heres a question on this line what type of loads does a combustion engine experience when under load ie cylinder pressures. its got to be also pretty high at times.
i agree with andy about hydraulics being dangerous .
when i was young i had trouble unhooking a implement from a tractor and while trying to uncouple the hydraulics a tiny amount of oil was released under pressure caught me on the hand blew the stuff right under my skin and into the piece of meat between my thumb and forefinger like nothing . off to the doctor we go.