Four diamonds on each head enable the StoneGrind 3000 to be pushed faster and increase production by 40% compared to electric machines. It sports a Robin/Subaru 22-hp, 653 cc propane engine, two vacuum ports, and three 13-inch counter-rotating heads for a total grinding width of 30 inches. Polishing can be stopped at 800 grit, rather than the typical 3000 grit, while attaining the same results. Eagle Solutions. 770-773-3875.