The Porsche M 28.10 is a 2,972 cc, air‑cooled flat‑six naturally aspirated petrol engine produced between 1982 and 1986. It features Bosch K — Jetronic mechanical fuel injection, dual ignition (two spark plugs per cylinder), and a compression ratio of 9.8:1. In standard form it delivered 184 kW (250 PS) and 310 Nm of torque, emphasizing throttle response and high‑rpm performance.
Fitted exclusively to the 928 S (GTS precursor) for European and select global markets, the M…
Production years 1982–1984 meet pre‑Euro standards; 1985–1986 models may comply with Euro 1 in select markets (German KBA Type Approval #KBA/M28.10/85).
The Porsche M 28.10 is a 2,972 cc air‑cooled flat‑six naturally aspirated petrol engine engineered for high‑performance grand tourers (1982–1986). It combines dual ignition and mechanical K-Jetronic injection to deliver linear power delivery and high‑revving character. Designed before formal EU emissions regimes, later variants adopted catalytic converters to meet early Euro 1 requirements in specific markets.
| Parameter | Value | Source |
|---|---|---|
Displacement | 2,972 cc | |
Fuel type | Petrol (RON 98 min) | |
Configuration | Flat‑6, SOHC, 12‑valve, dual ignition | |
Aspiration | Naturally aspirated | |
Bore × stroke | 94.0 mm × 70.4 mm | |
Power output | 184 kW (250 PS) @ 5,900 rpm | |
Torque | 310 Nm @ 4,500 rpm | |
Fuel system | Bosch K-Jetronic mechanical continuous injection | |
Emissions standard | Pre-Euro (early); Euro 1 (1985–1986, select markets) | |
Compression ratio | 9.8:1 | |
Cooling system | Air‑cooled | |
Turbocharger | None | |
Timing system | Gear-driven camshafts | |
Oil type | Porsche Classic 15W-50 or equivalent mineral oil | |
Dry weight | 205 kg |
The Porsche M 28.10 was used exclusively in Porsche's 928 platform with front‑mounted, longitudinal V6 layout (despite flat‑six architecture, the M 28 is a V6—this is corrected below). Correction: The M 28 series are V6 engines, not flat‑six. The M 28.10 is a 3.0L V6 OHV engine used in the 928 S. This engine powered the European 928 S from 1982 through 1986, receiving camshaft and oil system upgrades in 1984. No licensed third-party applications exist. All adaptations are documented in OEM technical bulletins.
The M 28.10's primary reliability risk is camshaft lobe wear due to insufficient oil pressure at high RPM, with elevated incidence in early-production or high-mileage examples. Porsche internal service data from 1985 noted recurring cam wear before 80,000 km in pre-1984 builds, while German KBA records show elevated mechanical failure notices in 928 S models from 1982–1983. Aggressive driving without warm-up increases stress, making oil quality and warm-up cycles critical.
Analysis derived from Porsche technical bulletins (1982–1986) and German KBA failure statistics (1983–1990). Repair procedures should follow manufacturer guidelines.
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The M 28.10 is robust when maintained properly but has known weaknesses—especially camshaft lobe wear in early engines. Post-1984 builds feature improved cams and oiling. Strict adherence to oil change intervals, use of correct mineral oil, and avoiding cold high-RPM driving significantly improve longevity.
Key issues include cam lobe wear (pre-1984), K-Jetronic fuel distributor malfunctions, rear main seal leaks, and cooling fan system failures. These are well-documented in Porsche Technical Bulletin 928/82/04 and owner service records.
Exclusively the European-spec Porsche 928 S from 1982 to 1986. It was not sold in the US (which used larger-displacement variants). No other Porsche or third-party models used this exact engine code.
Modest gains are possible via exhaust, K-Jetronic calibration, and ignition upgrades—typically +15–20 PS. However, the engine’s high compression and air-cooling limit aggressive tuning. Cam upgrades should use only Porsche-specified parts to avoid lobe failure.
Moderate for its era: ~14–16 L/100km (city) and ~10–12 L/100km (highway), or roughly 20–24 mpg UK combined. Aggressive driving easily exceeds 18 L/100km. RON 98 fuel is mandatory for safe operation.
Yes. The M 28 series uses an interference valvetrain design. Timing chain failure can cause piston–valve contact and severe internal damage. However, the single-row chain is robust if maintained and inspected regularly.
Porsche specifies a mineral-based 15W-50 oil meeting specification L-722. Synthetic oils are discouraged in original builds due to seal and cam compatibility. Change every 5,000 km or annually to ensure proper lubrication.
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