From turbo to super

My dads friend had a turbo charger in his 83 320i, and he spent 10 grand upgrading his engine with a management system and a super charger. What is the difference between a super charger and a turbo? Which one is better? I have also noticed it goes pffffff when it changes gears. ITs cool.

Buddy, there is no such thing as "which is better?" it's all on opinion and perspective. A supercharger runs off of the fanbelt of the engine, the supercharger uses power to blow air into the cylinders.

A turbo, uses the exhaust gasses to power the turbine, the turbine blows air into the engine.

The pfft sound, is the sound of the blow off valve, it releases "bad pressure" into the environment, so you don't get roo much turbo lag between shifts. I have heard of blow off valves for superchargers, don't know what they do though.

As you can see, they are both similar except, one runs off of the pressure of the exhaust and the other runs off of the power of the engine itself. Turbos requires time to build up of pressure before it starts spinnning, this is called "turbo lag" , superchargers don't have this problem, but they suck power from your engine at low RPMS.

read those three articles, they should give you a pretty good background in turbos

http://www.automotiveforums.com/vbulletin/showthread.php?t=201348

the third post in that link is a direct comparisson between a super and a turbo

Cool, Thanks

The basic differences are that turbochargers have better fuel consumption and higher torque outputs (power = torque*angular velocity) compared with superchargers. The downside with the turbocharger is the lag and that they don't work under a certain rpm.

If a positive displacement supercharger is used we will basicly keep the NA torque curve but increase it. If we use a centrifugal typ of supercharger the boost will increase at higher engine speeds, this means that the torque curve will do the same.
A turbocharger will keep the NA torque curve until the turbocharger can deliver boost, then the torque will increase (higher than compared with superchargers for the engine speed which they are matched to) and then it will start to decrease when the turbocharger get out from the range where it's most efficient.

When designing for high power we want torque at high speeds, torque at low speed is basicly just wanted for driveability.

also read the thread called "new thread starters read this" or something, it will tell you how to use this site well. considering how many threads on this subject there are, you should really read it.