Physics help from experts.

## Physics Tutorials

### Turbochargers and Making Horsepower

The internal combustion engine works by igniting an air to fuel ratio inside a combustion chamber. This combustion forces the pistons down, which then moves your vehicle. A turbocharger compresses the air flowing into the engine, allowing more fuel to then be added, in turn creating more combustion inside the engine, making more power.

A turbocharger works by using the engine's exhaust flow to spin a turbine. This turbine is connected to a shaft attached to another turbine which draws in fresh air. The second turbine is acting like a compressor, and forces the air into the combustion chamber of the engine. The air going in is known as boost, and is usually measured in pounds per square inch.

Now that there is more air in the combustion chamber, more fuel is added, and you create a bigger combustion when the mixture is ignited, considerably increasing the power made. The more exhaust that goes into the exhaust turbine, the faster it will spin the compressor turbine, resulting in more air into the combustion chambers, and more power. The speed of the turbo is regulated by a wastegate, which routes exhaust gases around the turbo, to keep the turbo from reaching to high of speeds, which would result in too much boost. An engine running too much boost can be damaged.

Normal atmospheric pressure is 14.7 psi at sea level, so if you run 14.7 psi of boost, theoretically your horsepower will be doubled. Due to some inefficiencies of a turbocharger though, you will be making about 80 percent more horsepower.

#### Application

You have decided that you would like to improve the power of your vehicle, but do not want to add the weight of a bigger engine, and you don’t have a lot of room to spare in the engine compartment. You know that the more air and fuel an engine can burn, the more power it will make. A good choice would be to install a turbocharger. They only add about fifteen pounds of weight, and take up little room under the hood. There are many kits available to install a turbocharger onto a vehicle that was not equipped with one to begin with, and a lot of reading material available to help with the install. Now that you know that turbochargers greatly increase your power with few drawbacks, happy boosting.

#### Question

What types of things will limit how much boost you can run?

Answer: Things that will limit how much boost you can run are the strength of the engine's internal parts such as connecting rods, pistons, and crankshaft. A good way to strengthen them is replacing them with forged parts, as opposed to cast parts. The amount of compression your engine has will limit how much boost you can run, as having too much compression with too much boost can cause detonation, which will damage the engine.

Gregory Shepertycky