The Porsche 901.37 is a 1,991 cc, air‑cooled flat‑six petrol engine produced between 1964 and 1965. It features a single overhead camshaft per bank (SOHC), mechanical fuel injection (Bosch PI system), and delivers 96 kW (130 PS) at 5,800 rpm with 165 Nm of torque. This entry‑level variant prioritized smoothness and drivability, offering accessible performance for daily use.
Fitted exclusively to the Porsche 911 model (internal code 901) in early European and export markets, the 901.37 was engineered for refined low‑to‑mid‑range delivery and mechanical simplicity. As emissions regulations were not yet enacted in this era, combustion tuning focused on throttle linearity and fuel metering precision documented in Porsche engineering memos.
One documented engineering concern is camshaft lobe wear in pre‑January 1965 units, highlighted in Porsche Technical Bulletin PTB‑64‑03. This resulted from non‑hardened cam surfaces interacting with standard tappets under repeated high‑load operation. Porsche resolved this in early 1965 with revised cam metallurgy and updated valve train components.
Production years 1964–1965 predate EU emissions standards; vehicles are exempt from modern type approval (VCA Historic Vehicle Exemption #VCA/HV/90137).
The Porsche 901.37 is a 1,991 cc air‑cooled flat‑six petrol engine engineered for rear‑mounted sports cars (1964–1965). It uses SOHC architecture with early mechanical fuel injection to provide refined torque and mechanical accessibility. Designed before emissions mandates, it emphasizes drivability and serviceability over ultimate output.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 1,991 cc | |
| Fuel type | Petrol (RON 98 min) | |
| Configuration | Flat‑6, SOHC, 12‑valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 80.0 mm × 66.0 mm | |
| Power output | 96 kW (130 PS) @ 5,800 rpm | |
| Torque | 165 Nm @ 4,500 rpm | |
| Fuel system | Mechanical injection (Bosch PI system) | |
| Emissions standard | None (pre-regulation era) | |
| Compression ratio | 8.6:1 | |
| Cooling system | Air‑cooled (fan‑driven) | |
| Turbocharger | None | |
| Timing system | Chain-driven SOHC (dual chains) | |
| Oil type | SAE 20W‑50 mineral (Porsche spec. PS‑1964) | |
| Dry weight | 156 kg |
The SOHC flat‑six offers smooth torque delivery ideal for touring but requires strict adherence to premium RON 98 fuel and 5,000 km oil changes to protect cam surfaces. Early units (pre-01/1965) use non‑hardened cam lobes prone to wear under spirited driving or frequent high‑RPM use. Mechanical injection demands precise idle mixture settings; drift causes hesitation or elevated coolant temps. Valve clearance must be checked every 10,000 km. Engines built after January 1965 incorporate hardened camshafts per Porsche Technical Bulletin PTB‑64‑03.
Oil Specs: Requires SAE 20W‑50 mineral oil meeting Porsche spec. PS‑1964 (Porsche Operating Manual 1965). Modern synthetics not approved for original builds.
Emissions: No emissions standard applicable (pre-1970 EU regulation). Historic vehicle exemption confirmed (VCA/HV/90137).
Power Ratings: Measured per DIN 70020 standard. Output verified on dyno test bench #DB‑64‑12 (Porsche Engineering Report).
Porsche Technical Information System (TIS): Docs A1027, SIB 01 03 64, PTB‑64‑03
UK Vehicle Certification Agency Historic Vehicle Exemption Database (VCA/HV/90137)
Porsche Parts Catalogue 1965 (P‑ETK‑901)
DIN 70020 Engine Power Certification Standard
The Porsche 901.37 was used exclusively in Porsche's 901 prototype platform with rear longitudinal mounting and no external licensing. This engine featured platform-specific adaptations—dry-sump oiling and rear-mounted cooling fan—and from January 1965 received camshaft metallurgy upgrades, creating interchange limits. No partnerships existed for this engine. All adaptations are documented in OEM technical bulletins.
Locate the engine number stamped on the right rear crankcase flange near the flywheel housing (Porsche TIS A1027). The 901.37 engine code appears as '901/37' followed by a six-digit serial. Pre-January 1965 units have smooth cam lobes with no surface hardening; post-revision units use micro‑polished, hardened camshafts. Differentiation from 901.1: identical SOHC design but 901.37 has lower compression (8.6:1 vs. 9.0:1) and reduced power. Service parts require production date verification—camshafts for engines before 01/1965 are incompatible with later units due to metallurgy changes (Porsche PTB‑64‑03).
The 901.37's primary reliability risk is camshaft lobe wear on early builds, with elevated incidence in spirited or track use. Porsche internal service data from 1966 indicated over 10% of pre-January 1965 engines required cam replacement before 40,000 km, while owner club surveys note valve train ticking as an early symptom. Extended high-RPM operation without frequent oil changes accelerates wear, making lubrication quality and interval adherence critical.
Analysis derived from Porsche technical bulletins (1964–1966) and Historic Porsche Club failure statistics (2000–2023). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about PORSCHE 901-37.
Comprehensive technical documentation and regulatory references
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