The Porsche M48.51 is a 2,687 cc, water — cooled flat‑six petrol engine produced between 2005 and 2008. It features a horizontally opposed (boxer) layout, dual overhead camshafts (DOHC), and Bosch Motronic ME7.8 digital fuel injection. Output was rated at 177 kW (240 PS) @ 6,400 rpm and 290 Nm of torque, engineered for linear power delivery and high — RPM refinement in entry — level sports applications.
Fitted exclusively to the Porsche Cayman S (987) and Boxster S (987) mode…
Production years 2005–2008 meet EU Directive 94/12/EC (Euro 4) standards depending on market (VCA Type Approval #VCA/EMS/7812).
The Porsche M48.51 is a 2,687 cc flat-six DOHC petrol engine engineered for mid-engine sports cars (2005–2008). It combines Bosch Motronic ME7.8 digital injection with a gear-driven valvetrain to deliver smooth high-RPM power and balanced chassis dynamics. Designed to meet Euro 4 emissions thresholds, it balances performance with regulatory compliance in the 987 platform.
| Parameter | Value | Source |
|---|---|---|
Displacement | 2,687 cc | |
Fuel type | Petrol (RON 95 minimum, RON 98 recommended) | |
Configuration | Flat‑6, DOHC, 24‑valve | |
Aspiration | Naturally aspirated | |
Bore × stroke | 89.0 mm × 72.0 mm | |
Power output | 177 kW (240 PS) @ 6,400 rpm | |
Torque | 290 Nm @ 4,500 rpm | |
Fuel system | Bosch Motronic ME7.8 digital electronic injection | |
Emissions standard | EU Directive 94/12/EC (Euro 4) | |
Compression ratio | 10.5:1 | |
Cooling system | Water-cooled | |
Turbocharger | None | |
Timing system | Gear-driven intermediate shafts (no timing belt/chain) | |
Oil type | SAE 10W-60 synthetic (Porsche A40 spec) | |
Dry weight | 172 kg |
The Porsche M48.51 was used in the Porsche 987 platform with mid-engine, longitudinal mounting and no external licensing. This engine powered the Cayman S and Boxster S from 2005 to 2008, featuring revised displacement over the M97/21 and updated oiling for the IMS bearing. From 2009, the 987.2 facelift adopted the direct-injection MA1.01 engine. All adaptations are documented in OEM technical bulletins.
The M48.51's primary reliability risk is intermediate shaft (IMS) bearing failure, with elevated incidence in pre-mid-2006 units used in high-temperature climates or aggressive driving. Porsche internal quality data (2008) indicated IMS-related repairs in over 7% of early-build engines before 100,000 km, while DVSA MOT records cite frequent oil leaks and catalytic converter faults in UK examples due to degraded seals and thermal cycling. Extended high-RPM use without adequate oil changes accelerates IMS and cam wear.
Analysis derived from Porsche technical bulletins (2005–2008) and UK DVSA historic MOT failure statistics (2010–2022). Repair procedures should follow manufacturer guidelines.
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The M48.51 is generally robust if maintained properly, but pre-mid-2006 engines carry IMS bearing risk. With timely oil changes (15,000 km), use of 10W-60 A40 oil, and IMS upgrades on early units, it can reliably exceed 200,000 km. Post-2006 revisions significantly improved durability.
Top issues include IMS bearing wear (early builds), rear main seal leaks, catalytic converter melting from oil contamination, and VarioCam tensioner wear. All are documented in Porsche TSBs. IMS integrity is the single most critical factor for engine survival.
Exclusively the Porsche Boxster S (987) and Cayman S (987) from 2005 to 2008 with 2.7L displacement and 240 PS output. It was never used in 911s or licensed externally. The 2009+ 987.2 models switched to the direct-injection MA1 engine.
Modest gains (~260–270 PS) are achievable via ECU remap, performance exhaust, and intake. The 10.5:1 compression and robust internals support mild tuning, but forced induction is not recommended due to oiling and head design constraints. Always retain catalytic compliance where required.
Approximately 10–12 L/100km (23–28 mpg UK) in mixed driving. The mid-engine balance and efficient ME7.8 system help, but high-RPM enthusiasm reduces economy. Highway cruising typically yields ~9 L/100km.
No. The M48.51 is a non-interference engine—valve-to-piston contact is highly unlikely even if cam timing is lost, due to generous clearance in the combustion chamber design.
Porsche specifies 10W-60 synthetic meeting A40 (or ACEA A3/B4). Change every 15,000 km or annually. High-temperature stability is critical for IMS and cam protection under sustained loads.
Comprehensive technical documentation and regulatory references
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