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Quote:

Originally Posted by DORaymond (Post 2390676)

Would that be 1000/2000 horsepower & torque?

Nope. The only thing that occurs that isn't double is revolutions which is halved.

HP is work over time. HP can not be multiplied by gearing. Only torque.

HP = t * rpm/5252. So, 1000 hp 1000 ft lbs at 5000 rpm at 2:1.. means 2000 ft lbs and 1000 hp at 2500 rpm.

HP is the same through a whole system minus friction losses.

I didn't argue that above because Chris' point still stands, since the torque will kill the drive more so than HP.

I did learn some things in Kinematics of machinery :)

Yes, of course you're correct. Late afternoon brain-fade.

Quote:

Originally Posted by Chris Sunkin (Post 2390794)

Yes, of course you're correct. Late afternoon brain-fade.

I was hoping you were right! It would solve the world's energy problem!:D

Quote:

Originally Posted by sleeper_dave (Post 2390353)

Developement on CVT's has all but ceased by the auto makers. They just can't be made efficient or strong enough. Then there's the issue of driver perception. What good is a CVT if you have to program it to have artificial "gears" so that the driver doesn't think his tranny is slipping. CVTs are dead in the automotive world, and you don't want to think about inflicting that kind of extra pain on yourself by trying to put one in your boat. You think bravo's fail a lot... a CVT would last about as long as an alpha beind a 1075.

CVTs are fine for snowmobiles, but making them handle the abuse a car can put out, let alone a marine engine, is a big hurdle that will likely never be overcome, simply because of the lack of percieved benefit. Someone would have to come up with a new way of making a CVT, there is only so far you can go with belts and pullies when it comes to transmitting torque.

Don't tell NIssan that. JUst about all their cars are CVT autos now. ( Maxima, altima, etc..)

Quote:

Originally Posted by Joe92GT (Post 2390776)

Right on....................

I think a 2 speed tranny would be enough..

Quote:

Originally Posted by Chris Sunkin (Post 2390168)

Diesels would be the application that would see the least amount of benefit considering their exceptionally broad torque curve.

I would like to dispel the myth that diesels have a broad torque curve once and for all (yeah, like that's going to happen:D). If you look at a diesel's torque curve with the X-axis being RPM/Maximum RPM (which normalizes that axis for comparison to a gasoline engine), the diesel's torque curve is awful! It plummets below 0.5 RPM ratio, because the turbo boost is falling rapidly below that RPM. If you overlay the torque curve for a naturally aspirated gasoline engine, such as the 496, the gas engine appears almost flat from an RPM ratio of 0.2 and up. The curves are available from GM, Cummins, and others. Volvo has tried to overcome the diesel's poor torque curve by adding a mechanically driven roots blower IN ADDITION to the turbo. The blower is coupled to the engine with an electric clutch, similar to that used for an A/C compressor in your car, so it only engages at low engine speed. Unfortunately, I have not seen any published torque curves to see how well the system works.

Michael:ernaehrung004: