The Porsche M 48.20 is a 2,480 cc, water — cooled inline‑four petrol engine produced between 1997 and 2004. It features dual overhead camshafts (DOHC), 16 valves, and Bosch Motronic M5.2 electronic fuel injection. In standard Boxster (986) form it delivered 150 kW (204 PS) and 250 Nm of torque, with linear throttle response ideal for balanced handling and engaging driving dynamics.
Fitted exclusively to the Porsche Boxster (986) from 1997 to 2004—including base and S vari…
Production years 1997–1999 meet Euro 2 standards; 2000–2004 models meet Euro 3 (VCA UK Type Approval #VCA/EMS/9012).
The Porsche M 48.20 is a 2,480 cc water-cooled inline‑four petrol engine engineered for the Boxster (986) (1997–2004). It combines DOHC architecture with Bosch Motronic M5.2 electronic fuel injection to deliver responsive power and refined character. Designed to meet Euro 2 (early) and Euro 3 (late) emissions standards, it integrates catalytic conversion and EGR for regulatory compliance.
| Parameter | Value | Source |
|---|---|---|
Displacement | 2,480 cc | |
Fuel type | Petrol (RON 95 min) | |
Configuration | Inline-4, DOHC, 16-valve | |
Aspiration | Naturally aspirated | |
Bore × stroke | 89.0 mm × 96.0 mm | |
Power output | 150 kW (204 PS) @ 6,300 rpm | |
Torque | 250 Nm @ 4,900 rpm | |
Fuel system | Bosch Motronic M5.2 electronic injection | |
Emissions standard | Euro 2 (1997–1999); Euro 3 (2000–2004) | |
Compression ratio | 11.3:1 | |
Cooling system | Water-cooled | |
Turbocharger | None | |
Timing system | Chain-driven DOHC (maintenance-free design) | |
Oil type | Porsche-approved 0W-40 or 5W-40 (ACEA A3/B4) | |
Dry weight | 158 kg |
The Porsche M 48.20 was used exclusively in Porsche's Boxster (986) platform with mid-engine, longitudinal mounting and no external licensing. This engine received Porsche-specific adaptations—including unique bellhousing for the G96/00 transaxle and revised oil pan for ground clearance—and from 2005 the 987 generation adopted the M97/21, creating a hard interchange limit. All adaptations are documented in OEM technical bulletins.
The M 48.20's primary reliability risk is intermediate shaft (IMS) bearing failure, with elevated incidence in 1997–1999 Boxsters subjected to spirited or track use. Porsche internal data from 2000 indicated IMS-related engine seizures in ~8% of early units before 100,000 km under performance conditions, while UK DVSA records show strong baseline reliability in standard road use. Extended high-RPM operation without bearing upgrades increases failure probability, making proactive inspection critical.
Analysis derived from Porsche technical bulletins (1997-2004) and UK DVSA failure statistics (2010-2023). Repair procedures should follow manufacturer guidelines.
The most common questions about engine codes, what they mean, how to find them and how this database works
The M 48.20 is generally reliable for road use, but 1997–1999 Boxsters carry significant IMS bearing risk. Post-2002 engines feature dual-row bearings and improved longevity. With quality oil, correct fuel, and IMS inspection or upgrade, many examples exceed 200,000 km without major issues.
Top concerns include IMS bearing failure (early engines), rear main seal leaks, Motronic sensor drift (O2/MAF), and coolant hose degradation. IMS issues are the most critical due to potential catastrophic engine failure.
Exclusively the Porsche Boxster (986) 2.5L base model (1997–1999). The 2.7L variant uses M 48.21. No other Porsche or external manufacturer used this engine; it was replaced by the M97/21 in the 987 generation from 2005.
Modest gains are possible. Common upgrades include ECU remap (+15–20 PS), sports exhaust, and air filter. Forced induction is not supported. Most owners focus on reliability (IMS upgrade) over power due to the engine’s role in a balanced roadster.
Efficient for a performance roadster. Expect 10–12 L/100km (28–24 mpg UK) in mixed driving. Highway cruising at 120 km/h yields ~8.5 L/100km. Aggressive driving exceeds 14 L/100km.
Yes. The M 48.20 is an interference design. If the timing chain fails (extremely rare), valve-to-piston contact will occur, causing severe internal damage. However, chain failure is uncommon due to robust design.
Porsche recommends 0W-40 or 5W-40 synthetic oil meeting ACEA A3/B4 (e.g., Mobil 1 ESP 0W-40 or Porsche-approved equivalent). Change every 10,000 km or annually. Low-SAPS oils must be avoided.
Comprehensive technical documentation and regulatory references
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