A while back,someone made a BB girdle that, looked oversized or poorly made. Had one on a BB that I was building. Assembled the motor and off to the dyno. Motor made about 550HP in those days. Pulled the oil pan and forgot to replace the girdle. Lost 15+/-HP. I made about about 5 to 8 passes before the pan came off. After some head scratching, and oil filter change, got back 12HP. Discovered that I never added the quart or so of oil from the filter change. Assumed that the girdle had some type of scraping effect.