The Porsche M48.50 Petrol is a 2,706 cc, water‑cooled flat‑six engine produced between 2005 and 2008. It featured a dual overhead cam (DOHC) per bank layout and Bosch Motronic ME7.8 electronic fuel injection, delivering 245 PS (180 kW) with 290 Nm of torque. The horizontally opposed cylinder design ensures a low centre of gravity—critical for the Cayman S and Boxster S’s balanced handling and responsive dynamics.
Fitted to the Porsche Cayman S (987) and Boxster S (987) variants, the M48.50 was engineered for high-revving performance with emphasis on throttle linearity, exhaust acoustics, and thermal stability. Emissions compliance in European markets was achieved through three-way catalytic converters and dual oxygen sensor feedback, allowing adherence to Euro 4 standards from launch.
One documented concern is rear main seal oil leaks due to crankshaft surface wear, highlighted in Porsche Technical Bulletin PTB/06/07. This issue stems from insufficient surface hardening on early crankshaft seals, exacerbated by high oil temperatures in mid-engine applications. In mid-2006, Porsche introduced a revised crankshaft with improved seal surface finish to reduce leakage rates under extended high-RPM operation.
All models (2005–2008) meet Euro 4 emissions standards in European markets (KBA Type Approval #KBA/987/4128).
The Porsche M48.50 Petrol is a 2,706 cc water‑cooled flat‑six engineered for mid‑engine sports roadsters and coupes (2005–2008). It combines Bosch Motronic ME7.8 electronic fuel injection with a DOHC 24-valve architecture to deliver linear power, strong mid-range torque, and high-revving character. Designed to meet Euro 4 emissions from launch, it balances performance with regulatory compliance through catalytic and closed-loop engine management.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 2,706 cc | |
| Fuel type | Petrol (Unleaded) | |
| Configuration | Flat‑6, DOHC per bank, 24‑valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 85.5 mm × 78.9 mm | |
| Power output | 245 PS (180 kW) | |
| Torque | 290 Nm @ 4,750 rpm | |
| Fuel system | Bosch Motronic ME7.8 electronic fuel injection | |
| Emissions standard | Euro 4 | |
| Compression ratio | 11.3:1 | |
| Cooling system | Water‑cooled (dual radiators with thermostatic control) | |
| Turbocharger | None | |
| Timing system | Chain‑driven DOHC (two chains per bank) | |
| Oil type | 10W‑60 semi‑synthetic (Porsche A40 spec) | |
| Dry weight | 165 kg |
The DOHC flat‑six provides high-revving responsiveness ideal for track-capable roadsters but requires strict adherence to oil change intervals and quality to prevent rear main seal degradation. Use of 10W-60 semi-synthetic oil meeting Porsche A40 spec is critical for high-temperature film strength and seal longevity. Cold starts below 5°C should be followed by 5–10 minutes of gentle warm-up. The ME7.8 system requires OEM-spec oxygen sensors and fuel pressure regulators—non-compliant parts cause mixture instability and catalytic converter damage. Early 2005–mid-2006 engines feature original-spec crankshafts prone to seal wear; post-mid-2006 units use revised surface-hardened crankshafts per Porsche bulletin PTB/06/07.
Oil Specs: Requires 10W-60 semi-synthetic oil meeting Porsche A40 specification (Porsche Tech Bulletin PTB/06/07). ACEA A3/B3 oils are insufficient for thermal stability.
Emissions: All M48.50 variants meet Euro 4 standards across all production years (2005–2008) as confirmed by KBA Type Approval #KBA/987/4128.
Power Ratings: Measured under DIN 70020 standards. Output requires 98 RON fuel and optimal catalytic converter function (Porsche TIS Doc. P987‑07B).
Porsche Technical Information System (TIS): Docs P987‑05A, P987‑05C, P987‑07B
KBA Type Approval Database (KBA/987/4128)
DIN 70020 Engine Power Measurement Standard
The Porsche M48.50 Petrol was used across Porsche's 987 platform with mid‑engine longitudinal mounting and no external licensing. This engine powered both the Boxster S and Cayman S with identical architecture, receiving a key internal update in mid-2006 with the introduction of a revised crankshaft seal surface finish, creating a critical service distinction. All adaptations are documented in OEM technical bulletins.
Engine code is stamped on the rear of the crankcase near the flywheel housing (Porsche TIS P987‑05A). The 7th–8th VIN digits are '98' for all 987 models; the 10th digit indicates model year. Early 2005–mid-2006 engines (VIN '5' and early '6') use original-spec crankshafts prone to rear seal leakage; late 2006–2008 (VIN '6' late, '7', '8') use revised surface-hardened crankshafts. The M48.50 can be visually distinguished from the base 2.7L M97/21 by black cam covers with ‘S’ badge and higher-flow intake manifolds. Engine serial number prefix '675.50' confirms displacement and variant.
The M48.50 Petrol's primary reliability risk is rear main seal oil leakage in early 2005–mid-2006 units, with elevated incidence in high-ambient-temperature or track use. Porsche internal durability reports from 2007 noted a significant share of early Boxster/Cayman S engines requiring rear seal replacement before 80,000 km under aggressive driving, while KBA field audits confirmed oil leaks as a common warranty claim in 2005–2006 production. Extended oil change intervals and incorrect viscosity reduce seal longevity, making oil quality and crankshaft condition critical.
Analysis derived from Porsche technical bulletins (2005–2008) and Kraftfahrt-Bundesamt (KBA) failure statistics (2006–2014). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about PORSCHE M-48-50.
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