800hp through an xr drive
03-26-2015, 06:39 AM
#41
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03-26-2015, 08:41 AM
#42
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I have to agree with the temp/oil theory on Bravos. We run Bravo X's w/ Bravo 2 lowers with bone stock 502 MPI's on our Parasail boats. Gear oil is changed every 100 hrs w/ Merc synthetic lube ( about every 2 weeks from now till end of August ). Our boats run about 2500 to 3500rpm tops during operation and the only time the prop leaves the water is when it comes out for service . We dont have many issues with lowers ( Bravo 2 has the big shaft ).
Before going to 1000gpm dedicated drive showers ( basically commercial baitwell pumps with 1 1/4" hose outlets) , we would get approx 200hrs before they would start to howl with the standard tube style showers. Now we get about 350 to 400hrs before replacing. I know it sounds like a lot of hours , but I'm just pointing out the advantage of keeping the heat out of these things .
Before going to 1000gpm dedicated drive showers ( basically commercial baitwell pumps with 1 1/4" hose outlets) , we would get approx 200hrs before they would start to howl with the standard tube style showers. Now we get about 350 to 400hrs before replacing. I know it sounds like a lot of hours , but I'm just pointing out the advantage of keeping the heat out of these things .
03-26-2015, 08:51 AM
#43
IMO, the number 1 killer of drives, isn't the engine. Its coming out of the water. I'm not talking about jumping a cruiser wake every once and a while for a photo opportunity. Im talking about the guys who boat in rough water, or even "choppy" water if you will, where for 30 miles, his props have broke the surface 287 times, and the tachs, nor the human ear barely picked up.
03-26-2015, 09:05 AM
#44
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I equate the Bravo drive problem to back in the day when you would break GM rear ends at the track. No one expected the stock 10 bolt rear end to last when you built up big power and try to hook it up at the track. I don't remember anyone bad mouthing GM on the rear end. Instead, you swapped it out for a 12 bolt or better yet, a 9" Ford. My memories from hanging out with the local bracket racers back in the day were that the car was only as good as its weakest link. That meant starting at the back of the car and working your way forward. I rarely see that in the boating world. Everyone wants to start at the front and then either not fully realize the potential of what they built due to fear of failure or they throw good money after bad on parts that were never designed for the task. I guess I'm different in that if I'm going to modify my boat for more speed, I'm starting at the drive. In most cases that means the Bravo goes in the swap shop before the motor comes out to go to the builder. I get the frustration over the Bravo drive, but Merc only puts them behind 600 HP max. That is probably a mistake on their part but who is buying a 520/525/565/600 with a mandated NXT? They need an affordable bridge between the Bravo and the NXT or SSM VI. Just my .02. .
03-26-2015, 10:15 AM
#45
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iTrader: (1)
I equate the Bravo drive problem to back in the day when you would break GM rear ends at the track. No one expected the stock 10 bolt rear end to last when you built up big power and try to hook it up at the track. I don't remember anyone bad mouthing GM on the rear end. Instead, you swapped it out for a 12 bolt or better yet, a 9" Ford. My memories from hanging out with the local bracket racers back in the day were that the car was only as good as its weakest link. That meant starting at the back of the car and working your way forward. I rarely see that in the boating world. Everyone wants to start at the front and then either not fully realize the potential of what they built due to fear of failure or they throw good money after bad on parts that were never designed for the task. I guess I'm different in that if I'm going to modify my boat for more speed, I'm starting at the drive.
The other isue, is that people talk about 600hp today like it is nothing. Just doesn't sound as powerful as it really is. Does it ?
Put 600hp, with 600ft/lbs of torque in your stock M22 trans'd stock 12 Bolt rear Camaro with some good traction and let me know how it works out.
600ft/lbs breaks stuff. In fact, it breaks really strong stuff.
03-26-2015, 10:18 AM
#46
Platinum Member
Platinum Member
I have to agree with the temp/oil theory on Bravos. We run Bravo X's w/ Bravo 2 lowers with bone stock 502 MPI's on our Parasail boats. Gear oil is changed every 100 hrs w/ Merc synthetic lube ( about every 2 weeks from now till end of August ). Our boats run about 2500 to 3500rpm tops during operation and the only time the prop leaves the water is when it comes out for service . We dont have many issues with lowers ( Bravo 2 has the big shaft ).
Before going to 1000gpm dedicated drive showers ( basically commercial baitwell pumps with 1 1/4" hose outlets) , we would get approx 200hrs before they would start to howl with the standard tube style showers. Now we get about 350 to 400hrs before replacing. I know it sounds like a lot of hours , but I'm just pointing out the advantage of keeping the heat out of these things .
Before going to 1000gpm dedicated drive showers ( basically commercial baitwell pumps with 1 1/4" hose outlets) , we would get approx 200hrs before they would start to howl with the standard tube style showers. Now we get about 350 to 400hrs before replacing. I know it sounds like a lot of hours , but I'm just pointing out the advantage of keeping the heat out of these things .
I also believe that heat is a major factor in Bravo failures....but I can't prove it. The drive in a performance boat is mostly out of water at high RPM's for an extended length of time. Can you post a picture of your rigging?
03-26-2015, 12:07 PM
#47
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iTrader: (5)
I equate the Bravo drive problem to back in the day when you would break GM rear ends at the track. No one expected the stock 10 bolt rear end to last when you built up big power and try to hook it up at the track. I don't remember anyone bad mouthing GM on the rear end. Instead, you swapped it out for a 12 bolt or better yet, a 9" Ford. My memories from hanging out with the local bracket racers back in the day were that the car was only as good as its weakest link. That meant starting at the back of the car and working your way forward. I rarely see that in the boating world. Everyone wants to start at the front and then either not fully realize the potential of what they built due to fear of failure or they throw good money after bad on parts that were never designed for the task. I guess I'm different in that if I'm going to modify my boat for more speed, I'm starting at the drive. In most cases that means the Bravo goes in the swap shop before the motor comes out to go to the builder. I get the frustration over the Bravo drive, but Merc only puts them behind 600 HP max. That is probably a mistake on their part but who is buying a 520/525/565/600 with a mandated NXT? They need an affordable bridge between the Bravo and the NXT or SSM VI. Just my .02. .
03-26-2015, 02:59 PM
#49
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03-26-2015, 03:12 PM
#50
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Join Date: Jul 2012
Location: Central Square & Fishers Landing, 1000 Islands NY
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I will just throw my most likely useless two cents in here but I have a 1991 42 Fountain with the original '91 Bravos with 1:36 ratio on it with -2 Imco shorties. The boat most recently had triple 565-575hp HP500 triples in it. I have owned it for two years in this configuration, and I have known the three previous owners before me going way back to 1997. The boat has NEVER been a drive breaker, and the boat doesn't have drive showers on it. I don't beat on it but I don't baby it either. What I don't do is get in it and jam the sticks to the dashboard out of the hole and hope for the best. Granted, I run the boat in the 1000 Islands and it very rarely leaves the water. I am finishing up three brand new Bob Madera designed 548's that we hope churn out around 675hp @ 5800 rpms. As a precaution I am having the drives freshened with heavy duty shafts in the uppers and bigger shafts in the lowers. Just as a precaution. Myself and the previous two owners only run Redline HD gear oil in the drives and the magnets are spotless. My fingers are crossed.
