QUOTE(ChoyChoy @ Mar 2 2008, 03:20 AM)

Hi guys, mind to explain what is a balance shaft?
its a 2 counter-rotating shafts at the bottom of the engine that is constantly rotating at double the engine speed. Its main purpose is to counter the unbalance forces caused by a 4-cylinder engine for a smoother running engine. Most high end sedans with 4-cylinder engines have this. One con is that with these balancer shafts, the engine won't be able to rev too high.
A V10 has the best engine configuration with all the forces balanced at every corner/side. But then how many of us can afford to drive a BMW M5 :)