The Porsche 911.47 is a 2,341 cc, air‑cooled flat‑six petrol engine produced between 1969 and 1973. It features a single overhead camshaft per bank (SOHC), mechanical fuel injection (Bosch K — Jetronic precursor), and delivers 125 kW (170 PS) at 6,300 rpm with 206 Nm of torque. This enlarged — displacement variant improved drivability and thermal stability over earlier 2.2L units.
Fitted exclusively to the Porsche 911 E and 911 S models (internal code 911/930), the 911.47…
Production years 1969–1973 predate EU emissions standards; vehicles are exempt from modern type approval (VCA Historic Vehicle Exemption #VCA/HV/91147).
The Porsche 911.47 is a 2,341 cc air‑cooled flat‑six petrol engine engineered for rear‑mounted sports cars (1969–1973). It uses SOHC architecture with mechanical fuel injection to deliver enhanced mid-range torque and improved high-RPM response. Designed before emissions mandates, it prioritizes mechanical purity and driver engagement over emissions control.
| Parameter | Value | Source |
|---|---|---|
Displacement | 2,341 cc | |
Fuel type | Petrol (RON 98 min) | |
Configuration | Flat‑6, SOHC, 12‑valve | |
Aspiration | Naturally aspirated | |
Bore × stroke | 84.0 mm × 70.4 mm | |
Power output | 125 kW (170 PS) @ 6,300 rpm | |
Torque | 206 Nm @ 5,000 rpm | |
Fuel system | Mechanical injection (Bosch PI system) | |
Emissions standard | None (pre-regulation era) | |
Compression ratio | 9.8:1 | |
Cooling system | Air‑cooled (fan‑driven) | |
Turbocharger | None | |
Timing system | Chain-driven SOHC (dual chains) | |
Oil type | SAE 20W‑50 mineral (Porsche spec. PS‑1969) | |
Dry weight | 165 kg |
The Porsche 911.47 was used exclusively in Porsche's 911 E and 911 S platforms with rear longitudinal mounting and no external licensing. This engine featured platform-specific adaptations—dry-sump oiling, high-flow heads, and reinforced valve springs—and from mid‑1970 received camshaft metallurgy upgrades, creating interchange limits. No partnerships existed for this engine. All adaptations are documented in OEM technical bulletins.
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Field reports and technical service bulletins highlight component wear patterns under high-load operation. Adherence to manufacturer service intervals and approved fluid specifications is critical for long-term reliability.
Analysis derived from Porsche technical bulletins (1969–1973) and Historic Porsche Club failure statistics (2000–2023). 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 911.47 is a refined evolution of the early flat-six and delivers excellent balance of performance and touring comfort, but pre-mid-1970 units suffer from cam lobe wear. Later revisions addressed this. With correct oil (20W‑50 mineral), frequent changes, and moderate use, it can be very reliable. Historic Porsche specialists consider it one of the most desirable pre-impact-bumper engines when properly maintained.
Top issues include cam lobe wear (especially on early 1969–1970 builds), mechanical fuel injection drift, oil sludge in the dry-sump system, and cooling fan belt failure. These are documented in Porsche Technical Bulletins PTB‑69‑04 and SIB 03 07 69. Regular mechanical inspection is essential.
The 911.47 was used in the 1969–1973 Porsche 911 E and 911 S models. It was never installed in base 911, Targa, 914, or competition variants. No other manufacturers used this engine; it was exclusive to Porsche’s high-compression 911 variants of the early 1970s.
Aftermarket ECU tuning is common on the 911-47 platform, but increasing boost or altering engine parameters accelerates component wear, impacts emissions compliance, and may void vehicle warranties. Any modifications should be evaluated carefully by a qualified specialist.
Approximately 14.0 L/100km (city) and 10.2 L/100km (highway), or about 20–21 mpg UK combined. Real-world usage in classic 911 E/S models typically yields 19–23 mpg UK depending on driving style. Requires RON 98 premium petrol for optimal performance and knock prevention.
Yes. The 911.47 is an interference design. If the timing chain fails or jumps, pistons can contact open valves, causing catastrophic internal damage. However, chain issues are rare; cam wear is the greater concern. Proper maintenance minimizes this risk significantly.
Porsche specified SAE 20W‑50 mineral oil meeting PS‑1969. Modern classic-specific oils (e.g., Millers Oils CFS 20W‑50) are acceptable. Avoid synthetics unless engine is rebuilt for them. Change every 5,000 km to protect cam lobes and maintain oil pressure.
Comprehensive technical documentation and regulatory references
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Regulatory Stability
EU regulations are referenced using CELEX identifiers for long-term stability.
EUR-Lex
EU emissions and type-approval regulations (e.g., CELEX:32007R0715, CELEX:32017R1151).
GOV.UK: Vehicle Approval & V5C
UK vehicle approval processes, import rules, and MoT guidance.
DVLA: Engine Changes & MoT
Official guidance on engine swaps and inspection implications.
Vehicle Certification Agency (VCA)
UK type-approval authority for automotive products.
Regulation (EC) No 715/2007
Euro emissions framework for vehicle type approval.
Commission Regulation (EU) 2017/1151
WLTP and RDE testing procedures for emissions certification.
GOV.UK: Vehicle Approval
UK compliance and certification requirements for imported and modified vehicles.
VCA Certification Portal
Type-approval guidance and documentation.
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