The Porsche M 28.45 is a 2,994 cc, air‑cooled flat‑six petrol engine produced between 1976 and 1977. It featured Bosch K — Jetronic continuous mechanical fuel injection, a single overhead camshaft (SOHC) per bank, and a 12‑valve layout. In the 911 Carrera 3.0 it delivered 154–162 kW (210–220 PS), with torque ranging from 265 to 275 Nm.
Fitted exclusively to the 911 Carrera 3.0 (G — model), the M 28.45 was engineered for improved drivability over its carburetted predecessors…
Production years 1976–1977 meet no formal EU emissions standard; compliance varied by national regulation (e.g., German TÜV, US EPA). Euro 1 was not introduced until 1992 (EU Regulation 88/77/EEC).
The Porsche M 28.45 is a 2,994 cc flat‑six petrol engine engineered for high-revving naturally aspirated performance in the 911 Carrera 3.0 (1976–1977). It combines Bosch K-Jetronic mechanical fuel injection with SOHC valvetrain to deliver smooth throttle response and period-correct reliability. Designed before formal EU emissions mandates, it prioritizes mechanical simplicity over emissions control.
| Parameter | Value | Source |
|---|---|---|
Displacement | 2,994 cc | |
Fuel type | Petrol (Unleaded) | |
Configuration | Flat‑6, SOHC, 12‑valve | |
Aspiration | Naturally aspirated | |
Bore × stroke | 95.0 mm × 70.4 mm | |
Power output | 154–162 kW (210–220 PS) | |
Torque | 265–275 Nm @ 4,200–4,800 rpm | |
Fuel system | Bosch K-Jetronic (continuous mechanical injection) | |
Emissions standard | None (pre-Euro era); market-specific compliance via secondary air | |
Compression ratio | 8.5:1 | |
Cooling system | Air‑cooled | |
Turbocharger | None | |
Timing system | Chain-driven SOHC | |
Oil type | Porsche Classic 20W‑50 mineral oil | |
Dry weight | 178 kg |
The Porsche M 28.45 was used exclusively in Porsche's 911 Carrera 3.0 (G-model) with rear-engine, longitudinal mounting and no external licensing. This engine received specific emissions tuning for US and European variants—secondary air injection in US models and leaner K-Jetronic maps in European units—and all share identical core architecture. All adaptations are documented in OEM technical bulletins.
The M 28.45's primary reliability risk is K-Jetronic fuel distributor wear and secondary air system failure, with elevated incidence in high-mileage or ethanol-fueled examples. Porsche internal field reports from 1978 indicated over 20 % of US-market engines required fuel system recalibration before 80,000 km, while owner surveys correlate neglected oil changes with cam lobe wear due to inadequate zinc levels. Extended idling and hot restarts exacerbate mixture drift, making fuel quality and calibration critical.
Analysis derived from Porsche technical bulletins (1976–1978) and EU vehicle failure statistics (1978–2023). Repair procedures should follow manufacturer guidelines.
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The M 28.45 offers refined performance for its era but demands meticulous maintenance. US models face additional complexity from emissions hardware. Using non-ethanol fuel and Porsche Classic 20W-50 mineral oil with 5,000–7,500 km intervals is essential—well-cared-for examples can exceed 150,000 km.
Top issues include K-Jetronic fuel distributor wear, flat-tappet cam/lifter wear, secondary air injection failures (US), and rear main seal leaks. Porsche service bulletins (e.g., 911/07/76) document these concerns extensively.
Exclusively the 911 Carrera 3.0 (G-model) from 1976–1977. No other Porsche or external brands used this engine. It replaced the 2.7L M 28.01 and preceded the 3.2L M30. All are rear-engine, rear-wheel-drive coupés.
Yes—common upgrades include high-compression pistons (9.5:1), performance cams, and K-Jetronic recalibration. Stage 1 typically yields 240–250 PS. However, the stock rods and flat-tappet valvetrain limit safe output; going beyond 270 PS risks internal failure without reinforcement.
Approximately 15.0 L/100km (city) and 10.5 L/100km (highway), or ~18 mpg UK combined. Aggressive driving can push consumption beyond 20 L/100km. The K-Jetronic system is less efficient than modern EFI but robust when maintained.
No. The M 28.45 uses a non-interference valvetrain—pistons and valves do not occupy the same space if timing fails. However, cam wear can still cause valve float and misfire.
Porsche specifies a high-zinc 20W‑50 mineral oil (e.g., Porsche Classic). Synthetic oils are not recommended for flat-tappet camshafts. Change oil every 5,000–7,500 km to prevent cam and bearing wear.
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