Full-load operation can be enough to make common turbocharger constructions with a steel housing glow red all over, however, the aluminium turbine housing keeps a cool head. "The double-walled aluminium housing surrounds the hottest area with a cooling water jacket," says Schwerdel.

The coolant flowing through this jacket ensures that the external housing surface does not get hotter than 120°C (248°F) and the internal temperature does not exceed 350°C (662°F), which Udo Schwerdel explains has not one, but two benefits: "First, much less effort is required to protect neighbouring components from the heat. Second, cooling of the exhaust flow reduces the thermal load on the catalytic converter, meaning it hardly ages at all." At the same time, the dynamic response of the electric actuator at the wastegate ensures that the catalytic converter heats up quickly.

In keeping with the modular principle given by the customer, the turbocharger is tightly integrated in the engine (it is a fixed component of the exhaust manifold), but Continental turbochargers with a steel housing can also be attached to the same base engine using the interface on the cylinder head. The car manufacturer is using this option for high-performance engines as well as vehicles for export to hot countries. The bearing housing is cooled from inside the turbocharger for steel variants, while cooling from outside is sufficient for aluminium turbochargers.

In the MINI, 1.2kg of weight is saved per aluminium turbocharger. Since reduced weight also means reduced fuel consumption, the lightweight material supports the fuel consumption and emission targets of the automotive industry. Despite the additional expenditure for the water cooling, aluminium turbochargers are more affordable for automotive manufacturers.

"High-temperature-resistant materials such as nickel-base alloys drive up prices for turbochargers with steel housings," says Schwerdel, "whereas our aluminium alloy is a cost-effective material."
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