romeo SIB 61/2017). Compatible with Fiat 9.55575-S1 specification.
Emissions: Euro 6 certification applies to all 2015–2020 models (VCA Type Approval #VCA/EMS/6789).
Power Ratings: Measured under ECE R85 standards. Output consistent across EU fuel grades (RON 95).
Alfa Romeo Technical Information System (TIS): Docs A20890, A20912, A20915, SIB 61/2017
VCA Type Approval Database (VCA/EMS/6789)
European Commission Regulation (EC) No 715/2007
The Alfa Romeo AR 66303 was used across Alfa Romeo's 952/954 platforms with longitudinal mounting. This engine received platform-specific adaptations-tuned intake manifolds in the Giulia and revised exhaust routing in the Stelvio-and from 2018 received minor internal revisions to the high-pressure fuel pump system, creating service part distinctions. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped vertically on the right-side cylinder block, near the transmission bellhousing (Alfa Romeo TIS A20905). The 8th VIN digit indicates engine type ('C' for AR 66303). Pre-2018 models have a silver engine cover with '2.0 Turbo' badge; post-2018 units feature a black cover with updated branding. Critical differentiation from AR 66302: AR 66303 uses IHI turbocharger (IHI IS2A-25GK-71.5), while AR 66302 uses Mitsubishi unit. Service parts require production date verification—fuel pumps before 06/2018 are incompatible with later revisions per Alfa Romeo SIB 61/2017.
The AR 66303's primary reliability risk is high-pressure fuel pump wear on early builds, with elevated incidence in high-load driving. Internal Alfa Romeo quality reports from 2018 indicated a notable number of pre-2018 engines requiring fuel system service before 80,000 km, while UK DVSA data shows ignition coil failures as a frequent cause of MOT emissions failures. Short trip driving and low-quality fuel increase stress, making fuel quality and interval adherence critical.
Analysis derived from Alfa Romeo technical bulletins (2015–2020) and UK DVSA failure statistics (2020–2023). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about ALFA-ROMEO AR66303.
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Regulation (EC) No 715/2007
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