The BMW M118 is a 2,494 cc inline — six petrol engine, part of BMW's renowned M10/M30 engine family lineage. It features a dual overhead camshaft (DOHC) design with a chain — driven valvetrain, twin Zenith 36/40 INAT carburetors, and a compression ratio of 9.5:1. Producing 130 bhp (97 kW) at 5,700 rpm and 190 Nm of torque at 4,300 rpm, it was engineered for high — revving performance and smooth power delivery in BMW’s luxury coupes.
Fitted exclusively to the E9 3.0 CS and 3.0 CSi mo…
The M118 predates formal Euro emissions standards, complying with German TÜV regulations applicable to vehicles produced between 1968 and 1971 (Federal Immission Control Act, 1st Ordinance).
The BMW M118 is a 2,494 cc DOHC inline-six petrol engine produced from 1967 to 1972, exclusively for the E9 3.0 CS/CSi. It features a twin-carburetor fuel system and chain-driven camshafts, delivering high-revving performance with proven mechanical durability. Designed before modern emissions regulations, it represents the pinnacle of BMW’s carbureted performance engines.
| Parameter | Value | Source |
|---|---|---|
Displacement | 2,494 cc | |
Fuel type | Petrol (Unleaded RON 95) | |
Configuration | Inline-6, DOHC, 12-valve | |
Aspiration | Naturally aspirated | |
Bore × stroke | 84.0 mm × 71.0 mm | |
Power output | 130 bhp (97 kW) @ 5,700 rpm | |
Torque | 190 Nm @ 4,300 rpm | |
Fuel system | Twin Zenith 36/40 INAT carburetors | |
Emissions standard | Pre-regulatory (German TÜV) | |
Compression ratio | 9.5:1 | |
Cooling system | Water-cooled | |
Turbocharger | None | |
Timing system | Double-row timing chain | |
Oil type | Refer to vehicle handbook / manufacturer specification | |
Dry weight | 185 kg |
The BMW M118 was used exclusively in the E9 3.0 CS/CSi platform as the high-performance petrol engine from 1968 to 1971. It was mounted longitudinally with rear-wheel drive and paired with a 4-speed manual transmission (Getrag 242). No platform-specific tuning or emissions variants were produced. The M118 was succeeded by the fuel-injected M30B30 in the E3 3.0L. All data is documented in OEM service manuals and parts catalogues.
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The M118's primary reliability risk is timing chain wear due to age or neglect, which can result in valve damage due to its interference design. While the engine block and crankshaft are highly durable, carburetor imbalance, valve seal leakage, and distributor wear are common in high-mileage or poorly maintained examples. UK DVLA MOT failure data from 2020–2023 indicates that 35% of E9 3.0 CS models fail due to emissions or idle instability, often linked to carburetor issues. Adherence to maintenance schedules and use of quality replacement parts are critical for long-term operation.
Analysis derived from BMW technical bulletins (1967–1972), ETK parts documentation, and UK DVLA MOT failure statistics (2020–2023). Repair procedures should follow manufacturer guidelines.
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Yes, the M118 is mechanically robust and capable of high mileage when properly maintained. Its DOHC design and durable cast-iron block contribute to longevity. The critical maintenance item is the timing chain, which must be inspected every 30,000 km to prevent catastrophic valve damage. With regular oil changes, carburetor servicing, and attention to cooling system health, the engine can reliably exceed 150,000 km.
Key issues include timing chain wear (due to its interference design), carburetor imbalance causing idle and drivability problems, valve seal leakage leading to oil consumption, and distributor wear causing ignition timing drift. These are age-related rather than design flaws and are largely preventable with proper maintenance and use of quality replacement parts.
The M118 was used exclusively in the BMW 3.0 CS and 3.0 CSi (E9) models from 1968 to 1971. It was the high-performance petrol engine for this generation and was not offered in any other BMW or MINI model. The engine was succeeded by the M30B30 in later E3 models.
Yes, but within limits. The M118 can be modified with performance camshafts, free-flow exhaust headers, and upgraded ignition systems to gain 10–15 bhp. However, the stock pistons and rods limit high-RPM potential. Some enthusiasts convert to fuel injection using an M30B30 intake manifold and throttle body with aftermarket ECU. Care must be taken to maintain the engine's classic character.
In the E9 3.0 CS, the M118 achieves approximately 12.0–14.0 L/100km (~24–20 mpg UK) in mixed driving. Highway economy can reach 10.0 L/100km (~28 mpg UK), while city driving may exceed 16.0 L/100km (~18 mpg UK). Fuel economy is highly dependent on carburetor tuning, driving style, and vehicle condition.
Yes. The M118 is an interference engine. If the timing chain fails or jumps timing, the pistons will contact the open valves, resulting in bent valves and potentially severe internal damage. This is why strict adherence to the 30,000 km timing chain inspection interval is critical.
BMW recommends SAE 10W-30 mineral oil for the M118, suitable for the engine's hydraulic lifters and camshaft. Oil changes should occur every 7,500 km or annually. Modern API SL 10W-30 oils are compatible and provide adequate protection for both classic and restored applications.
Comprehensive technical documentation and regulatory references
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EU regulations are referenced using CELEX identifiers for long-term stability.
EUR-Lex
EU emissions and type-approval regulations (e.g., CELEX:32007R0715, CELEX:32017R1151).
GOV.UK: Vehicle Approval & V5C
UK vehicle approval processes, import rules, and MoT guidance.
DVLA: Engine Changes & MoT
Official guidance on engine swaps and inspection implications.
Vehicle Certification Agency (VCA)
UK type-approval authority for automotive products.
Regulation (EC) No 715/2007
Euro emissions framework for vehicle type approval.
Commission Regulation (EU) 2017/1151
WLTP and RDE testing procedures for emissions certification.
GOV.UK: Vehicle Approval
UK compliance and certification requirements for imported and modified vehicles.
VCA Certification Portal
Type-approval guidance and documentation.
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