The Porsche M28.11 is a 2,849 cc, water-cooled V6 petrol engine produced between 1982 and 1986. It features a 90‑degree V6 layout, Bosch K-Jetronic mechanical fuel injection, and a single-row timing chain driving dual overhead camshafts per bank. Output was rated at 132 kW (180 PS) @ 5,600 rpm and 235 Nm of torque, engineered for smooth mid-range delivery in front-engine applications.
Fitted exclusively to the Porsche 924 Carrera GT and limited 944 models for homologation purposes, the M28.11 was developed to meet FIA Group B requirements while maintaining road usability. Emissions compliance was achieved through exhaust air injection and lean-burn calibration, meeting EU Directive 70/220/EEC standards (pre-Euro 1) in European markets.
One documented concern is premature wear of the timing chain tensioner rails, leading to slack-induced cam timing drift. This issue, highlighted in Porsche Technical Service Bulletin 944/TSB/84-03, was attributed to material fatigue in early phenolic tensioner guides under sustained high-RPM use. Revised nylon-reinforced rails were introduced in mid-1984 production.
Production years 1982–1986 meet EU Directive 70/220/EEC (Euro pre-1) standards depending on market (VCA Type Approval #VCA/EMS/6321).
The Porsche M28.11 is a 2,849 cc 90-degree V6 petrol engine engineered for high-revving GT applications (1982–1986). It combines Bosch K-Jetronic mechanical injection with dual overhead camshafts to deliver linear power and race-derived responsiveness. Designed to meet pre-Euro emissions thresholds, it prioritizes mechanical simplicity and serviceability over electronic control.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 2,849 cc | |
| Fuel type | Petrol (RON 95 minimum, RON 98 recommended) | |
| Configuration | V6, DOHC, 24‑valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 89.0 mm × 76.0 mm | |
| Power output | 132 kW (180 PS) @ 5,600 rpm | |
| Torque | 235 Nm @ 4,200 rpm | |
| Fuel system | Bosch K-Jetronic mechanical continuous injection | |
| Emissions standard | EU Directive 70/220/EEC (pre-Euro 1) | |
| Compression ratio | 9.7:1 | |
| Cooling system | Water-cooled | |
| Turbocharger | None | |
| Timing system | Single-row chain with hydraulic tensioner and phenolic/nylon guides | |
| Oil type | SAE 10W-40 synthetic (Porsche A40 spec) | |
| Dry weight | 168 kg |
The DOHC V6 provides smooth high-RPM power ideal for spirited driving but requires precise K-Jetronic calibration to avoid lean misfires. Strict 10,000 km oil changes with high-detergent 10W-40 oil are essential to protect the chain tensioner and cam journals. Early M28.11 units (pre-06/1984) should have tensioner rails upgraded per TSB 944/TSB/84-03 to prevent timing drift. The absence of catalytic converters allows use of leaded-compatible fuels, though unleaded RON 98 is recommended for valve seat longevity. Cold starts rely on proper warm-up regulator function—common failure point in aged systems.
Oil Specs: Requires Porsche A40–compliant 10W-40 with high detergent content (Porsche Lubricants Bulletin LB-83-05). ZDDP beneficial for cam lobe protection.
Emissions: EU Directive 70/220/EEC applies to all production years (VCA Type Approval #VCA/EMS/6321). No catalytic converters fitted.
Power Ratings: Measured under DIN 70020 standards. Output assumes RON 98 fuel and correct control pressure (Porsche TIS Doc. M28-TB-1984).
Porsche Technical Information System (TIS): Docs M28-TB-1982, FI-82-07, M28-TB-1984
Porsche Technical Service Bulletin 944/TSB/84-03
VCA Type Approval Database (VCA/EMS/6321)
EU Directive 70/220/EEC
The Porsche M28.11 was used exclusively in the Porsche 924 platform with front-engine, longitudinal mounting and no external licensing. This engine was developed specifically for the homologation-special 924 Carrera GT and select 944 Competition variants, featuring dry-sump lubrication, higher compression, and race-tuned exhaust. From 1986, the M28.11 was superseded by the M44/40 in the 944 S. All adaptations are documented in OEM technical bulletins.
Engine type ‘M28.11’ is stamped on the front timing cover near the crank pulley (Porsche WIS 115.02). The presence of dual cam covers with ‘DOHC’ castings and K-Jetronic fuel distributor (Bosch 0 438 100 009) confirms identity. VIN 7th digit ‘G’ denotes Carrera GT. Critical differentiation from standard M20 engines: M28.11 uses 24-valve heads, external oil cooler, and dry-sump system with scavenge pump on the right bank. Service parts for timing and valvetrain are not interchangeable with M20 or later M44 engines (Porsche TSB 944/TSB/85-11).
The M28.11's primary reliability risk is timing chain tensioner rail failure, with elevated incidence in high-RPM or track use. Porsche internal service data (1985) indicated timing repairs in over 15% of early-build units before 90,000 km, while DVSA historic MOT reports cite frequent idle instability and emissions faults in UK-registered examples due to degraded K-Jetronic components. Sustained high-load operation without rail upgrades makes timing integrity and fuel calibration critical.
Analysis derived from Porsche technical bulletins (1982–1986) and UK DVSA historic MOT failure statistics (1990–2022). Repair procedures should follow manufacturer guidelines.
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