i was thinking and i whated to know what would happen if i put a .21 engine in my Nitro Hammer. would it raddle the boat and make the hull crack? or not do anything at all? how much faster would it make it go? what about a .18?

i was looking at a .21 engine something like this:

http://img.photobucket.com/albums/v57/rg501/engine.jpg

^ would that fit? would i have to make a water cooling head or could i use the one that is already on my NH?