I have attached a very interesting article that discusses “V” engine design and the fundementals of balancing engines.
V6 engines which have a fundemental imbalance according to the article are used in many of the passenger cars, mini-vans, and some light duty pick-up trucks sold in North America.
The article is a great read for those interested in the basics of engine balance & design. This article appeared in the December 2010 issue of Car & Driver. Hope you find it informative.
Everything Engines 