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 tail” (1978–1989) variants—the 930.21 was engineered for high‑performance grand touring with unmistakable turbo lag characteristic of early forced induction. Emissions compliance was achieved via lean‑mix K-Jetronic tuning and exhaust catalysts on later models, meeting Euro 1 standards in select markets by 1989 (EU Regulation 88/77/EEC).
One documented concern is heat‑related oil degradation due to the air‑cooled architecture under sustained high load, which can accelerate main bearing wear and turbo failure. This issue is referenced in Porsche Technical Bulletin 930/01/78, which recommends enhanced cooling maintenance and oil change intervals for track or hot‑climate use. In 1987, Porsche introduced reinforced rod bearings and improved oil coolers for high‑output variants.
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 K27 turbo delivers dramatic mid-range surge but with noticeable lag below 3,000 rpm, requiring anticipatory driving. Air-cooling demands vigilant oil monitoring—oil changes every 5,000 km or 6 months are critical to prevent main bearing wear and turbo coking. Use only high-zinc mineral oil (e.g., Porsche Classic 20W-50) to protect flat-tappet cam followers. The K-Jetronic system is sensitive to fuel pressure and requires precise metering adjustment; ethanol-blended fuels can degrade rubber components in the fuel distributor. Turbo and intercooler ducts must remain sealed to prevent lean spikes and detonation.
Oil Specs: Requires high-zinc mineral oil (e.g., Porsche Classic 20W-50) per Porsche SIB 930/01/78. Synthetic oils not recommended for original flat-tappet valvetrain.
Emissions: No formal standard before 1987. Euro 1 compliance introduced in 1987–1989 for certain EU markets (EU Regulation 88/77/EEC).
Power Ratings: Measured under DIN 70020. 257 kW (350 PS) output achieved in 1989 G-model with updated K27 turbo and intercooler (Porsche PT‑1989).
Porsche Technical Information System (TIS): Docs P930‑A24, P930‑A31, SIB 930/01/78
EU Regulation 88/77/EEC on vehicle emissions
Porsche Parts Catalogue (ETK) 1989 Edition
SAE International: DIN 70020 Power Measurement Standard
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.
Locate the engine type plate riveted to the crankcase near the oil filler tube—it reads “930/xx” (e.g., 930/70 for early 3.0L, 930/60 for 3.3L). The 7th VIN digit is always “9” for 930 Turbo. Early engines (1975–1977) have a smaller intercooler scoop and lack catalytic converter; 1987–1989 models include cat and revised oil cooler. Turbocharger part number (K27/xx) is stamped on the compressor housing. Do not confuse with naturally aspirated 911SC (type 930/03)—the 930.21 always has rear spoiler and turbo ducting.
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.
Find answers to most commonly asked questions about PORSCHE 930-21.
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