The 6.0L LQ9 is a more powerful evolution of the LQ4, developed for Cadillac's luxury sport utility vehicles. It features increased power output achieved primarily through the use of LQ9-specific: flat-top pistons, rods, crank, and beefier pushrods that increase the compression ratio from 9.4:1 (for the LQ4) to 10.0:1. The block and heads are common with the LQ4.
Originally referred to as the “Vortec H.O. 6000”, in 2006 the LQ9 was renamed the “Vortec MAX” to underscore its being the most powerful light duty V8 in GM’s truck line at that time. The 2006+ engine “vanity” cover displays new “Vortec MAX” badging.