GM High Value engine

The High Value engine family from General Motors is a group of cam in block, overhead valve V6 engines with cast iron blocks and aluminum heads. They keep the 60 degree bank angle of the 60 degree V6 family they descend from, but a new 99 millimeter bore meant offsetting the bores 1.5 millimeters away from the engine center line. Apart from the LX9, they were the first cam in block engines to use variable valve timing, an innovation that won the 2006 Popular Mechanics Breakthrough Award. For the 2007 model year the 3900 engine offered displacement on demand, also called Active Fuel Management, which shuts down one bank of cylinders under light load to save fuel on the highway. Production was centered on the Tonawanda, New York plant and the Ramos Arizpe plant in Mexico, and GM stopped selling the engines in US market vehicles after the 2012 model year.