P.S. on Porsche 924 and Mitsubishi

[Marshall Barrett <barrett@ral.mindspring.com>]

Porsche licenses the technology for the balance shafts from Mitsubishi.  The
engine design was all Porsche. 
They are NOT integral to the engine design.  In fact they are not even
necessary.  The purpose of balance shafts is to cancel out the natural
dynamic vibration of an inline 4 cylinder engine. Once the engine gets
larger than 1.6 or 1.7 liter, the vibration gets really obnoxious. The
balance shafts do not cancel the vibration, they just counter balance the
vibration.  The dynamics of the vibration are still there. 
At Brumos, we removed the balance shafts from the race cars, cause the
engine was solidly mounted, they eat energy, add weight, and we really
weren't concerned about making the ride comfortable!

Marshall Barrett