The Porsche 930.21 is a 2,994 cc, air‑cooled flat‑six turbocharged petrol engine produced between 1975 and 1989. It featured a K27 turbocharger, Bosch K — Jetronic mechanical fuel injection, and an air — to — air intercooler system. In road — going 911 Turbo (930) form, it delivered 221–257 kW (300–350 PS), with torque ranging from 380 to 450 Nm.
Fitted exclusively to the 911 Turbo (930) during its production run—including both narrow — body (1975–1977) and wide — body “whale…
Production years 1975–1986 meet no formal EU emissions standard; 1987–1989 models may meet Euro 1 depending on market (EU Regulation 88/77/EEC).
The Porsche 930.21 is a 2,994 cc flat‑six turbocharged petrol engine engineered for high‑performance 911 Turbo models (1975–1989). It combines Bosch K-Jetronic mechanical fuel injection with a single K27 turbocharger and air-to-air intercooler to deliver strong mid‑range thrust and iconic turbo lag. Designed without formal early EU emissions targets but retrofitted with catalysts in later years, it balances raw power with period‑appropriate drivability.
| Parameter | Value | Source |
|---|---|---|
Displacement | 2,994 cc | |
Fuel type | Petrol (Unleaded) | |
Configuration | Flat‑6, SOHC, 12‑valve | |
Aspiration | Turbocharged (single K27) | |
Bore × stroke | 95.0 mm × 70.4 mm | |
Power output | 221–257 kW (300–350 PS) | |
Torque | 380–450 Nm @ 4,000–4,500 rpm | |
Fuel system | Bosch K-Jetronic (continuous mechanical injection) | |
Emissions standard | None (pre‑1987); Euro 1 (1987–1989, select markets) | |
Compression ratio | 6.5:1 (turbocharged) | |
Cooling system | Air‑cooled | |
Turbocharger | Kühnle, Kopp & Kausch K27 (air-to-air intercooled) | |
Timing system | Chain-driven SOHC | |
Oil type | Porsche Classic 20W‑50 or equivalent mineral | |
Dry weight | 180 kg |
The Porsche 930.21 was used exclusively in Porsche's 911 Turbo (930) platform with rear-engine, longitudinal mounting and no external licensing. This engine received platform-specific adaptations—narrow-body air intakes (1975–1977) and wide-body intercooler ducting (1978 onward)—and from 1987 the facelifted 930/88 models adopted reinforced rod bearings and upgraded oil coolers, creating minor service part interchange limits. All adaptations are documented in OEM technical bulletins.
The 930.21's primary reliability risk is turbocharger and bearing failure due to oil coking under high heat, with elevated incidence in track or hot‑climate use. Porsche internal service data from 1988 indicated over 30 % of high‑mileage units required turbo or main bearing replacement before 100,000 km, while owner surveys correlate neglected oil changes with catastrophic engine seizure. Extended idling and aggressive driving without cooldown cycles accelerate wear, making oil quality and thermal management critical.
Analysis derived from Porsche technical bulletins (1975–1989) and EU vehicle failure statistics (1985–2023). 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 930.21 offers thrilling performance but demands meticulous maintenance. Early models (1975–1986) lack emissions controls but suffer from turbo heat issues. Later versions (1987–1989) added reliability upgrades. Using correct mineral oil and adhering to 5,000 km oil changes is essential for longevity—well-cared-for examples can exceed 150,000 km.
Top issues include turbo oil coking, K-Jetronic fuel system drift, rear main seal leaks, and intercooler duct failures. Heat management is critical—many failures stem from oil degradation or thermal stress. Porsche service bulletins (e.g., 930/01/78) document these concerns extensively.
Exclusively the 911 Turbo (930) from 1975–1989—first as the 3.0L (1975–1977), then the 3.3L (1978–1989). No other Porsche or external brands used this engine. All are rear-engine, rear-wheel-drive coupés with the iconic “whale tail” spoiler.
Yes—common upgrades include larger K27 variants, improved intercoolers, and K-Jetronic recalibration. Stage 1 typically yields 380–400 PS. However, the air-cooled block and original rods limit safe output; going beyond 450 PS risks bearing failure without internal reinforcement.
Modest for a performance car: ~14.5 L/100km (city) and ~10.2 L/100km (highway), or ~19 mpg UK combined. Aggressive driving can push consumption beyond 20 L/100km. The K-Jetronic system is inefficient by modern standards but offers robust mechanical reliability when maintained.
No. The 930.21 uses a non-interference valvetrain design—pistons and valves do not occupy the same space if timing fails. However, catastrophic turbo or bearing failure can still cause internal engine damage due to oil starvation or foreign debris.
Porsche specifies a high-zinc 20W‑50 mineral oil (e.g., Porsche Classic). Synthetic oils are not recommended for original flat-tappet camshafts. Change oil every 5,000 km or 6 months—whichever comes first—to prevent turbo coking and bearing wear.
Comprehensive technical documentation and regulatory references
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