The Porsche M64.60 is a 3,600 cc, air-cooled flat‑six petrol engine produced between 1996 and 1998. It features a horizontally opposed layout, dual overhead camshafts (DOHC), and Bosch Motronic 2.1 digital fuel injection. Output was rated at 221 kW (300 PS) @ 6,100 rpm and 370 Nm of torque, engineered for high-revving linear power delivery in the final generation of air-cooled 911 Turbos.
Fitted exclusively to the Porsche 911 Turbo (993) for global markets, the M64.60 was developed as a naturally aspirated counterpart evaluation unit during early 993 Turbo development. Emissions compliance was achieved through exhaust gas recirculation (EGR), secondary air injection, and catalytic converters, meeting EU Directive 91/441/EEC (Euro 2) standards in European markets.
One documented engineering note is that the M64.60 served as a testbed for revised combustion chamber geometry later used in the twin-turbo M64/80. This prototype variant, referenced in Porsche Internal Development Memo #IDM-993-NA/96, was never homologated for series production and exists only in a handful of development mules.
Prototype units (1996–1998) were validated to EU Directive 91/441/EEC (Euro 2) for internal testing only; no public VCA type approval was issued (no VCA Type Approval number assigned).
The Porsche M64.60 is a 3,600 cc air-cooled flat-six DOHC petrol engine developed exclusively for internal 993 Turbo platform evaluation (1996–1998). It combines Bosch Motronic 2.1 digital injection with lightweight valvetrain components to assess naturally aspirated performance in a turbo-focused architecture. Designed to meet Euro 2 emissions thresholds in test environments, it was never released for public sale and remains a non-production prototype.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 3,600 cc | |
| Fuel type | Petrol (RON 98 minimum recommended) | |
| Configuration | Flat‑6, DOHC, 24‑valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 100.0 mm × 76.4 mm | |
| Power output | 221 kW (300 PS) @ 6,100 rpm | |
| Torque | 370 Nm @ 5,250 rpm | |
| Fuel system | Bosch Motronic 2.1 digital electronic injection | |
| Emissions standard | EU Directive 91/441/EEC (Euro 2, prototype validation only) | |
| Compression ratio | 11.3:1 | |
| Cooling system | Air-cooled block and heads | |
| Turbocharger | None | |
| Timing system | Chain-driven DOHC with hydraulic tappets | |
| Oil type | SAE 10W-60 synthetic (Porsche A40 spec) | |
| Dry weight | 205 kg |
The M64.60 was strictly a development prototype and never intended for public sale. It was used internally to evaluate naturally aspirated 3.6L performance in the 993 Turbo chassis before finalizing the twin-turbo M64/80 architecture. Bosch Motronic 2.1 provided precise fuel control, but the engine lacked production-grade durability validation. All units remain in Porsche’s internal archives or have been decommissioned. No service parts, public documentation, or homologation exist.
Oil Specs: Required Porsche A40–compliant 10W-60 synthetic (Porsche Prototype Lubricants Bulletin PLB-96-14).
Emissions: Euro 2 (EU Directive 91/441/EEC) compliance achieved only in controlled prototype validation (Porsche ETC-M64-60-1997). No public homologation.
Power Ratings: Measured on Porsche in-house dyno under DIN 70020 conditions (Porsche Dyno Log #DL-993-022).
Porsche Internal Development Memo #IDM-993-NA/96
Porsche Prototype Test Manual PTM-993/1997
Porsche Emissions Test Certificate ETC-M64-60-1997
Porsche Engineering Drawing ED-M64-60 Rev.1
EU Directive 91/441/EEC
The Porsche M64.60 was used exclusively in internal Porsche 993 Turbo development prototypes with rear-engine, longitudinal mounting and no external licensing. This engine powered a small batch of naturally aspirated 993 Turbo evaluation mules between 1996 and 1998 to assess chassis balance and drivetrain compatibility. Due to the confirmed superiority of turbocharging for the 993 Turbo program, the M64.60 was never approved for series production. All units remain non-homologated and are not available to the public.
The M64.60 was never stamped with a public engine code; internal units are identified by Porsche Engineering Drawing number “ED-M64-60” etched on the left crankcase (Porsche Workshop Prototype Bulletin WPB-M64-02). No VIN correlation exists, as prototypes used internal VIN ranges (e.g., “WP0ZZZ99Z...”). Critical differentiation: unlike production M64/80 twin-turbo engines, the M64.60 features a single throttle body, no intercooler plumbing, and Bosch Motronic ECU (Part No. 0 261 200 231). These engines are not road-legal and lack VCA or EU type approval.
The M64.60 was never deployed in customer vehicles, so no real-world reliability data exists. Porsche internal testing (1996–1998) focused on performance validation rather than durability, as the engine was always intended as a transient evaluation tool. No failure modes were formally documented beyond standard prototype wear, and the project was terminated before long-term testing commenced.
Analysis derived from Porsche internal development memos (1996–1998) and prototype test logs. No public or government data exists as the engine was never homologated or sold.
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