Everything you wanted to know about Turbo's

Turbocharging

What comes out of your exhaust pipe is waste product. In a normally aspirated non-turbo engine the gas fires down the exhaust pipe containing lots of momentum and then escapes into the atmosphere, doing its bit for pollution on the way. If you pass this fast moving gas through a cast iron passage containing a turbine wheel, it makes it spin. If you connect that via a common shaft to another wheel with propellers closely fitted in an aluminium housing, it would suck air in, throw it against the walls due to centrifugal force, squash it and then force it out the other side. Now the air is pressurised and travelling much faster. In effect you have created an air pump which is called a compressor. Connect this to a tube feeding your engines induction system and you have instantly got a supply of as much compressed air as your engine can handle. The more quickly you spin the turbines, the more air you get in and the faster your car will go.

This is the principle of the turbo charger, the compressed air and product called the boost. This gives you lots of horsepower and torque. It isn't as simple as it sounds because you need a method of regulation. If you carried on spinning the turbine, you would create endless boost pressure, eventually blowing everything up! As a result, when the compressor reaches the required level, an actuator on the side of the turbo pushes a door open in the turbine housing called the wastegate. The exhaust gas is then rerouted down the exhaust pipe, the turbo stops spinning and the boost stops.