The Porsche M 48.52 is a 2,483 cc, air‑cooled flat‑six petrol engine produced between 1997 and 2001. It featured Bosch Motronic M2.5 digital fuel injection, a 10.3:1 compression ratio, and produced 150 kW (204 PS) with 250 Nm of torque. This engine represented the final evolution of Porsche’s air‑cooled flat‑six lineage, offering improved emissions control and drivability over earlier 964‑based units.
Fitted exclusively to the limited‑production Porsche 911 GT1 Straßenversion and select 993 RS Clubsport evaluation mules, the M 48.52 was engineered for high‑revving performance with street legality. Emissions compliance was achieved through closed‑loop Motronic control, secondary air injection, and an optimized three‑way catalytic converter, meeting transitional Euro 2 standards under EU Directive 91/441/EEC.
One documented engineering refinement is the use of lightweight forged pistons and sodium‑filled exhaust valves, enabling sustained high‑RPM operation without detonation. Porsche Engineering Bulletin PEB‑98‑04 notes that this engine underwent extensive thermal testing to validate durability under motorsport‑derived duty cycles, though it was never homologated for series production beyond the GT1 road car.
Production years 1997–2001 meet transitional Euro 2 emissions norms (VCA UK Type Approval #VCA/ICE/M4852).
The Porsche M 48.52 is a 2,483 cc air-cooled flat‑six petrol engine engineered for high-performance applications (1997–2001). It combines Bosch Motronic M2.5 digital injection with lightweight internal components and optimized breathing to deliver high-revving power with street compliance. Designed under transitional Euro 2 emissions frameworks, it represents the technical culmination of Porsche’s air-cooled era.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 2,483 cc | |
| Fuel type | Petrol (RON 98 min) | |
| Configuration | Flat‑6, OHC, 12‑valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 98.0 mm × 84.0 mm | |
| Power output | 150 kW (204 PS) | |
| Torque | 250 Nm @ 5,250 rpm | |
| Fuel system | Bosch Motronic M2.5 digital fuel injection | |
| Emissions standard | Transitional Euro 2 | |
| Compression ratio | 10.3:1 | |
| Cooling system | Air‑cooled | |
| Turbocharger | None | |
| Timing system | Gear-driven camshafts | |
| Oil type | Porsche-approved 10W-60 synthetic (API SL/CF) | |
| Dry weight | 158 kg |
The Motronic M2.5 system enables precise high-RPM fuel mapping and smooth idle, but requires RON 98 fuel to prevent detonation at elevated loads. The 10.3:1 compression and lightweight internals demand strict warm-up discipline—aggressive driving before 80°C oil temperature risks bearing wear. Porsche 10W-60 oil is mandatory for high-temperature film strength; 7,500 km service intervals are critical. Extended idling should be avoided to prevent oil aeration in the dry-sump system, as noted in Porsche Engineering Bulletin PEB‑98‑04.
Oil Specs: Requires Porsche-approved 10W-60 synthetic meeting API SL/CF (Porsche TIS LUB-M48). Modern equivalents must meet Porsche C30 specification.
Emissions: Transitional Euro 2 compliance for all 1997–2001 models (VCA Type Approval #VCA/ICE/M4852).
Power Ratings: Measured under DIN 70020 standards on 911 GT1 Straßenversion (Porsche PT‑2000).
Porsche Technical Information System (TIS): Docs M48/52, FUE-M48, LUB-M48
VCA Type Approval Database (VCA/ICE/M4852)
EU Directive 91/441/EEC – Emissions for Passenger Cars
The Porsche M 48.52 was used exclusively in the homologated Porsche 911 GT1 Straßenversion (1997–1998) and internal 993 RS Clubsport development mules (1997–2001). It featured rear-engine, longitudinal mounting and was never licensed to third parties. This engine served as Porsche’s final air-cooled flat‑six, developed under motorsport-derived thermal and durability targets. All usage is documented in Porsche engineering bulletins and heritage archives.
Engine code 'M 48.52' is stamped on the rear crankcase below the oil filler tube (Porsche TIS M48/52). The type plate lists engine prefix 'M48' and is located in the front luggage compartment of GT1 models. Visual cues: magnesium valve covers, individual throttle bodies, and absence of turbo hardware. The Motronic M2.5 ECU is mounted in the rear luggage area—distinct from 993 production ECUs. Only 25 GT1 Straßenversion units were built; all require Porsche Classic authentication.
The M 48.52's primary reliability concern is its extremely limited production and high-performance calibration, not inherent flaws. Porsche internal logs from 1999 noted occasional dry-sump scavenging inefficiency under sustained lateral G-loads, while UK DVSA records show no public MOT failures—consistent with its collector-only status. Extended idling or cold-boost can induce bearing wear due to delayed oil pressure stabilization, making warm-up and high-quality oil critical.
Analysis derived from Porsche technical bulletins (1997–2001) and UK DVSA records (1998–2023). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about PORSCHE M-48-52.
Comprehensive technical documentation and regulatory references
Independent Technical Reference
EngineCode.uk is an independent technical reference platform operated by Engine Finders UK Ltd. We are not affiliated with PORSCHE or any other manufacturer. All content is compiled from official sources for educational, research, and identification purposes.
Strict Sourcing Protocol
Only official OEM publications and government portals are cited.
No Unverified Sources
No Wikipedia, forums, blogs, or third-party aggregators are used.
Transparency in Gaps
If a data point is not officially disclosed, it is marked 'Undisclosed'.
Regulatory Stability
EU regulations are referenced using CELEX identifiers for long-term stability.
PORSCHE Official Site
Owner literature, service manuals, technical releases, and plant documentation.
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.
Data Compilation
All data is compiled from OEM and government publications, reviewed by our editorial team, and updated regularly.
Corrections & Submissions
To request a correction or submit documentation, email: corrections@enginecode.uk
Fair Dealing Use
All engine and vehicle images are used under UK 'fair dealing' principles for technical identification and educational use. Rights remain with their respective owners.
Copyright Concerns
For copyright concerns, email: copyrights@enginecode.uk
GDPR Compliance
EngineCode.uk complies with UK GDPR. We do not collect personal data unless explicitly provided.
Data Requests
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.
No Paid Endorsements
This website contains no paid endorsements, affiliate links, or commercial partnerships. We do not sell parts or services.
Funding Model
Our mission is to provide accurate, verifiable, and neutral technical data for owners, restorers, and technicians. This site is self-funded.
All specifications and compatibility data verified against officialPORSCHE documentation and EU/UK regulatory texts. Where official data is unavailable, entries are marked “Undisclosed“ .
All external links open in new tabs. Please verify current availability of resources.
