Twin spark

Twin spark:
Twin spark is the name that Alfa Romeo uses for their engines that are equipped with 2 spark plugs per cylinder. In a twin spark engine, 2 different types of spark plugs are mounted per cylinder: namely the centre spark plugs and the side spark plugs. This can be seen in the images below. Thanks to this technology, injection can be done in a different way (the combustion is not limited to just directly below the spark plug), resulting in combustion over a larger surface area.
This mainly benefits the power output. Especially older Alfas could easily have a 1.4 engine with relatively high power compared to other cars. In Italy, road tax is determined by the engine displacement, which is why there was experimentation with getting more power from a smaller engine capacity in this way.