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 publicissued (noassigned).
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 Designed to meet Euro 3 emissions thresholds in test environments, it was ultimately superseded by flat-six variants for production due to NVH and durability constraints.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 | Refer to vehicle handbook / manufacturer specification | |
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.
Engine Finders UK Ltd, which operates EngineCode.uk, can pass your enquiry to engine suppliers in the UK. The service is for vehicles in the United Kingdom, with UK delivery or fitting. This is a commercially connected service, and sending an enquiry does not confirm diagnosis or compatibility.
Diagnostic reminder: If a technician has recommended replacing the engine, you can send an enquiry to engine suppliers in the UK. Confirm the diagnosis first: an engine-code record does not diagnose a fault.
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.
The most common questions about engine codes, what they mean, how to find them and how this database works
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.
Comprehensive technical documentation and regulatory references
EngineCode.uk is operated by Engine Finders UK Ltd. It provides engine-reference information and an optional commercial enquiry service. It is not an official manufacturer website. Check the record's sources and confirm vehicle-specific details before relying on it for parts, repairs or replacement.
Our editorial standard prioritises relevant manufacturer documentation and official regulatory sources. The sources and verification status for a record should be checked alongside the data.
A statement is not verified merely because a source is listed. Where supporting evidence is missing or conflicting, the record should identify that limitation. Please report unsupported or inconsistent information.
Transparency in gaps
A missing or unverified value does not mean the manufacturer has withheld it. We distinguish information not yet verified, information not available to us, and information explicitly not disclosed by the source.
Regulatory Stability
EU regulations are referenced using CELEX identifiers for long-term stability.
EUR-Lex
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.
Records are subject to review and correction. Source links, dates and verification notes should be read with the technical information. Our Editorial and Sourcing Policy explains our standards and review process.
Found an error or missing source? Report a problem with this page. Include the field or statement concerned and a supporting source if available. You can also email corrections@enginecode.uk.
Copyright and permissions
Images and other material may be protected by copyright. Attribution does not by itself grant permission to reuse material. If you believe material on this site infringes your rights, contact copyrights@enginecode.uk with the page URL and details of your claim. We will review the material and take appropriate action.
Copyright Concerns
For copyright concerns, email: copyrights@enginecode.uk
Our Privacy Policy explains how Engine Finders UK Ltd uses information from visits, vehicle lookups, enquiries and messages. Our Cookie Policy explains cookies and similar technologies and how to change your choices.
For access, correction, or deletion requests, email: gdpr@enginecode.uk
Trademark Notice
All trademarks, logos, and engine codes are the property of their respective owners. Use on this site is strictly for reference and identification.
Ownership and commercial services
EngineCode.uk is owned and operated by Engine Finders UK Ltd. Alongside our reference content, we offer an optional replacement-engine enquiry service through Engine Finders and may identify relevant services provided by businesses connected with us. These commercial connections are disclosed. Using an enquiry service is not required to read our reference content.
Engine Finders UK Ltd operates this website. Our optional enquiry service has a commercial purpose. Our Ownership and Commercial Disclosure explains the relationship between the reference website and that service. Participating suppliers pay a fee or subscription to participate on the network and receive quote requests.
Use this record as a starting point for identification. Specifications and vehicle applications may contain errors or omissions. Confirm the exact engine variant and compatibility using vehicle-specific documentation and a qualified supplier or technician.
All external links open in new tabs. Please verify current availability of resources.