Different gear ratio.... Lycoming 6 cylinders typicaly run a ratio of 1.3 :
1, so 700 hours is the most you should expect. Pretty good article on the
sacramento sky ranch site.
Jim


"Dave Butler" wrote in message
news:1145971786.778597@sj-nntpcache-5...
M wrote:
The life of vacuum
pumps on 6 cylinder engines is significantly shorter due to higher
rotation speed of the auxiliary shaft (?).

That's a new one on me. Why does the accessory drive spin faster on a 6?

Dave