Farm stock diesel turbo class

My dad had an 830 Case with those type heads that he put an M&W turbo kit on back in the 80s. He had the local Case dealer install it for him and they did nothing to the injector pump. Just the manifolds and the turbo were added. Before the turbo it would pull a tad over 66 hp. After the turbo it pulled 108 hp. One thing that never made sense to us was if you opened the throttle all the way, it would pull dead on 100 hp on rpm. You could back the throttle down about 100 rpms and crank down the dyno and it would pull 108 hp on rpm every time. It seemed like it was flooding or something. He ran it like that until he sold it to our neighbor and then he ran it like that until the seal went out on the turbo and it started blowing oil everywhere.