Quote:
Originally Posted by MTron
400 lb/ft at 8000 rpm ->6th gear -> 14 285 rpm and 224 lb/ft at the drive-shaft
400 lb/ft at 6000 rpm ->6th gear -> 10 714 rpm and 224 lb/ft at the drive shaft
as you can see the overdrive 6th gear of the transmission increased the rpm of the drive shaft but decreased the torque, but the higher revving engine has more rpm's in the driveshaft, so for the same speed of the drive shaft, we can change the ratio a bit and the higher revving engine will have more torque in the drive shaft
400lb/ft at 8000 rpm, with a .746:1 transmission ratio, will give us 10 714 rpm (same as the 6k rpm engine above) but it now has 298.4 lb/ft available
all this means, at the same speed, the higher revving engine will put more power to the wheels then the lower revving engine, but all at the cost of having a very narrow power band
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Out of all that, I think this will illustrate my point the best. Modifying the example you provided, using a low torque/high rev engine making 300 ft llbs.
300 lb/ft at 8000 rpm ->6th gear -> 14 285 rpm and 168 lb/ft at the drive-shaft
400 lb/ft at 6000 rpm ->6th gear -> 10 714 rpm and 224 lb/ft at the drive shaft
Both engines there are making 457 hp in that case but the high torque engine . . . makes more torque. if the final drive ratio is 3:1 for the HT (high torque) and 4:1 for the HR, you get:
HR ->14285 rpm/168 ft lbs -> 3571 rpm 672 ft lbs
HT ->10714 rpm/224 ft lbs -> 3571 rpm 672 ft lbs
They give the same numbers because they have the same power. So with proper gearing, the wheels won't know the differance. So whats the advantage of making a screamer vs making a stump puller, given all of the negatives associated with high revs?