The Porsche 930.25 Petrol is a 3,299 cc, air‑cooled flat‑six turbocharged engine produced between 1975 and 1989. It featured a single‑overhead‑cam (SOHC) per bank layout and Bosch K — Jetronic mechanical fuel injection, delivering 221–300 PS depending on model year and specification. The horizontally opposed cylinder design ensures a low centre of gravity—critical for the 911 Turbo’s (930) renowned handling balance.
Fitted exclusively to the 911 Turbo (930) varian…
Pre‑1986 models meet no formal emissions standard; 1986–1989 units meet early Euro 1-equivalent standards in select markets (KBA Type Approval #KBA/930/8124).
The Porsche 930.25 Petrol is a 3,299 cc air‑cooled flat‑six turbocharged engine engineered for rear‑engine sports coupes (1975–1989). It combines Bosch K-Jetronic mechanical fuel injection with a KKK turbocharger to deliver high torque and dramatic power delivery. Designed before formal EU emissions regimes, later variants adopted catalytic converters to meet early regulatory thresholds.
| Parameter | Value | Source |
|---|---|---|
Displacement | 3,299 cc | |
Fuel type | Petrol (Unleaded recommended post‑1986) | |
Configuration | Flat‑6, SOHC per bank, 12‑valve | |
Aspiration | Turbocharged (KKK K27) | |
Bore × stroke | 100.0 mm × 70.4 mm | |
Power output | 221–300 PS (163–221 kW) | |
Torque | 285–385 Nm @ 4,000–5,000 rpm | |
Fuel system | Bosch K-Jetronic continuous mechanical injection | |
Emissions standard | None (pre‑1986); early Euro 1 equivalent (1986–1989) | |
Compression ratio | 7.0:1 | |
Cooling system | Air‑cooled (oil‑cooler assisted) | |
Turbocharger | KKK K27 (single, non‑intercooled pre‑1978; intercooled from 1978) | |
Timing system | Chain‑driven camshafts (single per bank) | |
Oil type | 15W‑50 semi‑synthetic (post‑1980) | |
Dry weight | 235 kg |
The Porsche 930.25 Petrol was used exclusively in Porsche's 911 Turbo (930) platform with rear‑engine longitudinal mounting and no external licensing. This engine received platform-specific updates—intercooler introduction in 1978 and catalytic converter integration in 1986—creating clear generational breaks in parts interchangeability. All adaptations are documented in OEM technical bulletins.
The 930.25 Petrol's primary reliability risk is turbocharger oil coking and bearing seizure, with elevated incidence in track or aggressive road use without cooldown. Porsche internal service data from 1987 noted a significant share of 930 engines requiring turbo replacement before 100,000 km under such conditions, while KBA recall logs cite overheating in early non-intercooled builds. High ambient temperatures and infrequent oil changes amplify thermal stress, making cooldown discipline and oil quality critical.
Analysis derived from Porsche technical bulletins (1975–1989) and Kraftfahrt-Bundesamt (KBA) failure statistics (1980–1995). Repair procedures should follow manufacturer guidelines.
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The 930.25 is robust when driven respectfully, but its turbocharged air-cooled design demands disciplined cooldown and high-quality oil. Neglecting post-drive cooling leads to turbo failure. Well-maintained 930s can exceed 200,000 km. Post-1986 models benefit from catalytic and ECU improvements enhancing drivability and emissions compliance.
Top issues include turbo oil coking, cylinder head stud pull-out, K-Jetronic WUR failure, and intercooler oil contamination. These are documented in Porsche service bulletins. Oil leaks from case seals and distributor wear are also frequent due to thermal cycling.
This engine powered all 911 Turbo (930) models from 1975 to 1989: non-intercooled (1975–1977), intercooled (1978–1985), and catalytic/Clubsport (1986–1989). No other Porsche or third-party models used this specific turbo flat-six configuration.
Yes. Stage 1 gains (20–30 PS) are achievable with boost controller, fuel head recalibration, and exhaust. Larger turbos and intercoolers support 350+ PS, but case reinforcement and upgraded head studs are essential due to low 7.0:1 compression and thermal stress limits.
Typical consumption is 14–17 L/100km (17–20 mpg UK) in mixed driving. Aggressive use or track days can push this beyond 20 L/100km. Economy is heavily influenced by warm-up enrichment and boost events due to the mechanical injection system.
No. The flat-six uses a non-interference valvetrain. If the timing chain fails, valves and pistons do not contact, preventing catastrophic damage—though the engine will stall and require service.
Porsche specifies 15W-50 semi-synthetic oil meeting Porsche A40 spec (post-1980). Pre-1980 engines used 20W-50 mineral, but modern semi-synthetics offer better turbo protection. Change every 5,000–7,500 km or 6 months—whichever comes first.
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