The torque output of a starter is the most important consideration. The starter must be able to spin the engine, and do it without overheating internally. Since there
is no such thing as having too much torque -even on a street vehicle - a 200 ft.lb. starter will work for everyone. Speaking in general terms, a over 12:1 compression or higher engine should use a 200 ft.lb. starter. Engines up to 12:1 should use at least a 180 ft.lb. starter. 160 ft.lb. starters are good for engines up to 10.5:1.
One thing to keep in mind is that the torque characteristics of a starter are a function of its design. High voltage batteries or
low internal resistance batteries will affect the kilowatt output of the starter by changing the output speed but not the torque. Therefore, buy enough torque to begin with.