flipflop...you have a good point. There is a lot of engines with far more power than this one and that same center piece is holding a complete flywheel and extension with bolt. prop washer and prop and I have not heard of any coming loose yet. No one is going to be in front of or in line of any prop set-up of mine, or one I buy. If it explodes in air...so be it. I have seen a engine come off a airplane and the guy still did not crash his plane. Thanks for you input...even better would be posting more photos of each step on how you think it should be done. Capt,n