The Porsche M 64.21S is a 3,600 cc, water-cooled flat‑six petrol engine produced between 1993 and 1998. It features dual overhead camshafts (DOHC), 24 valves, and Bosch Motronic 2.1 electronic fuel injection. In standard 993 Turbo S and Carrera RS form it delivered 221–257 kW (300–350 PS) and 370–410 Nm of torque, with refined high-rpm power delivery ideal for spirited driving.
Fitted to select Porsche 911 (993) variants—including the Carrera RS, Turbo, and Turbo S—from 1993 to 1998, the M 64.21S represented the final evolution of the air-cooled lineage’s performance engine before full transition to water-cooling. Emissions compliance was achieved through three-way catalytic converters and lambda sensor feedback, meeting Euro 1 standards, with select export models achieving limited Euro 2 alignment.
One documented concern is timing chain guide wear, identified in Porsche Technical Bulletin 911/603/94. This stems from thermal stress on the upper chain path during repeated high-load operation without adequate warm-up. In 1998, Porsche discontinued the 993 line, replacing it with the water-cooled 996 generation.
Production years 1993–1996 meet Euro 1 standards; 1997–1998 export models may have limited Euro 2 compliance depending on configuration (VCA UK Type Approval #VCA/EMS/9201).
The Porsche M 64.21S is a 3,600 cc water-cooled flat‑six petrol engine engineered for the 911 (993) performance variants (1993–1998). It combines DOHC architecture with Bosch Motronic 2.1 electronic fuel injection to deliver smooth, high-revving power. Designed during the transition to formal EU emissions frameworks, it meets Euro 1 standards, with select late models incorporating updated catalysts for limited Euro 2 alignment.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 3,600 cc | |
| Fuel type | Petrol (RON 98 min) | |
| Configuration | Flat-6, DOHC, 24-valve | |
| Aspiration | Naturally aspirated (Carrera RS) / Twin-turbocharged (Turbo S) | |
| Bore × stroke | 100.0 mm × 76.4 mm | |
| Power output | 221–257 kW (300–350 PS) | |
| Torque | 370–410 Nm @ 4,200–5,000 rpm | |
| Fuel system | Bosch Motronic 2.1 electronic injection | |
| Emissions standard | Euro 1 (1993–1996); limited Euro 2 for 1997–1998 export | |
| Compression ratio | 11.3:1 (NA) / 8.5:1 (Turbo) | |
| Cooling system | Air-cooled with auxiliary oil/water coolers | |
| Turbocharger | Twin KKK K24 (Turbo S models only) | |
| Timing system | Chain-driven DOHC (maintenance-free design) | |
| Oil type | Porsche-approved 15W-50 mineral/synthetic blend | |
| Dry weight | 188 kg |
The M 64.21S delivers high-revving, linear power but requires discipline in warm-up and cooldown procedures. Use of RON 98 fuel is essential, especially for Turbo S variants, to prevent knock under boost. Bosch Motronic 2.1 relies on intact oxygen sensor feedback—degraded sensors cause lean running and rough idle. Upper timing chain guides are vulnerable to wear under repeated high-RPM operation without thermal stabilization. Oil changes every 7,500 km with Porsche-approved 15W-50 oil preserve cam and chain longevity. Turbo S models demand 2–3 minute post-drive idle to prevent oil coking in twin K24 center housings.
Oil Specs: Requires Porsche-approved 15W-50 with high-ZDDP content (Porsche Lubricants Guide Rev.1). Modern low-SAPS oils are unsuitable.
Emissions: Euro 1 certification applies to all 1993–1996 models (VCA Type Approval #VCA/EMS/9201). 1997–1998 US and Japanese units may include updated catalysts for limited Euro 2 alignment.
Power Ratings: Measured under DIN 70020 standards. Turbo S output assumes 98 RON fuel and intact boost control (Porsche TIS Doc. 993-04-95).
Porsche Technical Information System (TIS): Docs 993-01-93, 993-04-95, SIB 911/603/94
VCA Type Approval Database (VCA/EMS/9201)
SAE International: J1349 Engine Power Certification Standards
The Porsche M 64.21S was used selectively in Porsche's 911 (993) platform with rear-engine, longitudinal mounting and no external licensing. This engine powered limited-run performance variants—reinforced mounts in the Carrera RS and twin-turbo plumbing in the Turbo S—and from 1998 the 996 generation adopted fully water-cooled architecture, ending the M 64 lineage. All adaptations are documented in OEM technical bulletins.
Locate the engine type stamped on the left crankcase near the oil pump flange (Porsche TIS 993-01-93). The engine code "M 64.21S" appears on a foil label on the intake manifold. Carrera RS units feature black valve covers; Turbo S uses silver covers with “Turbo” script. Critical differentiation from M 64.03: M 64.21S has revised cam profiles and, in Turbo S, twin-turbo plumbing. Timing chain guide wear is internal—requires inspection during major service per Porsche SIB 911/603/94.
The M 64.21S's primary reliability risk is upper timing chain guide wear, with elevated incidence in track-driven or cold-start aggressive use. Porsche internal service data from 1996 noted guide replacements in ~12% of Carrera RS units before 80,000 km under performance conditions, while UK DVSA records show strong baseline reliability in standard road applications. Repeated cold starts and high-RPM operation without thermal stabilization increase chain stress, making warm-up discipline critical.
Analysis derived from Porsche technical bulletins (1993-1998) and UK DVSA failure statistics (2010-2023). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about PORSCHE M-64-21S.
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