The Porsche 901.09 is a 1,991 cc, flat‑six (horizontally opposed) naturally aspirated petrol engine produced between 1967 and 1969. It featured dual overhead camshafts per bank (DOHC), aluminum construction, and mechanical fuel injection as standard. In road trim it delivered 160 PS (118 kW) at 6,600 rpm with 177 Nm of torque, offering a high-revving performance character and motorsport-derived responsiveness.
Fitted exclusively to the 911S (1967–1969), the 901.09 was engineered for spirited driving and track capability, emphasizing throttle response and top-end power over low-end torque. Emissions control was minimal by modern standards; the engine predates EU emissions frameworks but complied with contemporary German KBA type approval standards.
One documented concern is valve train wear under sustained high-RPM use, particularly in pre‑late‑1968 builds. This issue, highlighted in Porsche Technical Bulletin PTB 68/09, stems from early rocker arm pivot geometry and oil feed limitations. From late 1968, Porsche revised oil galleries and introduced nitrided camshafts to enhance durability.
Production years 1967–1969 predate Euro standards; all units comply with German KBA type approval requirements of the era (KBA Type Approval #A-2845/67).
The Porsche 901.09 is a 1,991 cc flat‑six petrol engine engineered for high-performance sports cars (1967–1969). It combines DOHC architecture with Bosch mechanical fuel injection to deliver a high-revving, responsive driving experience. Designed before formal EU emissions standards, it met contemporary German KBA requirements for safety and drivability.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 1,991 cc | |
| Fuel type | Petrol (RON 98 min.) | |
| Configuration | Flat‑6, DOHC, 12‑valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 80.0 mm × 66.0 mm | |
| Power output | 160 PS (118 kW) @ 6,600 rpm | |
| Torque | 177 Nm @ 5,200 rpm | |
| Fuel system | Bosch mechanical fuel injection (Kugelfischer PL 3/4) | |
| Emissions standard | Pre-Euro; KBA-compliant (1967–1969) | |
| Compression ratio | 9.8:1 | |
| Cooling system | Air‑cooled | |
| Turbocharger | None | |
| Timing system | Chain-driven DOHC (front-mounted) | |
| Oil type | SAE 20W-50 mineral (API SF/CC spec) | |
| Dry weight | 175 kg |
The air‑cooled flat‑six with mechanical injection delivers precise throttle response but demands strict adherence to oil change intervals (every 5,000–7,500 km) using high-zinc mineral oil to protect cam lobes and lifters. Valve clearances must be checked every 10,000 km due to mechanical tappets. Late‑1968+ units benefit from improved oiling; pre‑late‑1968 engines should consider camshaft upgrades per Porsche SIB 68/09. Ethanol‑free, high-octane (RON 98+) fuel is essential to prevent detonation and preserve injection pump calibration.
Oil Specs: Requires high-zinc SAE 20W-50 mineral oil (API SF/CC). Modern synthetics may lack ZDDP levels needed for flat-tappet protection.
Emissions: Pre-Euro engine; complies with 1967–1969 German KBA type approval (KBA #A-2845/67). No EU emissions certification applies.
Power Ratings: Measured under DIN 70020 standards. Output assumes RON 98 fuel and properly calibrated Kugelfischer injection (Porsche PT-1968).
Porsche Technical Information System (TIS): Docs 901-1109, SIB 68/03, SIB 68/09
Kraftfahrt-Bundesamt (KBA) Type Approval Database (A-2845/67)
DIN 70020 Engine Power Certification Standard
Porsche Engineering Report ER-67-11
The Porsche 901.09 was used exclusively in Porsche's 911S platform with rear‑mounted, longitudinal orientation and no external licensing. This engine received minor running updates—revised oil pump in late 1968 and nitrided camshafts from early 1969—and remained distinct from the base 901/02 and rally-spec 901/20 variants, creating strict interchange limits. All adaptations are documented in OEM technical bulletins.
Locate the engine type stamped on the left crankcase near the oil filler neck (Porsche TIS 901-1109). The 901.09 appears as “901/09” or “Type 901/09”. All units feature black-painted cam covers and mechanical injection with a distinctive Kugelfischer pump mounted on the right side. Critical differentiation from 901/02: 901.09 always has mechanical injection and higher-compression pistons. Late-1968+ engines include an additional oil feed to the cam chain tensioner; verify production date before ordering timing components (Porsche SIB 68/09).
The 901.09's primary reliability risk is valve train wear in pre-late-1968 builds, with elevated incidence in track or aggressive street use. Porsche internal service data from 1969 noted cam/rocker issues in ~12% of early 901.09 engines before 50,000 km, while KBA field reports linked high-revving operation to oil starvation under marginal conditions. Infrequent oil changes and low-octane fuel exacerbate wear, making correct oil specification and valve adjustments critical.
Analysis derived from Porsche technical bulletins (1967-1969) and German KBA failure statistics (1968-1973). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about PORSCHE 901-09.
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