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Turbos, biturbos, triturbos, superchargers and the rest: Which engine charging approach is best?

Whether you like it or not, modern engines are charged. Which approach is best? We've had a look at what's on offer.

Five years ago, this story would have been written very differently. We would have dissected V12s, paid homage to the piston acceleration of the V10, enthused about the maximum revs of the V8 and applauded all their guttural noises. The irretrievable good old days... At least, they are if you’re buying a new sports car. You’d be hard pressed to find one without some form of engine charging, not because of any intrinsic superiority, but due to a mounting range of external factors...

The consumption cycle – the driving force behind turbomania

“The NEDC consumption cycle is the primary driving force behind the swap over to turbochargers – it’s a matter of consumption and emissions”, according to Professor Thomas Koch, chief of the Institute for Piston Engines at the Karlsruhe Institute for Technology (KIT). Even though the NEDC cycle is on its way out, its intended purpose remains, and will become even more extreme in the future; concepts such as particle filters for direct injection turbo engines and real driving emissions are increasing pressure on new engines – in every sense.

These circumstances mean that car manufacturers have no choice but to now employ engine charging for their sportier engines, as this improves efficiency and fuel consumption (measured in g/kWh), both through the reduction in engine size and the more frugal consumption behaviour of these engines under partial load. It is, however, a loss from the viewpoint of sports car fanatics, but a loss we must deal with and move on. This trend isn’t going to be an overnight craze.

Turbo engines with naturally aspirated performance

Our technical expert Professor Hans-Jörg Bauer, head of the Institute for Thermal Turbomachines at the KIT, believes emulating the classic strengths of naturally aspirated engines through turbocharging – such as high torque, direct throttle response and better dosing of power – will be a development goal of increasing priority.

There is however one point which could be more difficult than the rest: “turbochargers have one decisive weakness – they can’t reproduce that same emotive sound experience, as the turbo itself acts as a silencer”, explains Professor Hans-Jörg Bauer. The question is then, whether fans will be able to come around to the concept of sound engineering. Our question for today however is what the engines of today can achieve in terms of emulating their more voluminous brethren

Different charging methods on test

In order to answer this, we chose ten cars with sporty engines using the following variety of charging methods: turbo compressor, turbo on a low/high capacity engine, supercharger, triturbo, biturbo with electronic compressor and biturbos with engines of various capacity).

We then measured, tested and discussed the different concepts with our experts from the Karlsruhe Institute of Technology.

These, and our initial thoughts, can be found in the image gallery.

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Mercedes-Benz Cars

Date

3 March 2016
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