Twin Spark: How does the dual ignition engine work?

Alfa Romeo 16V Twin Spark
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Twin Spark technology is used by Alfa Romeo in its engines. Twin Spark, abbreviated as TS, thus means dual ignition through two spark plugs for each cylinder.

The advantage of dual ignition is the achievement of more optimal combustion and, therefore, higher performance and lower emissions.


History of Twin Spark technology in a nutshell

Twin Spark technology was first used in the Alfa Romeo Grand Prix car in 1914. Twin spark technology was used by Alfa Romeo in its racing cars in the 1960s to allow the engine to achieve higher performance.

Alfa Romeo used TS technology in passenger cars only in the early eighties to increase their performance and help meet stricter emission controls. The first series-produced vehicle with Twin Spark technology was the Alfa Romeo 164 in 1987, which hid a two-liter gasoline engine under the hood under the designation 2.0 TS.

It was an in-line four-cylinder with an eight-valve cylinder head, which was equipped with (for that time) advanced technologies, such as multi-point fuel injection and a valve timing system.

Twin Spark Engines

All engines marked with the abbreviation TS (Twin Spark) are in-line four-cylinder engines with two overhead camshafts (DOHC). Engines using Twin Spark technology have two spark plugs in each cylinder.

1. Twin Spark 8v

Eight-valve TS engines feature an aluminum alloy block and cylinder head, wet iron cylinder liners, and timing chain-driven camshafts. There are two identical spark plugs in each cylinder that ignite the mixture simultaneously.

The spark plugs are between the intake and exhaust valves. Therefore, due to the two-valve design, there is no room for a centrally located (main) spark plug.

2. Twin Spark 16v

The sixteen-valve TS engines feature a heavy-duty cast-iron block with an alloy cylinder head, and a timing belt drives the camshafts. Each cylinder contains one larger and one smaller spark plug. The larger spark plug is located in the center of the cylinder, between the two exhaust and two intake valves, and the smaller spark plug is located on the edge of the combustion chamber.

Spark plugs are lit gradually, which improves the combustion process and increases the compression ratio. The first larger spark plug ignites the compressed mixture, the spark spreads the fire across the entire combustion space, and the second smaller spark plug ignites the mixture from the other side with a slight delay, ensuring a more even burn.

Twin Spark engines have two ignition coils per cylinder. However, one coil serves two spark plugs in a different cylinder. So one coil serves the spark plug in cylinder number 1 and the spark plug in cylinder number 4, and the other serves the spark plug in cylinder numbers 2 and 3. So we need four coils for eight spark plugs.

If one of the coils fails, one of the two spark plugs in the cylinder is still functional. The Twin Spark technology depends on the quality of the spark plugs. Therefore, only high-quality platinum spark plugs with a long service life are used.