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) variants—including standard, SE, and later Clubsport models—the 930.25 was engineered for high‑performance road and occasional track use, emphasizing mid‑range torque and turbine‑driven thrust. Emissions compliance in European markets was achieved through thermal reactors and later catalytic converters, allowing adherence to early Euro 1-equivalent standards from 1986 onward.
One documented concern is turbocharger oil coking and bearing seizure, highlighted in Porsche Technical Bulletin PTB/83/14. This issue stems from insufficient post‑drive cooldown cycles in air‑cooled turbo engines, which trap heat in the center housing. In 1986, Porsche mandated a factory turbo timer function via ECU logic and revised oil feed lines to improve heat dissipation.
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 turbocharged flat-six delivers dramatic mid-range thrust but requires disciplined cooldown after spirited driving to prevent turbo bearing coking. Extended idling post-drive or immediate shutdown after boost use traps heat in the center housing, degrading oil and seizing bearings. Use of 15W-50 semi-synthetic oil is critical from 1980 onward. Cold starts below 0°C should be followed by 10+ minutes of gentle driving. The K-Jetronic system is sensitive to fuel pressure and altitude—only OEM-spec pumps and warm-up regulators ensure stable operation. Intercooled 1978+ models demand regular inspection of the air-to-air intercooler ducts for oil residue or leaks.
Oil Specs: Requires 15W-50 semi-synthetic oil per Porsche Tech Bulletin PTB/83/14. Mineral oils are not recommended post-1980 due to turbo thermal stress.
Emissions: No formal emissions standard applies to pre-1986 models. 1986–1989 units meet early Euro 1-equivalent thresholds in Germany (KBA Type Approval #KBA/930/8124).
Power Ratings: Measured under DIN 70020 standards. 300 PS Clubsport output requires 98 RON fuel and intercooler system integrity (Porsche TIS Doc. P930‑89A).
Porsche Technical Information System (TIS): Docs P930‑75A, P930‑75B, P930‑78D, P930‑89A
KBA Type Approval Database (KBA/930/8124)
DIN 70020 Engine Power Measurement Standard
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.
Engine code is stamped on the crankcase near the flywheel housing (Porsche TIS P930‑75A). The 7th–8th VIN digits are '930' for all Turbo models. Non-intercooled (1975–1977) cars feature a flat rear decklid; intercooled (1978+) have the iconic 'whale tail' spoiler with integrated air intake. Turbocharger housing is marked 'KKK K27'. Bosch K-Jetronic fuel distributor carries part number 0 438 100 xxx. Oil cooler size increased in 1980—pre-1980 units have 28-row cooler; post-1980 use 34-row.
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.
Find answers to most commonly asked questions about PORSCHE 930-25.
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