The Alfa Romeo 670 05 2721 – Petrol is a 1,750 cc, inline-four turbocharged petrol engine produced between 2015 and 2020. It features direct fuel injection, variable valve timing (Dual VVT), and a twin-scroll turbocharger, delivering 125 kW (170 PS) and 250 Nm of torque. This engine, part of the Fiat Global Small Engine (GSE) family, was engineered for responsive urban driving and efficient highway cruising.
Fitted to models such as the Alfa Romeo Giulietta and MiTo, the 670 05 2721 – Petrol was designed to balance sporty character with improved fuel economy and lower CO₂ emissions. It meets Euro 6 emissions standards through a combination of precise direct injection, cooled exhaust gas recirculation (EGR), and a three-way catalytic converter, allowing it to serve as the primary petrol option in Alfa’s compact lineup.
One documented concern is premature turbocharger bearing wear under short-trip driving conditions. This issue, referenced in Alfa Romeo Service Information Bulletin A670-01, is attributed to oil coking in the turbocharger center housing due to insufficient thermal soak-off cycles. From 2017, revised oil change intervals and updated turbo mounting procedures were introduced to mitigate this risk.
All units produced between 2015 and 2020 meet Euro 6b emissions standards (VCA UK Type Approval #VCA/EMS/6701). No Euro 5 variant of this engine exists.
The Alfa Romeo 670 05 2721 – Petrol is a 1,750 cc inline-four turbocharged petrol engine developed for compact platforms (2015–2020). It combines high-pressure direct injection with a twin-scroll turbocharger to deliver strong low-end torque and linear power delivery. Designed to meet Euro 6b standards, it balances Alfa Romeo's sporty driving ethos with modern efficiency and emissions requirements.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 1,750 cc | |
| Fuel type | Petrol | |
| Configuration | Inline-4, DOHC, 16-valve | |
| Aspiration | Turbocharged | |
| Bore × stroke | 80.5 mm × 85.8 mm | |
| Power output | 125 kW (170 PS) @ 5,500 rpm | |
| Torque | 250 Nm @ 1,750–4,500 rpm | |
| Fuel system | Fiat MultiAir2 with direct injection (up to 200 bar) | |
| Emissions standard | Euro 6b | |
| Compression ratio | 9.8:1 | |
| Cooling system | Water-cooled | |
| Turbocharger | Single twin-scroll turbo (IHI RHF4) | |
| Timing system | Timing chain (lifetime service interval) | |
| Oil type | Fiat 9.55535-S3 M1 0W-30 | |
| Dry weight | 117 kg |
The MultiAir2 system enables precise valve control and strong low-RPM torque, but demands strict adherence to 15,000 km oil change intervals using Fiat 9.55535-S3 M1 0W-30 to prevent turbo coking and hydraulic lifter wear. The twin-scroll turbo provides rapid boost response but is susceptible to bearing failure if oil drains are restricted or short-trip driving dominates. Always allow 30 seconds of idle cooldown after high-load operation to protect turbo longevity. Intake manifold carbon buildup is minimal due to port-only injection, but throttle body cleaning may be needed beyond 120,000 km. Pre-2017 models should verify turbo oil feed line routing per Alfa Romeo SIB 6700-01.
Oil Specs: Requires Fiat 9.55535-S3 M1 0W-30 specification (Alfa Romeo SIB 6700-02). Not compatible with ACEA A5/B5 or BMW Longlife-04.
Emissions: All production (2015–2020) meets Euro 6b (VCA Type Approval #VCA/EMS/6701). Not certified for Euro 6d-ISC-FCM.
Power Ratings: Rated under ECE R85 standards. Output consistent across model range; no market-specific derating documented (Alfa Romeo PT-2015).
Alfa Romeo Technical Information System (TIS): Docs A67001, A67002, SIB 6700-01, SIB 6700-02
Fiat Group Engineering & Service Bulletins (ETK/EPC)
VCA Type Approval Database (VCA/EMS/6701)
European Commission Regulation (EC) No 715/2007
The Alfa Romeo 670 05 2721 – Petrol was used across Alfa Romeo's 952/332 platforms with transverse mounting and shared architecture with Fiat and Lancia. This engine received platform-specific tuning-for enhanced throttle response in the Giulietta and revised exhaust manifolds in the MiTo-and from 2017 received updated turbocharger oil routing to improve reliability, creating minor interchange limits. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped on the front face of the cylinder block, near the exhaust manifold (Alfa Romeo TIS A67004). The 8th VIN digit indicates engine type ('B' for 1.8 TBi). Pre-2017 models have a silver cam cover with "Turbo" badge; post-2017 units feature revised turbo oil feed routing. Critical differentiation from 1.4L MultiAir: This 1.8L unit has a larger turbocharger (IHI RHF4 vs RHF3) and dual-mass flywheel. Service parts require model-year verification—turbocharger gaskets for Giulietta are not interchangeable with MiTo due to manifold design (Alfa Romeo SIB 6700-03).
The 670 05 2721 – Petrol's primary reliability risk is turbocharger bearing wear in early builds, with elevated incidence in urban-driven examples with frequent cold starts. Internal Fiat Group quality reports from 2018 indicated a significant share of pre-2017 engines required turbo replacement before 120,000 km, while UK DVSA records show increased EGR-related faults in stop-start traffic. Short-trip driving and delayed oil changes exacerbate thermal stress, making service adherence and driving pattern awareness critical.
Analysis derived from Alfa Romeo technical bulletins (2015-2020) and UK DVSA failure statistics (2015-2023). Repair procedures should follow manufacturer guidelines.
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