Hard on the Drives???
02-12-2014 | 10:27 AM
#41
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From: Somewhere in Ohio
is this hard on the drive??? 
full throttle to straight full throttle reverse....
http://www.youtube.com/watch?v=68AOltMu768
full throttle to straight full throttle reverse....http://www.youtube.com/watch?v=68AOltMu768
02-12-2014 | 10:41 AM
#42
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From: Michigan
I agree that there have been some issues with certain XRs. But, people far more knowledgeable than me have highly recommended the X drive.
02-12-2014 | 10:42 AM
#43
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From: Clarkston, Michigan
While I see absolutely no good reason to do full throttle starts, what do you think they do during powerboat testing and performance reports? I'd probably rather buy a 33 Fountain with 496's that had some full throttle starts on a small lake or river, over the 33 with 496's that ran it offshore in big water like great lakes or the ocean getting it airborne every weekend.
Many times drives break not because of HP. Prop pitch, boat weight, prop style, x dimension, etc. Perfect example is the 42 Fountains with the dry sump 6 drives coupled to the 700SCI. The 700SCI isn't busting the drive. Its the high propshaft height, 6 blade props, high pitch, rough water etc. Then there are guys with dry sump 6's running a lot more hp through them on a 41 apache with no issues.
I can tell you from a friend who's developed a product, that you will see on the market very soon, the engine isn't breaking the drives in most cases. When you have torque sensors hooked to your driveshaft measuring the torque readings live and logged into a laptop, on flat ass calm water, the most the drivetrain will see is whatever the engine produces. Get into any kind of chop/rough water, even at moderate speeds, and you'll find the torque spikes on the drivetrain to be in the thousands of ft lbs.
Think of it this way. You can take a bone stock mustang and floor it from redlight to redlight without wheel spin, and the trans,rear axles will most likely take it all day long. Now, dump that clutch and let those tires break loose, spinning and smoking until they bite, and see how long before you smoke a rear end or snap an axle. Happens all the time in the big truck world. You can have a big old Kenworth with a 600 cummins in it, loaded to 80k+ lbs, and boost it up with your foot to the floor all day getting up to speed or climbing a mountain. Get that truck off the pavement in some loose gravel or mud, and get some wheel spin going while your foots on the throttle. That's when the service truck has to come out to replace a busted axle or pinion gear.
Take a slab of concrete and you can park a semi truck on it and not crack it. Smack it hard enough with a 20 lb sledge hammer and watch it crack. Concrete is strong, but brittle. Much like gears and shafts.
Many times drives break not because of HP. Prop pitch, boat weight, prop style, x dimension, etc. Perfect example is the 42 Fountains with the dry sump 6 drives coupled to the 700SCI. The 700SCI isn't busting the drive. Its the high propshaft height, 6 blade props, high pitch, rough water etc. Then there are guys with dry sump 6's running a lot more hp through them on a 41 apache with no issues.
I can tell you from a friend who's developed a product, that you will see on the market very soon, the engine isn't breaking the drives in most cases. When you have torque sensors hooked to your driveshaft measuring the torque readings live and logged into a laptop, on flat ass calm water, the most the drivetrain will see is whatever the engine produces. Get into any kind of chop/rough water, even at moderate speeds, and you'll find the torque spikes on the drivetrain to be in the thousands of ft lbs.
Think of it this way. You can take a bone stock mustang and floor it from redlight to redlight without wheel spin, and the trans,rear axles will most likely take it all day long. Now, dump that clutch and let those tires break loose, spinning and smoking until they bite, and see how long before you smoke a rear end or snap an axle. Happens all the time in the big truck world. You can have a big old Kenworth with a 600 cummins in it, loaded to 80k+ lbs, and boost it up with your foot to the floor all day getting up to speed or climbing a mountain. Get that truck off the pavement in some loose gravel or mud, and get some wheel spin going while your foots on the throttle. That's when the service truck has to come out to replace a busted axle or pinion gear.
Take a slab of concrete and you can park a semi truck on it and not crack it. Smack it hard enough with a 20 lb sledge hammer and watch it crack. Concrete is strong, but brittle. Much like gears and shafts.
02-12-2014 | 10:46 AM
#44
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From: chicago
I'm sorry but your logic is flawed! Tires breaking loose and spinning takes the shock off a cars rear axles. Dumping the clutch with hot sticky slicks is when things break. Have you ever tried to break up a slab of concrete with a sledge? You cannot! It only chips. You must use a jack hammer.
Tires breaking loose takes the load off, however when they BITE again, is when $hit breaks.
https://www.youtube.com/watch?v=lKSs3I8v9tI
Last edited by MILD THUNDER; 02-12-2014 at 10:50 AM.
02-12-2014 | 10:59 AM
#45
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In the drag racing world a clean launch rarely breaks anything. It's when you start to slip or wheel hop. If you break at launch your not setup right. Regardless that's cars we are talking outdrives couple of extra angles to figure in. And anybody who ever has done construction will tell you a sledge will break concrete just can't swing it like a purse.
02-12-2014 | 11:12 AM
#46
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From: Michigan
I'm sorry but your logic is flawed! Tires breaking loose and spinning takes the shock off a cars rear axles. Dumping the clutch with hot sticky slicks is when things break. Have you ever tried to break up a slab of concrete with a sledge? You cannot! It only chips. You must use a jack hammer.
Now, dump that clutch and let those tires break loose, spinning and smoking until they bite, and see how long before you smoke a rear end or snap an axle.
IMO, a wide-open holeshot is nothing compared to a "missed throttle pull".
02-12-2014 | 11:18 AM
#47
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From: San Diego
somersfly by sh!t usually breaks when the wife is at shore and we are out having way too much fun 
As far as the drive deal. Surface drive causes vibration that causes wear and stress.. Usually a surface drive ( bravo) will pop when secreaming to get on plane because of vibration. Or that will make it weak and then it will brak when under power. You have to look at all that boat weight . bow lift stress etc is all riding on those thin little propshafts. Reguardless of weather or not having extra bikini's cuases the stuff to break or not does not concern me. Just the amount of fun that takes place during the event is what mastterrs ! back to this guy. he looks like he is having fun.. just needs to hook up the red cord and keep his had on the throttle.
As far as the drive deal. Surface drive causes vibration that causes wear and stress.. Usually a surface drive ( bravo) will pop when secreaming to get on plane because of vibration. Or that will make it weak and then it will brak when under power. You have to look at all that boat weight . bow lift stress etc is all riding on those thin little propshafts. Reguardless of weather or not having extra bikini's cuases the stuff to break or not does not concern me. Just the amount of fun that takes place during the event is what mastterrs ! back to this guy. he looks like he is having fun.. just needs to hook up the red cord and keep his had on the throttle.
02-12-2014 | 01:33 PM
#48
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From: Western N.Y.
I know on my big blocks there was only a 48 lb-ft difference between 3000rpm and max torque and only 13 lb difference between 3000 and full throttle 5500. My motors aren't stock but pretty mild compared to a lot of the motors on here so not sure how it applies.
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Straight bottoms and flat decks
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02-12-2014 | 01:55 PM
#49
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From: Clarkston, Michigan
I've tried breaking up concrete with a sledge and only made chips. It wouldn't crack no matter how hard I hit it. Now if it were already lifted then it may be easier to break up. Tires do not spin and then magically hook up. You either hook up or go up in smoke. Anyway, carry on. I thought we were talking about boat drives..
02-12-2014 | 09:00 PM
#50
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From: Brookfield Wi
I've tried breaking up concrete with a sledge and only made chips. It wouldn't crack no matter how hard I hit it. Now if it were already lifted then it may be easier to break up. Tires do not spin and then magically hook up. You either hook up or go up in smoke. Anyway, carry on. I thought we were talking about boat drives..
http://www.youtube.com/watch?v=HOmXCbVIU_c
