Turbochargers and superchargers are based on forced air induction. They basically cram your engine with more air. I will only refer to the word "turbocharger" in this article, but understand that a supercharger works in a similar way, and the difference between them is explained further on.

First off, we need to have a basic understanding as to how an engine works.

If you've ever used a lighter, you already know what happens when you combine a flammable substance with air and a spark. Now if you add more air and more fuel with the same spark you'll get a bigger explosion. Finally if you add more fuel, more air and compress it into a small space, using the same spark, you'll get a rather large and powerful explosion. Take this concept and apply it to the way your engine produces power.

A gasoline engine combines air and fuel into a cylinder, seals it off, compresses it and ignites it. The force of the explosion pushes the piston which in turn pushes the connecting rod, turning the crankshaft and so forth until finally getting to the wheels and tires.

Back to our concept of adding fuel and air to a relatively small space and igniting it... The more fuel and air you can get in the cylinder, the bigger the bang. Have you ever noticed that your vehicle drives much better on a cool evening than on a blistering hot day (let's say your air-conditioning is not on)? This is primarily because cooler air has more molecules in a given area than warmer air. Cooler air means more air molecules compressed in your cylinder, means your computer will inject more fuel into the cylinder, means better combustion and power.

A turbocharger has two main parts: a compressor (hooked up to your engine's intake system) and a turbine (hooked up to the exhaust system). Exhaust coming from your engine gets routed through the turbine section of the turbocharger, spinning the turbine wheel. The turbine wheel is connected to the compressor wheel by a rod, and when the turbine wheel spins, it spins the compressor wheel. The compressor takes in air from the outside (through the air filter) and forces it into the intake of your engine.

The "boost" you get from your turbocharger is measured in psi. Generally a turbocharger will give a boost of between 4-8 psi. With the added air going to your engine, the computer will inject more fuel in as well creating more powerful explosions in the cylinders. This means more power and engine output. That's really all there is to it!

General Questions and Answers:

-So why would someone want an intercooler, does that increase power?

Yes. We've already talked about why cooler air gives you more power than warmer air. An intercooler takes air from the turbocharger and cools it down before it gets to the engine.

-What is turbo lag?

Turbo lag occurs because the turbine is exhaust driven. The delay between when your turbo really kicks in hard, is referred to as "turbo lag".

As your RPM goes up, your engine is working harder & faster, doing more combustion and letting out more exhaust. The more exhaust you have coming out the faster the turbine wheel spins. The faster your compressor wheel spins, the more air you'll get forced into your engine.

At low RPM, your engine is not putting out much exhaust and the turbine wheel doesn't spin as quickly. This means your compressor doesn't spin as quick either and you don't get much more power.

-Are there any downsides to having a turbocharger?

Yes.

Depending on boost, you will generally have to use higher octane fuel to avoid "knocking". Compressing air increases its temperature. Knocking, otherwise known as misfiring, occurs when the fuel and air mixture temperature is too high from compression and it ignites without the spark. Too much knocking will result in engine damage.

Because you are forcing more air and fuel into the same size cylinder (compression is higher) and the explosion at higher RPM is more dramatic, there's more engine wear and tear.

If there's too much boost, your engine components will not be able to handle the pressure and something might end up giving. This could result in things like cracked heads, blown gaskets and broken valves.

-What's the deal with sequential turbochargers?

Generally, this means 2 turbochargers of different sizes. One small and one large. The small one will spin easier, providing you with more power at low RPM and the larger one will kick in at higher RPM. This increases power throughout your RPM range.

-What's the difference between a turbocharger and a supercharger?

Although both are based on the theory of forcing more air into your cylinders, the supercharger is belt driven rather than exhaust driven. The supercharger hooks up to the intake system and is powered by a belt connected to your engine.