Performance question

What's the difference between a supercharger and a turbo.

A supercharger runs off a belt connected to the engine. Which makes it kick in earlier but you don't gain as much power because the belt on the engine has to power the charger.

A turbo charger runs off the exhaust, it takes more time to get spinning because it needs enough exhaust to spin-up but it is easier on the engine.

Check out www.howstuffworks.com for a more detailed description.

Which costs more and which gives out more power?

For a BMW the turbo's average a bit higher. AA's turbo kit for my car is $13,000. RMS Supercharger around $6000.

From a kit, it'd be pretty close price wise. There are millions of pros and cons for each option.

A turbo kit might be more expensive but their aftermarket availability is huge so many can be salvaged and modified onto some custom extractors with an aftermarket ECU (prolly get it done for less than 4k US).

A Turbo will yeald greater power increases, but also greatly raises under-bonnet temperatures, and can greatly reduce the life of your engine (without good fueling). A supercharger cannot run the boost a turbo can (or not as easily), and weighs more, but it's appeal lies in it's ability to apply power low in the rev range and reduced temperature. Kits are available for both.