Supercharged route to powerful, smaller car engines

A variable-speed supercharger being developed in the

could facilitate the next generation of downsized engines with the performance of larger units, its designer claims.

Reducing engine size is one of the best ways for European carmakers to cut CO2 emissions. But while existing pressure charging techniques such as the use of turbochargers can give downsized engines good performance at high engine speeds, lower speed performance is somewhat compromised, and downsized engines are not always appealing to consumers.

Luke Barker, technical director at Milton Keynes-based Integral Powertrain, explained that the most common form of pressure charging in a downsized engine is via a turbocharger which takes its power from exhaust gases. The problem with a turbocharger is that the delay while exhaust flow builds to a point where effective boost can be delivered is exacerbated in downsized engines.

‘In a turbocharged engine you only get half the peak acceleration to start with and it feels very laggy,’ he said.