Diesel Turbocharger Technology

Diesel Turbocharger Technology

New turbocharger designs are helping to improve diesel engine performance.

Tony Martin/Motor Age — The diesel engine would be a shadow of its current self if it weren’t for the turbocharger. Having said that, when was the last time you saw a new diesel that didn’t have a turbocharger? Aside from small tractor engines and the like, the naturally-aspirated (non turbo) diesel has pretty much gone the way of the dodo.

This makes sense, because the turbocharger has made the diesel engine better in virtually every respect. Diesels are now more efficient, produce more torque and horsepower, and have much cleaner emissions than ever before. While a host of technologies have been utilized to make this happen, a good deal of the credit has to go to the turbocharger.

Diesel engines have gotten better over time, and this has been enabled by an evolution in turbocharger technology. Early turbos were limited in their capabilities, and these shortcomings had a proportional negative effect on diesel engine performance. The diesel turbocharger of today is capable of performing across a much broader engine speed and load range, yielding tremendous efficiency and emissions benefits. And we can expect even more from our diesel powertrains as new generations of turbocharger technology are introduced.

Turbochargers are relatively simple machines and are very reliable overall. But like everything else, things can and do go wrong, and automotive service professionals are called on to make them right again. Even if you only work on gasoline engines, turbochargers are becoming more common and you will need to become familiar with them. Let’s start by looking at basic turbocharger operation.

Laws of Physics

A turbocharger is constructed by attaching a turbine to the end of a shaft with a compressor wheel at the opposite end. The turbine is located in the engine exhaust stream, so it sees very high temperatures. This requires the use of materials such as ductile iron for the housing and nickel or titanium alloys for the turbine wheel. The compressor, on the other hand, operates much cooler because it handles filtered air at ambient temperatures. Thus, the compressor end of the turbocharger typically uses aluminum for both the housing and the compressor wheel. The turbocharger may also incorporate a wastegate, which would allow exhaust gases to bypass the turbine wheel if boost pressure rises above a certain threshold. 

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Source: Tony Martin/Motor Age