GPM is that Procharged power? Did I hear u went to an M5? When u kill the XR's, is it from long runs or just hard acceleration?.. How fast are u running when you pull the trigger, or are you going one click at a time and still breaking them.. ??
And what is breaking the gears giving off metal?? or other parts too?

D*ck

Dick,gpm's lower gears fail in less then 5 hours,treated gears made no difference. My personal opinion is the substrate of the gears is giving up,I no longer believe cryoing,polishing or coatings of any kind will make a difference in his particular application,with 1400 plus hp combined with some of the tallest props available the only answer will be a set of lower gears made from a different alloy/composition. I'm still finishing some testing with some different gear coatings in my own boat at 1050 hp and I am working on having custom gear sets made to experiment with in the spring. Even though the hp levels we are running with these bravos seems like it should just cause instant destruction for the most part once all the shafts have been replaced with billet parts and all the other hd upgrades have been done the failure point ends up being the lower gears. If we can get some lower gears that will live then we can go back to breaking everything else again ,Smitty

Smitty,
You are probably right. Without looking at the whole picture, it is hard to tell. I was just trying to get a look at that picture.
People have been chasing the weakest link for years!

Mr G, yes I do run the 5, it doesn't seem to matter much what I do the gears are usually junk in 5 to 10 hours. Unless I make a couple of hard runs, 2 or 3 will eat them up. I've eased it up into the 120s or so and hit it, one time I hit it at 140 and snapped the vert shaft. For the most part it's always the lower gears.
I don't expect the drive to live, I'm not complaining about it, I know it's my fault they're breaking.

You are going crazy fast.. that is for sure!! My main experience with higher hp setups, was the 25' H2x that went 109 at LOTO two years back. Local guy that started with 700hp, then 970hp, then 1170hp, then 1400hp. At the lower levels we could get 60hrs out of a set of gears, upper or lower. Now he drove the boat like he hated it.. He only whacked the throttle if someone was next to him. ( I was told, by others, that happened more often than not.) They would race up to 100 or so and then let off.
When he went to 1400hp, I told him 5min max and it would break. He ran it three weekends and said he made at least, 15 hard passes. I tore the drive down and it looked very good inside. The shafts were original, so I was impressed. The gears looked like they were just broken in I had made some changes to that drive, but not sure if they added to the life.
I realize you are putting more load to the drive, but there may be some things that might help.. Like you say, if we could get to some degree of acceptable life, that would be a good thing!! Give me a call and we can talk..

D*ck

[QUOTE=GPM;2306732]Unless I make a couple of hard runs, 2 or 3 will eat them up. I've eased it up into the 120s or so and hit it, one time I hit it at 140 and snapped the vert shaft. For the most part it's always the lower gears.
IQUOTE]

Slightiy off topic, but how does the boat handle a drive letting go @ 140?

It just coasted to a stop, I'm sure it would have been worse if it would have locked up. Bad part, my rev limiter didn't work, the engine went wild and bent a bunch of valves.

GPM,
Nice talking to you yesterday!! Got me to thinking, now I will try to apply my thoughts and see what happens.
I think if I were you.. I would be shopping for an NXT, but it may be whole new set of issues..

D*ck

I think a trick setup would be a BMax upper with a modified lower that had 4 gears, 2 pinion and 2 drive gears.... Like a #6 lower....

Gonna be hard to make the lowers stronger without making the gears bigger or adding more of them...

I was wondering about a 5 for the bottom, B Max upper.