Official lightening the mk3 thread!!!!

[xTomKx]

Originally Posted by cars4me89

one thing about drastically changes the weight of the flywheel and size of pullys is that it will make you car run differently and you have to be careful. the flywheel is the rotating mass that keeps the crankshaft and whole engine moving inbetween strokes so if you lighten this you won't have as much mass rotating.. it'll change the balance of the engine.

Lighter flywheels are a popular upgrade. Usually flywheels are balanced separately and then the the whole rotating assemby (crank, flywheel, journal weights - instead of rods and pistons) are balanced.
Therefore in most cases it won't affect the ballance if you use a lighter flywheel assuming it is prebalanced. It will change the critical frequency of the assembly though but most engines never hit their critical frequency anyway.
Besides the decrease in overall weight a lighter flywheel will make the engine spool up much faster. Faster engine spool = more hp.
Does anyone know the weight of a stock flywheel?