The Porsche M28.09 is a 2,142 cc, inline‑four petrol engine produced between 1978 and 1986. It powered the front — engine Porsche 924 and was notable for its water — cooled architecture in a brand dominated by air — cooled flat — sixes. Featuring a single overhead camshaft (SOHC), Bosch L — Jetronic electronic fuel injection, and an aluminum block with cast — iron liners, it delivered 95 kW (130 PS) and 182 Nm of torque.
Fitted exclusively to the 924 (G — series) across global mark…
Production years 1978–1986 meet national emissions standards of the era; Euro 1-equivalent compliance applies to select export models (VCA UK Type Approval #VCA/EMS/924E).
The Porsche M28.09 is a 2,142 cc inline‑four petrol engine engineered for front-engine sports coupes (1978–1986). It combines Bosch L-Jetronic electronic fuel injection with an aluminum block and SOHC valvetrain to deliver smooth, reliable power with modest performance. Designed before formal EU emissions standards, later units incorporated modifications to meet national and VCA-equivalent requirements.
| Parameter | Value | Source |
|---|---|---|
Displacement | 2,142 cc | |
Fuel type | Petrol (RON 95 min) | |
Configuration | Inline‑4, SOHC, 8‑valve | |
Aspiration | Naturally aspirated | |
Bore × stroke | 97.0 mm × 72.6 mm | |
Power output | 95 kW (130 PS) @ 5,500 rpm | |
Torque | 182 Nm @ 3,500 rpm | |
Fuel system | Bosch L-Jetronic electronic injection | |
Emissions standard | Pre-Euro; national equivalents (e.g., VCA) | |
Compression ratio | 9.3:1 | |
Cooling system | Water-cooled | |
Turbocharger | None | |
Timing system | Chain-driven SOHC | |
Oil type | SAE 10W-40 mineral oil (API SF/CC) | |
Dry weight | 134 kg |
The Porsche M28.09 was used exclusively in Porsche's 924 platform with front-mounted, longitudinal orientation and no external licensing. This engine received minor updates—revised head gaskets from 1983 and updated ECU calibrations for catalytic models—and all adaptations are documented in OEM technical bulletins.
The M28.09's primary reliability risk is head gasket failure in pre-1983 units, with elevated incidence in high-ambient climates or neglected cooling systems. Porsche internal data from 1984 indicated head gasket repairs in over 15% of early 924s by 100,000 km, while UK DVSA records show associated overheating complaints in poorly maintained examples. Coolant integrity and thermal management make preventative maintenance critical.
Analysis derived from Porsche technical bulletins (1978–1986) and UK DVSA failure statistics (1987–2023). Repair procedures should follow manufacturer guidelines.
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The M28.09 can be dependable if maintained properly, but early models (1978–1982) are prone to head gasket failure. Post-1983 units with the MLS gasket are significantly more robust. Critical factors include using correct coolant, adhering to oil change intervals, and avoiding overheating. Neglect often leads to gasket or cooling system issues.
Top issues include head gasket blowouts (pre-1983), timing chain tensioner wear, L-Jetronic sensor faults, and water pump leaks. These are well-documented in Porsche service bulletins TSB-924-1983 and related TIS updates. Cooling system neglect is the primary accelerant.
Exclusively the Porsche 924 from 1978 to 1986, including standard and Carrera GT homologation variants. Early 924S models (pre-1987) also used the M28.09 before switching to the 2.5L M44/40. It was never used in 944, 911, or other Porsche lines.
Modestly. Stage 1 (performance chip, exhaust, intake) yields ~140–145 PS. Full builds with higher-compression pistons and cam upgrades can reach 160 PS. However, stock internals tolerate only limited increases—excessive tuning risks head gasket integrity and cooling capacity.
Typical consumption is 9–11 L/100km (26–21 mpg UK) in mixed driving. Highway cruising can reach 7.5 L/100km (38 mpg UK). The engine prioritizes smoothness and reliability over peak efficiency, though it remains frugal by sports car standards of its era.
No. The M28.09 is a non-interference engine. If the timing chain fails, valves and pistons do not collide, reducing risk of catastrophic damage. However, chain tensioner inspection is still recommended during major services.
Porsche specifies SAE 10W-40 mineral oil meeting API SF/CC standards. Synthetic oils were not approved for this engine family. Change every 7,500 km or annually to protect hydraulic lifters and chain system.
Comprehensive technical documentation and regulatory references
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