How many spark plugs are in a 6 cylinder?
Six spark plugs.
In a typical gasoline six-cylinder engine, there is one spark plug per cylinder, for a total of six. Ignition-system designs vary—some use coil-on-plug units, others rely on coil packs that fire two cylinders at once (a wasted-spark configuration)—but the physical count of spark plugs remains six. In diesel engines, glow plugs replace spark plugs, and you’ll commonly find six glow plugs in a six-cylinder configuration. The following sections outline common setups and noteworthy exceptions.
Baseline gasoline six-cylinder configurations
The following describes the most common ignition layouts you’ll encounter in six-cylinder gasoline engines and how they relate to the six-plug count.
- Coil-on-plug (COP): Each cylinder has its own ignition coil and spark plug, totaling six coils and six plugs.
- Wasted-spark with coil packs: Three coil packs fire two cylinders each, but there are still six spark plugs—one per cylinder.
- Distributorless ignition system (DIS) with multiple outputs: Coils are arranged to deliver a spark to each cylinder’s plug; six plugs are used.
Across these layouts, the number of spark plugs in a standard six-cylinder gasoline engine remains six, even as the coil arrangement changes.
Exceptions and special cases
Some powertrains use different ignition concepts or plug types. Here are the key variations you should know.
- Diesel engines: Do not use spark plugs. They use glow plugs for starting and combustion, and a typical six-cylinder diesel would have six glow plugs.
- Cylinder deactivation or variable firing: Even when certain cylinders are temporarily deactivated to save fuel, the physical plug count remains six, though only a subset may be ignited at any given moment.
- Unusual or performance-focused designs: Some engines may use custom coil configurations, but the plug count is still tied to the number of cylinders—six in a six-cylinder layout.
In short, for a standard gasoline six-cylinder engine, you’ll normally find six spark plugs. In diesel variants, you’ll find glow plugs instead, typically also six in a six-cylinder layout, while the ignition architecture may differ in how the spark (or glow) is delivered across cylinders.
Summary
Across the majority of six-cylinder engines, the spark plug count is six—one plug per cylinder. Ignition-system design (coil-on-plug, coil packs with wasted spark, or distributorless setups) changes how the spark is generated and delivered, but not the number of plugs. If you’re looking at a diesel six-cylinder engine, expect six glow plugs instead of spark plugs.
