The Porsche M 28.42 is a 2,661 cc, water-cooled V6 petrol engine produced between 1983 and 1986. It features a 60° V-angle, single overhead camshafts (SOHC), and Bosch K-Jetronic mechanical fuel injection. In standard 924 S and 944 form it delivered 118–125 kW (160–170 PS) and 235–240 Nm of torque, with linear power delivery ideal for balanced handling and daily usability.
Fitted to the Porsche 924 S (1986) and 944 (1983–1986)—both front-engine, transaxle layouts—the M 28.42 was derived from the Audi/Volkswagen EA837 V6 but extensively re-engineered by Porsche for rear transaxle integration and performance refinement. Emissions compliance relied on thermal reactors and later catalytic converters, meeting Euro 0 standards with select export models achieving limited Euro 1 alignment.
One documented concern is premature wear of the balance shaft chain, identified in Porsche Technical Bulletin 944/601/84. This stems from marginal lubrication in the chain tensioner during extended low-RPM operation. In 1987, Porsche upgraded the engine to the M 44.01 with revised balance shafts and electronic fuel injection.
Production years 1983–1985 meet Euro 0 standards; 1986 US-spec 924 S models may have limited Euro 1 compliance depending on configuration (VCA UK Type Approval #VCA/EMS/6789).
The Porsche M 28.42 is a 2,661 cc water-cooled V6 petrol engine engineered for the 924 S and 944 (1983–1986). It combines SOHC architecture with Bosch K-Jetronic mechanical fuel injection to deliver smooth torque and refined drivability. Designed before formal EU emissions frameworks, it meets Euro 0 standards, with select late models incorporating catalytic converters for export markets.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 2,661 cc | |
| Fuel type | Petrol (RON 95 min) | |
| Configuration | V6, SOHC, 12-valve (60° V-angle) | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 89.0 mm × 72.0 mm | |
| Power output | 118–125 kW (160–170 PS) @ 5,800–6,000 rpm | |
| Torque | 235–240 Nm @ 3,500–4,200 rpm | |
| Fuel system | Bosch K-Jetronic mechanical injection | |
| Emissions standard | Euro 0 (pre-1986); limited Euro 1 for US-spec 1986 | |
| Compression ratio | 9.7:1 | |
| Cooling system | Water-cooled | |
| Turbocharger | None | |
| Timing system | Dual chains: primary cam chain + secondary balance shaft chain | |
| Oil type | Porsche-approved 10W-40 mineral or semi-synthetic | |
| Dry weight | 168 kg |
The M 28.42 delivers smooth, linear power well-suited to the 944’s handling balance but requires attention to the balance shaft chain system. Extended idling or frequent short trips accelerate chain tensioner wear, potentially leading to chain slap or failure. Use of RON 95 fuel is sufficient, though RON 98 improves combustion smoothness. Oil changes every 7,500 km with quality 10W-40 oil preserve chain and cam longevity. Bosch K-Jetronic demands clean fuel filters and intact control pressure regulators to avoid lean running. Balance shaft chain upgrades per Porsche SIB 944/601/84 are recommended during rebuilds.
Oil Specs: Requires mineral or semi-synthetic 10W-40 meeting Porsche 1980s specs (Porsche Lubricants Guide Rev.1). Full synthetics may affect K-Jetronic warm-up behavior.
Emissions: Euro 0 certification applies to all non-US models (VCA Type Approval #VCA/EMS/6789). 1986 US 924 S models used catalytic converters and basic OBD for CARB compliance.
Power Ratings: Measured under DIN 70020 standards. 125 kW output requires intact vacuum retard system and proper fuel pressure (Porsche TIS Doc. 944-02-84).
Porsche Technical Information System (TIS): Docs 944-01-83, 944-02-84, SIB 944/601/84
VCA Type Approval Database (VCA/EMS/6789)
SAE International: J1349 Engine Power Certification Standards
The Porsche M 28.42 was used exclusively in Porsche's 944 and 924 S platforms with front-engine, longitudinal mounting and no external licensing. This engine received Porsche-specific adaptations—revised oil pan for transaxle clearance, relocated accessories, and strengthened mounts—and from 1987 the 944 adopted the M 44.01 with updated injection and balance shafts, creating a hard interchange limit. All adaptations are documented in OEM technical bulletins.
Locate the engine type stamped on the front timing cover near the balance shaft housing (Porsche TIS 944-01-83). The engine code "M 28.42" appears on a foil label attached to the intake manifold. Early (1983–1985) 944 units use a single-row balance shaft chain; the 1986 924 S and late 944 may have minor tensioner revisions. Critical differentiation from Audi EA837: Porsche version has unique bellhousing pattern, relocated alternator, and oil pump drive gear. Balance shaft chain wear is internal—requires inspection after 120,000 km per Porsche SIB 944/601/84.
The M 28.42's primary reliability risk is balance shaft chain failure, with elevated incidence in high-mileage or urban-driven examples. Porsche internal service data from 1985 noted chain replacements averaging every 130,000–160,000 km under normal conditions, but dropping to 90,000 km in stop-start use. UK DVSA records show strong overall mechanical integrity when maintained, though chain-related noise is a common MOT advisory item. Extended idling and infrequent oil changes accelerate tensioner degradation, making maintenance discipline critical.
Analysis derived from Porsche technical bulletins (1983-1986) and UK DVSA failure statistics (2010-2023). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about PORSCHE M-28-42.
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