About 10-20%, Smitty

I'm not sure what the original poster expects from Konrad but the underlying question is why would these drives that are supposedly premium drives break numerous times in 120 hours at 9000 x 2 $ per rebuild every 45 hours or so, this guy has 750 hp, not 1200. I don't care how much money someone has, your talking 400$ a hour for every hour the boat runs for drive repairs, thats steep for ANYONES pocketbook! If these things break that easy the word needs to get out. So Konrad lowered the rating on them to 738 ft lbs at one point, you would still think that there would be somewhat of a safety margin before the drives will self destruct on a regular basis!

90% is probably poor throttling.

Maybe and combined with some big as 5 or 6 blades with low slip?

I can't believe nobody has asked these questions yet;

What broke on your drives, upper, lower, what is the mode of failure, did they both fail the same way?

From what i've read here we're not getting the entire picture. I've seen alot of drives over the years and usualy they start failing for a reason. I've seen bravos on big heavy boats with big power bravos stay alive for years with proper care and sensible driving. I've also seen light little boats (a Pantera I know comes to mind) with pretty pedestrian HP tear through drives like there's no tomorrow because the owner ran it on the pins all the time. You can break anything if you try or by not knowing how to operate it within it's design envelope.

Won't grinding the nose change the hydrodynamics of the original design? Not that it should affect internals at all, but it will affect how it pulls through the water?
Bought, sold, bought, sold, bought, sold? How old is this drive?

Was this a driveline failure, u-joint?

I hope not, the poster says it cost him 9000$ each plus s/h every time they touch them. I would really like to know whats breaking too!

I've broken a drivline on my Konrads and if it goes at or near WOT and on the long end it does some serious damage. Mine tore out the trany, gimbal housing and input shaft into the drive. I don't want to remember what that cost.... I will say it was no fault of the drive. I let a u-joint go and ran it hard knowing it needed replacing. Konrad was rather gentle on the parts that I needed. I've been through my drives and other than normal wear a tear I haven't noted anything that would point to impending catastrophic failure. All in all a great little drive. It's not indestructable but better than the alternatives in the kw/kg range and price.

Like I said earlier, we're not getting the entire picture. I'm not pointing fingers or taking sides but I have found when everything seems perfectly clear you are not in possession of all the facts.