Why Mercedes Fires Its Spark Plugs Five Times per Stroke
In its latest generation of engines, Mercedes uses a technology called “Multispark ignition,” where each spark plug is fired multiple times (five, to be exact) when igniting the air-fuel mixture inside the cylinder. Why, you ask? Well, it all has to do with efficiency. Jason Fenske of Engineering Explained is here to tell us all about it.
Under low engine loads, it’s more beneficial to use a lean air-fuel ratio (that is, there’s a lot more air in the mixture than there is fuel). In this situation, it can be difficult to start ignition quickly because of how spread out the fuel is within the cylinder. Mercedes’s Multispark ignition system alleviates this problem by simply firing the spark plug more than once per stroke. This creates a bigger flame from the plug, which means less ignition delay, and faster combustion overall.
According to Mercedes, this tech alone is good enough for a two percent gain in efficiency for the engine. That may not sound like much, but over long periods of time, it adds up. Check out his full explainer video, featuring the Mercedes-AMG GLC63, right here.