The Porsche M 96.70 is a 3,179 cc, water-cooled flat‑six petrol engine produced between 1996 and 1998. It features dual overhead camshafts (DOHC), 24 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 smooth mid-range delivery and refined high-revving character ideal for agile roadster dynamics.
Fitted exclusively to the Porsche Boxster (986) from 1996 to 1998—including base models in global markets—the M 96.70 marked Porsche’s debut of water-cooled architecture in a production roadster. Emissions compliance was achieved through twin catalytic converters and exhaust gas recirculation (EGR), meeting Euro 2 standards across all markets.
One documented concern is intermediate shaft (IMS) bearing wear, highlighted in Porsche Technical Bulletin 986/602/99. This stems from marginal oil flow to the single-row IMS bearing under sustained high-RPM operation, particularly in early production units. In 1999, Porsche upgraded bearing design and introduced the M 96.71 with revised displacement.
Production years 1996–1998 meet Euro 2 standards (VCA UK Type Approval #VCA/EMS/9401). No Euro 3 variants were produced for this engine family.
The Porsche M 96.70 is a 3,179 cc water-cooled flat‑six petrol engine engineered for the Boxster (986) (1996–1998). It combines DOHC architecture with Bosch Motronic M5.2 electronic fuel injection to deliver responsive power and balanced torque. Designed to meet Euro 2 emissions standards, it integrates twin catalytic converters and EGR for full regulatory compliance.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 3,179 cc | |
| Fuel type | Petrol (RON 95 min) | |
| Configuration | Flat-6, DOHC, 24-valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 89.0 mm × 85.0 mm | |
| Power output | 150 kW (204 PS) @ 6,200 rpm | |
| Torque | 250 Nm @ 4,700 rpm | |
| Fuel system | Bosch Motronic M5.2 electronic injection | |
| Emissions standard | Euro 2 | |
| Compression ratio | 10.5:1 | |
| Cooling system | Water-cooled (dual-circuit) | |
| Turbocharger | None | |
| Timing system | Chain-driven DOHC (maintenance-free design) | |
| Oil type | Porsche-approved 10W-40 or 5W-40 (ACEA A3/B4) | |
| Dry weight | 155 kg |
The M 96.70 offers smooth, linear power well-suited to the Boxster’s handling balance but requires vigilance on IMS bearing health. Use of RON 95 fuel is sufficient; RON 98 improves combustion smoothness under load. Oil changes every 10,000 km with Porsche-approved 10W-40 or 5W-40 ACEA A3/B4 oil help maintain bearing and cam longevity. Bosch Motronic M5.2 demands intact oxygen sensor feedback—degraded sensors cause lean running and rough idle. Pre-1999 engines should be inspected for IMS condition or upgraded per Porsche SIB 986/602/99.
Oil Specs: Requires ACEA A3/B4–compliant synthetic 10W-40 or 5W-40 (Porsche Lubricants Guide Rev.1). Low-SAPS oils are unsuitable.
Emissions: Euro 2 certification applies to all 1996–1998 M 96.70 units (VCA Type Approval #VCA/EMS/9401). No Euro 3 compliance was implemented for this engine.
Power Ratings: Measured under DIN 70020 standards. Output assumes functional catalytic converters and intact fuel trim (Porsche TIS Doc. 986-02-97).
Porsche Technical Information System (TIS): Docs 986-01-96, 986-02-97, SIB 986/602/99
VCA Type Approval Database (VCA/EMS/9401)
SAE International: J1349 Engine Power Certification Standards
The Porsche M 96.70 was used exclusively in Porsche's Boxster (986) platform with mid-engine, longitudinal mounting and no external licensing. This engine powered early base models with revised oil pan for ground clearance and unique accessory drives—and from 1999 the M 96.71 (2.7L) replaced it, creating a hard interchange limit. All adaptations are documented in OEM technical bulletins.
Locate the engine type stamped on the rear crankcase near the flywheel housing (Porsche TIS 986-01-96). The engine code "M 96.70" appears on a foil label on the intake manifold. All units feature black DOHC valve covers with “16V” script and cam position sensor on the exhaust cam. Critical differentiation from M 96.71: M 96.70 has 89.0 mm bore and 3.2L displacement; M 96.71 uses 91.0 mm bore (2.7L). IMS bearing condition cannot be visually verified—requires borescope or disassembly per Porsche SIB 986/602/99.
The M 96.70's primary reliability risk is IMS bearing failure, with elevated incidence in high-mileage or spirited examples. Porsche internal service data from 1998 indicated IMS-related engine seizures in ~9% of early Boxsters before 90,000 km under performance use, while UK DVSA records show strong baseline reliability in standard road applications. Extended high-RPM operation without warm-up increases thermal stress on the bearing, making proactive inspection critical.
Analysis derived from Porsche technical bulletins (1996-1998) and UK DVSA failure statistics (2010-2023). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about PORSCHE M-96-70.
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