An engine that is running at 10.000 to 16.000 rpm , what do you expect to see at that speed? Just a blur. And when mounted 1/4 inch from a firewall, who is going to see in there? On a running engine i dont think it would be practicable. If my memory serves me right i think minflyer did a mobile view of an engine and posted it in here some time back . Maybe RcKen will remember it and dig it up for you .
Bill