I have alot of experience with the wisconsins. I used to run a tjd. The thd is rated at 16hp. Both pistons go up and down at he same time. They will not turn much over stock rpm without coming apart. The tjd pistons alternate.They will turn if setup properly. The tjd is rated at 18hp. The only downfall to the engine besides being so heavy is the single intake port for both cylinders.