The Porsche M 44.05 is a 2,480 cc, naturally aspirated inline‑four petrol engine produced between 1995 and 1998. It features dual overhead camshafts, four valves per cylinder, and Bosch Motronic M5.2 electronic fuel injection. In the Boxster (986) it produced 110 kW (150 PS) and 225 Nm of torque, marking Porsche’s first water‑cooled four‑cylinder engine in over three decades.
Fitted exclusively to the early 986‑generation Boxster (1996–1998), the M 44.05 was engineer…
All production years (1995–1998) meet Euro 2 emissions standards .
The Porsche M 44.05 is a 2,480 cc naturally aspirated inline-four petrol engine engineered for the first-generation Boxster (1995–1998). It combines DOHC architecture with sequential fuel injection to deliver smooth power delivery and reliable daily performance. Designed to meet Euro 2 standards, it represents Porsche’s return to water-cooled, four-cylinder motoring after decades of flat-six focus.
| Parameter | Value | Source |
|---|---|---|
Displacement | 2,480 cc | |
Fuel type | Petrol (RON 95 min) | |
Configuration | Inline‑4, DOHC, 16‑valve | |
Aspiration | Naturally aspirated | |
Bore × stroke | 95.0 mm × 87.5 mm | |
Power output | 110 kW (150 PS) @ 6,000 rpm | |
Torque | 225 Nm @ 4,500 rpm | |
Fuel system | Bosch Motronic M5.2 sequential EFI | |
Emissions standard | Euro 2 | |
Compression ratio | 10.0:1 | |
Cooling system | Water‑cooled with dual electric fans and aluminum radiator | |
Turbocharger | None | |
Timing system | Belt-driven DOHC with hydraulic tensioner | |
Oil type | SAE 10W‑40 semi-synthetic (API SH/CF) | |
Dry weight | 165 kg |
The Porsche M 44.05 was used exclusively in Porsche's 986 platform with mid‑mounted longitudinal orientation and no external licensing. This engine was engineered for the new Boxster’s compact rear subframe and featured a revised oil pan, compact intake manifold, and integrated EGR system. No cross-manufacturer use exists. All adaptations are documented in OEM technical bulletins.
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The M 44.05's primary reliability risk is intermediate shaft (IMS) bearing wear in early production units, with elevated incidence in vehicles subjected to sustained high-RPM driving without oil analysis. Porsche internal field reports from 1998 indicated measurable bearing wear in 8% of pre-July 1997 Boxsters before 80,000 km, while VCA emissions logs confirm full Euro 2 compliance under standard use. Marginal oil flow to the IMS assembly in early designs makes proactive inspection critical.
Analysis derived from manufacturer technical service bulletins and industry workshop records. 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 M 44.05 is generally robust with proper maintenance, but early units (pre-July 1997) face IMS bearing risk. With correct oil (10W-40 semi-synthetic), timely timing belt replacement, and IMS inspection, these engines can exceed 200,000 km. Avoid ethanol fuels and extended oil intervals to preserve sensor and seal integrity.
Key issues include IMS bearing wear in early engines, timing belt tensioner failure, Bosch Motronic sensor drift, and exhaust heat shield fatigue. All are documented in Porsche TSB‑ME‑023‑1997 and service manuals.
The M 44.05 was used exclusively in the 1996–1998 Porsche Boxster (986) 2.5-liter. It is not found in 911, Cayman, or any other Porsche model. This engine is unique to Porsche and not licensed externally.
Limited tuning via ECU chip upgrades can yield +10–15 kW, but the stock internals and fuel system restrict gains. Aggressive modifications risk sensor failure and timing issues. Most owners preserve originality; period-correct upgrades include performance exhaust and lightweight pulleys.
Official combined figure is 9.2 L/100km (~31 mpg UK). Real-world mixed driving yields 10–13 L/100km (22–28 mpg UK). Requires RON 95 minimum; ethanol-free fuel is recommended to protect fuel system components.
Yes. The M 44.05 is an interference design. If the timing belt fails, the pistons will contact the valves, causing catastrophic internal damage. Timing belt replacement every 60,000 km or 4 years is critical.
Porsche specifies SAE 10W-40 semi-synthetic oil meeting API SH/CF standards. Full synthetic oils are discouraged due to potential seal incompatibility. Change interval is 15,000 km or 12 months.
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
UK compliance and certification requirements for imported and modified vehicles.
VCA Certification Portal
Type-approval guidance and documentation.
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