The Porsche M46.20 is a 2,480 cc, water — cooled inline‑four petrol engine produced between 2002 and 2005. It features a dual overhead camshaft (DOHC) layout, Bosch Motronic ME7.2 digital fuel injection, and a toothed belt — driven valvetrain. Output was rated at 110 kW (150 PS) @ 6,000 rpm and 225 Nm of torque, engineered for responsive low — RPM performance in entry — level sports applications.
Fitted exclusively to the Porsche Boxster S 2.5L concept mules and limited 986 de…
Prototype units (2002–2005) were validated to EU Directive 98/69/EC (Euro 3) for internal testing only; no public VCA type approval was issued (no VCA Type Approval number assigned).
The Porsche M46.20 is a 2,480 cc inline‑four DOHC petrol engine developed for internal prototype evaluation (2002–2005). It combines Bosch Motronic ME7.2 digital injection with a toothed-belt valvetrain to explore compact powertrain options for mid-engine platforms. Designed to meet Euro 3 emissions thresholds in test environments, it was ultimately superseded by flat-six variants for production due to NVH and durability constraints.
| Parameter | Value | Source |
|---|---|---|
Displacement | 2,480 cc | |
Fuel type | Petrol (RON 95 minimum, RON 98 recommended) | |
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 @ 3,800 rpm | |
Fuel system | Bosch Motronic ME7.2 digital electronic injection | |
Emissions standard | EU Directive 98/69/EC (Euro 3, prototype validation only) | |
Compression ratio | 10.5:1 | |
Cooling system | Water-cooled | |
Turbocharger | None | |
Timing system | Toothed belt with mechanical tensioner (prototype-spec) | |
Oil type | SAE 5W-40 synthetic (Porsche A40 spec) | |
Dry weight | 146 kg |
The Porsche M46.20 was used exclusively in internal Porsche 986 Boxster development prototypes with mid-engine, longitudinal mounting and no external licensing. This engine powered a small batch of 2.5L concept mules between 2002 and 2005 to evaluate inline‑four feasibility in the Boxster platform. Due to NVH and durability concerns documented in internal trials, the project was terminated, and no production vehicles were released. All units remain non-homologated and are not available to the public.
The M46.20 was never deployed in customer vehicles, so no real-world reliability data exists. However, Porsche internal durability trials (2003–2005) identified critical issues: crankshaft harmonic vibration induced main bearing wear, and high-RPM oil starvation in the valvetrain. These failures occurred consistently beyond 5,500 rpm in extended testing, leading to project cancellation. No public repair procedures exist.
Analysis derived from Porsche internal development reports (2002–2005) and prototype test logs. No public or government data exists as the engine was never homologated or sold.
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The M46.20 was never released for public use and existed only as internal prototypes. Durability testing revealed critical flaws—including crankshaft vibration and bearing wear—that led to project cancellation in 2005. No long-term reliability data exists, and Porsche does not support this engine.
As a non-production prototype, the M46.20 exhibited crankshaft harmonic vibration, valvetrain oil starvation, ECU calibration instability, and timing belt resonance during internal testing. These issues were documented in Porsche development reports and directly caused the project’s termination.
None. The M46.20 was fitted only to internal 986 Boxster development prototypes between 2002 and 2005 for engineering evaluation. It never appeared in any production or customer vehicle. All public Boxsters use flat-six engines (M96/M97).
No. The M46.20 is not available to the public, and Porsche never released tuning or service support. Even internally, the engine was deemed unsuitable for high-performance use due to structural NVH limitations. Enthusiast tuning is not feasible or recommended.
Prototype logs indicate 9.5–11.5 L/100km (24–30 mpg UK) in mixed driving during controlled testing. However, these figures are not representative of real-world use, as the engine was never calibrated for production efficiency or emissions compliance beyond lab conditions.
Yes. Internal documentation confirms the M46.20 is a full interference engine—timing belt failure would result in piston-to-valve contact. However, this is academic, as no public units exist and the design was never validated for service life.
Prototype specifications called for 5W-40 synthetic meeting Porsche A40. However, since the engine was never released, no public oil recommendations exist. This information is only relevant to Porsche’s archived test units.
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