European carmakers feel that turbocharged small engines are the way of the future, to increase fuel economy and reduce emmissions.
Instead of using a big normally aspirated engine, a small capacity engine with a turbocharger is used so that fuel economy and emmissions is lower, but the turbo can give that required surge of power whenever maneuveres such as overtaking are required. So the engine only behaves like a larger displacement engine when you want it to. Sounds pretty logical right?
An example of this new trend is Volkswagen’s new twin-charged TSI engine, which uses a supercharger and a turbocharger on a 1.4 litre petrol engine. This engine first debuted on the Volkswagen Golf GT.
However turbochargers have some downside. Diesels have been turbocharged for a long time now. Almost all diesels are turbodiesels. It’s easier to make a turbodiesel as diesel exhaust gas temperatures are lower, at about 750-800 degrees celcius. A normal gasoline engine’s exhaust gas temperature is over 1000 degrees celcius, and will be even hotter if it’s turbocharged. Turbos also cannot run for long durations.
More R&D has to be done on materials to withstand the turbocharging effects such as higher temperatures before this new way of designing engines can be mainstream.