An internal combustion engine is fitted with a pre-combustion chamber having first and second electrodes, each electrode extending through a respective electrode aperture located in a thermally conductive body portion of the pre-combustion chamber body which is located within the cylinder head or other engine body component outside the combustion chamber. The second electrode may be a ground electrode and is adjustable along an axis of the respective, second electrode aperture to adjust the spark gap.

An internal combustion engine is fitted with a pre-combustion chamber having first and second electrodes, each electrode extending through a respective electrode aperture located in a thermally conductive body portion of the pre-combustion chamber body which is located within the cylinder head or other engine body component outside the combustion chamber. The second electrode may be a ground electrode and is adjustable along an axis of the respective, second electrode aperture to adjust the spark gap.

In a spark plug, a discharge gap is formed between a ground electrode and a central electrode. The ground electrode has a rod-shaped part and an opposing part. The opposing part faces the central electrode, and has a flat surface part and a slope surface part. The slope surface part is formed on a part of the opposing part in an extending direction of the ground electrode, and formed on the opposing part and gradually separated from the central electrode along a width direction of the opposing part. The spark plug has a ratio V/W within a range of 0.5<V/W<2.0. V indicates a length of the opposing part measured in a gap formation direction in which the central electrode, the discharge gap and the opposing part are arranged in order. W indicates a length of the opposing part in the ground electrode width direction.

In a spark plug, a discharge gap is formed between a ground electrode and a central electrode. The ground electrode has a rod-shaped part and an opposing part. The opposing part faces the central electrode, and has a flat surface part and a slope surface part. The slope surface part is formed on a part of the opposing part in an extending direction of the ground electrode, and formed on the opposing part and gradually separated from the central electrode along a width direction of the opposing part. The spark plug has a ratio V/W within a range of 0.5<V/W<2.0. V indicates a length of the opposing part measured in a gap formation direction in which the central electrode, the discharge gap and the opposing part are arranged in order. W indicates a length of the opposing part in the ground electrode width direction.

System and methods for operating a vehicle that includes a boosted engine are described. In one example, a spark plug may be adjusted between two operating states to reduce a possibility of pre-ignition and spark plug fouling. A first operating state may be conducive to operating the engine at light loads. The first operating state may be conducive to operating the engine at higher loads.

An internal combustion engine is fitted with a pre-combustion chamber having first and second electrodes, each electrode extending through a respective electrode aperture located in a thermally conductive body portion of the pre-combustion chamber body which is located within the cylinder head or other engine body component outside the combustion chamber. The second electrode may be a ground electrode and is adjustable along an axis of the respective, second electrode aperture to adjust the spark gap.

An internal combustion engine is fitted with a pre-combustion chamber having first and second electrodes, each electrode extending through a respective electrode aperture located in a thermally conductive body portion of the pre-combustion chamber body which is located within the cylinder head or other engine body component outside the combustion chamber. The second electrode may be a ground electrode and is adjustable along an axis of the respective, second electrode aperture to adjust the spark gap.

A spark plug, including a housing, an insulator situated in the housing, a center electrode situated in the insulator and a ground electrode situated on the housing, the ground electrode and the center electrode being situated relative to one another in such a way that the ground electrode and the center electrode form a spark gap, and the ground electrode including a core and a sheath surrounding the core, the core being made of a material which has a higher thermal conductivity than the material of the sheath, and a cross sectional area of the ground electrode being not greater than 2.76 mm.sup.2, the sheath having a wall thickness c of not greater than 0.4 mm in a first region of the ground electrode.

A center electrode is electrically coupled with a main terminal. A ground electrode is opposed to the center electrode to form a gap therebetween. A piezo actuator changes in length on application of a voltage. The piezo actuator actuates one of the center electrode and the ground electrode to manipulate the gap.

A center electrode is electrically coupled with a main terminal. A ground electrode is opposed to the center electrode to form a gap therebetween. A piezo actuator changes in length on application of a voltage. The piezo actuator actuates one of the center electrode and the ground electrode to manipulate the gap.