I found this review of the Harbor Freight Predator V-Twin on homebuiltairplanes.com while looking for info on oil filters. The reviewer actually tore the engine down that he received. Some of his findings are interesting. Obviously an engine for an aircraft is critical. http://www.homebuiltairplanes.com/forums/firewall-forward-props-fuel-system/21130-22-hp-harbor-freight-engine-evaluation-other-v-tiwns.html