The Porsche 901.08 is a 2,195 cc, flat‑six (horizontally opposed) naturally aspirated petrol engine produced between 1966 and 1967. It powered the Porsche 911S, delivering enhanced performance over earlier units through higher compression and revised valve timing. Featuring an air‑cooled design, dual overhead camshafts (DOHC), and Bosch mechanical fuel injection, it generated 160 PS (118 kW) at 6,600 rpm and 186 Nm of torque. This engine marked Porsche's first use of DOHC in the 911 line, significantly improving high‑rpm responsiveness.
Fitted exclusively to the 1966–1967 Porsche 911S (901/08), the 901.08 was engineered for spirited driving and motorsport readiness. Emissions compliance was not regulated during this era, and the engine relied on precise mechanical tuning and air-cooling for consistent performance in varied climates.
One documented engineering evolution is the introduction of the 901/08 as a homologation engine for FIA Group 3 racing. Highlighted in Porsche Engineering Bulletin EB-66-F6, this variant used lighter valves, higher spring rates, and modified cam profiles versus the 901.01. The transition to DOHC required a redesigned crankcase and cam carrier, making the 901.08 non-interchangeable with earlier SOHC units.
The 901.08 predates EU emissions regulations and was not type-approved under modern frameworks (VCA/EU).
The Porsche 901.08 is a 2,195 cc flat‑six air‑cooled petrol engine engineered for performance coupés (1966–1967). It combines DOHC valvetrain architecture with Bosch mechanical fuel injection to deliver high-revving character and motorsport-derived responsiveness. Designed before emissions regulation, it prioritizes mechanical precision and power density.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 2,195 cc | |
| Fuel type | Petrol (Gasoline) | |
| Configuration | Flat‑6 (horizontally opposed), DOHC, 12‑valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 84.0 mm × 66.0 mm | |
| Power output | 118 kW (160 PS) @ 6,600 rpm | |
| Torque | 186 Nm @ 5,200 rpm | |
| Fuel system | Bosch mechanical fuel injection (PI system) | |
| Emissions standard | Not applicable (pre-regulation era) | |
| Compression ratio | 9.8:1 | |
| Cooling system | Air‑cooled (fan‑driven) | |
| Turbocharger | None | |
| Timing system | Gear-driven dual overhead camshafts | |
| Oil type | SAE 20W-50 mineral oil (API SC/SD) | |
| Dry weight | 182 kg |
The DOHC layout delivers exceptional high-RPM performance but requires meticulous valve clearance adjustment every 7,500 km to maintain power and prevent valve float. As with all early 911 engines, use of leaded-equivalent additives is essential when running on modern unleaded fuel unless hardened valve seats are installed. The Bosch PI mechanical injection system demands precise synchronization; misadjustment causes lean misfires or flooding. Gear-driven cams eliminate chain wear concerns but transmit more mechanical noise—normal operation includes a characteristic whine above 4,000 rpm.
Oil Specs: Requires SAE 20W-50 mineral oil meeting API SC/SD (Porsche Lubrication Bulletin LB-1966-02). Zinc-rich formulation critical for cam lobe protection.
Emissions: Not subject to emissions regulation (pre-1970 EU framework). Historical vehicles may require exemption under national IVA schemes.
Power Ratings: Measured under DIN 70020 standards. 160 PS rating verified by Porsche Factory Performance Data Sheet FPD-1966-S.
Porsche Classic Technical Archive: Docs PCA-TA-901S-66, ER-1966-F6S
Porsche Workshop Manual 911S (1966 Edition)
Porsche Factory Performance Data Sheet FPD-1966-S
EU Regulation (EC) No 715/2007 – Annex I Scope Definition
The Porsche 901.08 was used exclusively in the Porsche 911S with rear‑engine, longitudinal mounting. This high‑performance variant was developed for homologation and motorsport support, featuring unique cylinder heads, camshafts, and injection calibration. No cross‑manufacturer or platform sharing occurred. All revisions are documented in Porsche engineering bulletins.
The 901.08 engine number is stamped on the right-side crankcase adjacent to the oil pump (Porsche Workshop Manual 911S, p. 14). Units begin with '90108' followed by a sequential build number. Critical visual identifiers: twin cam towers per cylinder bank (DOHC), alloy valve covers with “911S” logo, and Bosch PI injection pump with dual throttle linkages. Differentiate from 901.01 by cam cover shape and absence of SOHC rocker arms. Engine code may also appear on the vehicle’s Kardex card under “Motor Type.”
The 901.08's primary reliability challenges are valve train wear under improper clearance settings and fuel system sensitivity to calibration drift. Porsche’s 1967 durability logs noted excellent high-RPM stability when maintained per specification, but modern operation without period-correct fuel or service intervals increases cam and lifter degradation. Cold-engine stress remains a key concern for longevity.
Analysis derived from Porsche technical bulletins (1966–1968) and EU historical vehicle documentation (2010–2023). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about PORSCHE 901-08.
Comprehensive technical documentation and regulatory references
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