How Does a Turbo Work?

An internal combustion engine relies on airflow to run properly, as well as the correct amount of fuel to create the combustion process. Through natural aspiration, an engine relies on the pressure differences created by the intake valves opening and closing, which creates airflow into the combustion chamber.

With the progress of technology and the pursuit of increasing efficiency in an engine, there are many ways to increase performance in an engine besides increasing its displacement. One of those technologies is turbocharging.

How Does a Turbo Work?

A turbocharger is a centrifugal-style power adder that uses exhaust gas pressure, volume and temperature to spin a turbine in the exhaust stream. The main components of a turbocharger are the turbine, turbine housing, center-bearing support, compressor and compressor housing.

The turbine is linked with a shaft to the compressor wheel, which compresses the air charge before entering the engine. When an engine is running, pressure differences are created by the action of moving pistons and opening valves. When the exhaust valve opens, the high-pressure, high-temperature pulse exits the combustion chamber and is routed to the turbine housing of the turbocharger.

As the air passes through the housing, the exhaust pulse rotates the turbine, which in turn spins the compressor wheel. The compressor wheel performs two functions — first, the vanes of the wheel pull in the intake air, and then the vanes use centrifugal force to push the air into the compressor housing.

When the air is pushed into the compressor housing, it becomes pressurized due to the volume of air and centrifugal force. When enough volume is being forced through the compressor, it reaches a point where it overcomes the engine’s cubic-inch displacement and beings to create a positive pressure in the intake manifold.

When this happens, boost is created. When there is more air available to the engine, the engine can use more fuel. With more fuel and air compressed in the combustion chamber, the pressures are greater, which pushes the pistons down harder and faster, thus creating more power!

There are two common ways to control boost pressure on a turbocharger:

• Wastegate: The wastegate is a valve in the exhaust side of the turbo. It opens to allow exhaust gases to bypass the turbine housing. These can be externally mounted or cast into the turbine housing.
• Blow-off valve: A blow-off valve (BOV) is placed in the intake air stream to control and relieve pressure before entering the engine. This valve opens when the throttle blade is closed to prevent surge.

Turbochargers are a great way to improve performance in an internal combustion engine without putting the engine under more strain. Since a turbocharger relies on exhaust gases to operate, there is no mechanical connection to the engine. One thing to keep in mind is that anything the engine must rotate requires some degree of engine power to operate.

What Does a Turbo Look Like?

Wondering what a turbocharger looks like? The actual unit looks like a pair of snail-shaped fans:

Things to Know Before Installing a Turbocharger

Installation of a turbocharger on an engine can be fairly easy. However, there are many factors to consider for your particular engine build before applying all of that extra air, including:

Base engine components

Original equipment manufacturers typically use cast-aluminum pistons, powdered steel connecting rods and cast-iron crankshafts. While these parts are reliable on naturally aspirated engines, their strength will be compromised when adding boost to an engine.

Depending on your build, forged-aluminum pistons and connecting rods might be recommended. Steel crankshafts are available in the aftermarket and are much stronger than cast iron.

Intercooler

When air is compressed, the temperature of the air increases as well. The major issue with hot air temperature is that the density of the oxygen molecules is spread farther apart, which can dramatically affect your power output.

To combat this increase in temperature, an intercooler should be used to lower air temperatures before they enter the engine. The drop in temperature will also reduce the risk of engine knock and detonation, which can be very destructive to your engine!

Extra Fuel Supply

When you add more air to an engine, more fuel will be required to maintain efficient combustion. In some cases, your factory fuel system may not be able to keep up with the needed fuel supply. High volume fuel pumps, larger fuel lines and adjustable fuel-pressure regulators can ensure you have ample fuel available to the engine under all load commands.

Computer Tuning

With newer vehicles that are computer controlled, it’s a bit more difficult to be able to compensate for increases in airflow. There are many aftermarket companies that provide flash tunes and programmers that help ensure an engine management system can keep everything in check.

Regulations

One thing that is important to check before installing a turbocharger is to make sure it’s legal to do so in your area. California, for example, has emissions regulations that require the use of certain parts if turbos are going to be added. Be sure to look up the laws and regulations in your area!