Turbochargers are often associated with high performance cars, race cars and big diesel engines. More often called a turbo, this is a type of forced induction which uses the exhaust gases to add more air back into the combustion chamber. This leads to a significant increase in power output that does not add too much weight to the engine. Compared to a naturally aspirated engine of the same displacement, a turbocharged engine produces more horsepower.
At the heart of a turbo system is the turbine which has two sides; one that is turned by the exhaust gases from the engine and another that is used as an air pump to pressurize the air going back into the engine through the intake. To reduce the temperature of the compressed air, an intercooler is placed between the compressor and the intake manifold. A turbocharger is very useful but it has its weaknesses as well. Here are the advantages and disadvantages:
More power than an engine that runs on natural air, which translates to more output without the need for increased displacement. In addition, torque is also increased which is very useful in acceleration and heavy loads. Turbos are more efficient compared to naturally aspirated and even supercharged engines. Compared to blowers, turbos are smaller, lighter and easier to install. Turbochargers are also more fuel efficient when compared to N/A engines with comparable power output.
The most popular weakness of turbos in general is turbo lag. This is most evident in large turbos, where they may put out more power but need more air to spin which translates to more time needed to spool up. Since turbos are driven by the exhaust, the power curve is not linear and it can be quite short; as such it is often considered an on/off switch. Cost is also one of the greatest disadvantages of a turbo, especially in aftermarket applications and as a power add-on. When you want to add a turbo to your NA engine, you will need a complex system. Sometimes you have to strengthen the motor for the extra pressure on the pistons, connecting rods and even the engine block.
New Generation Turbos: The Return of the Turbocharger
Those are the widely accepted benefits and drawbacks of a turbocharger. Lately, turbos have reemerged after being put on the wayside by maintenance and emission concerns. Government concerns about fuel efficiency and pollution associated with large displacement, multiple cylinder engines have placed pressure on manufacturers to go back to the turbo. These new generation turbo engines have less lag, decreased heat and lower emissions. The variable geometry turbochargers, such as those produced by Porsche, keep the turbines spooled across the rev range, hence lag is no longer an issue. Nowadays, large V8s have been replaced with turbocharged four and six cylinder options. Even turbo-diesels are putting out more horsepower without using so much fuel and producing too much smoke.
Global warming and climate change has changed the auto racing landscape, with Formula One cars, World Rally cars, and Touring cars now running on smaller, turbocharged engines. It is safe to say that turbos are back and high-revving, gas-guzzling, large displacement engines are under the threat of extinction.