Can you get 98 ft/lbs of low end Torque on the CHEAP?
#11
09-16-2006, 10:22 AM
RE: Can you get 98 ft/lbs of low end Torque on the CHEAP?
If ya figure fuel intervals somewhere between 100 & 150+ miles, it had to be some of both up & down. I've expereinced this high milage "phenomenon" several times in the mountains.
I suppose it has to do with the fact that on the downhill sections, you're using very little fuel plus the fact that you're never really running fast (75 ~ 85mph) like highway speeds. THerefore there is much less wind resistence and lower RPM's...???....
I suppose it has to do with the fact that on the downhill sections, you're using very little fuel plus the fact that you're never really running fast (75 ~ 85mph) like highway speeds. THerefore there is much less wind resistence and lower RPM's...???....
#12
09-16-2006, 03:44 PM
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RE: Can you get 98 ft/lbs of low end Torque on the CHEAP?
42 - 44 mpg ain't too shabby with that much torque available. Reason I asked was I've seen several 100-100 bikes getting in the mid 30s for mpg. I get 50 - 52 on my '87 Evo Sloptail. Drops down to 46 - 48 running about 80 mph. Engine is stock except for an old round air cleaner, and 2-1/4 inch drags. Sure ain't got no torque like y'all's, but I do like the mileage.
#13
12-19-2006, 10:58 PM
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RE: Can you get 98 ft/lbs of low end Torque on the CHEAP?
just wondering why you didn't go with a set of SE-203's? what makes the andrews tw26a's better? i'm just trying to work up a build myself and was looking at the 203's because they were recommend by my builder.
#14
12-20-2006, 07:39 AM
RE: Frugal Man's 98 Low end Torque build
ORIGINAL: PipeDADDY
I agree with you. I am not out racing my ride at 5.5k RPM...so HP really won't make a difference to me. 95% of the time I am <4k RPM. Here is an interesting article.
The Case for Torque
First of all, from a driver's perspective, torque, to use the vernacular, RULES :-). Any given car, in any given gear, will accelerate at a rate that *exactly* matches its torque curve (allowing for increased air and rolling resistance as speeds climb). Another way of saying this is that a car will accelerate hardest at its torque peak in any given gear, and will not accelerate as hard below that peak, or above it. Torque is the only thing that a driver feels, and horsepower is just sort of an esoteric measurement in that context. 300 foot pounds of torque will accelerate you just as hard at 2000 rpm as it would if you were making that torque at 4000 rpm in the same gear, yet, per the formula, the horsepower would be *double* at 4000 rpm. Therefore, horsepower isn't particularly meaningful from a driver's perspective, and the two numbers only get friendly at 5252 rpm, where horsepower and torque always come out the same.
In contrast to a torque curve (and the matching pushback into your seat), horsepower rises rapidly with rpm, especially when torque values are also climbing. Horsepower will continue to climb, however, until well past the torque peak, and will continue to rise as engine speed climbs, until the torque curve really begins to plummet, faster than engine rpm is rising. However, as I said, horsepower has nothing to do with what a driver *feels*.
I agree with you. I am not out racing my ride at 5.5k RPM...so HP really won't make a difference to me. 95% of the time I am <4k RPM. Here is an interesting article.
The Case for Torque
First of all, from a driver's perspective, torque, to use the vernacular, RULES :-). Any given car, in any given gear, will accelerate at a rate that *exactly* matches its torque curve (allowing for increased air and rolling resistance as speeds climb). Another way of saying this is that a car will accelerate hardest at its torque peak in any given gear, and will not accelerate as hard below that peak, or above it. Torque is the only thing that a driver feels, and horsepower is just sort of an esoteric measurement in that context. 300 foot pounds of torque will accelerate you just as hard at 2000 rpm as it would if you were making that torque at 4000 rpm in the same gear, yet, per the formula, the horsepower would be *double* at 4000 rpm. Therefore, horsepower isn't particularly meaningful from a driver's perspective, and the two numbers only get friendly at 5252 rpm, where horsepower and torque always come out the same.
In contrast to a torque curve (and the matching pushback into your seat), horsepower rises rapidly with rpm, especially when torque values are also climbing. Horsepower will continue to climb, however, until well past the torque peak, and will continue to rise as engine speed climbs, until the torque curve really begins to plummet, faster than engine rpm is rising. However, as I said, horsepower has nothing to do with what a driver *feels*.
Scenario: Consider the engines below. Which one will make your car accelerate the quickest?
1st
Scania 16-liter V8, 620hp, 2200 lb/ft.
2nd
3-liter Fourmula 1 V10, 850hp(?) 250 lb/ft.
We assume that both engines weigh the same and have the same dimensions.
The Scania revs to 2'000rpm while the F1-engine revs to 20'000rpm. This means that the F1-engine can have 10 times shorter gears (20'000/2'000 = 10) and still reach the same speed in a specific gear. The gearbox works as a torque multiplier. This means that the torque of the F1-engine will be multiplied by 10 in the gearbox. So suddenly the F1 engine puts a maximum of 2500 lb/ft of torque to the wheels, while the Scania still only puts 2200 lb/ft. The F1 puts 13.6% more maximum torque to the wheels. The gearing is chosen so it is completely fair to both engines (both cars are able reach the same speeds in that gear). /end example
If you want your bike to accelerate the hardest at any given speed, say 60 mph for example, you want to choose a gear which puts you closest to your peak power. Similarly, if you used a continuously variable transmission (CVT) you would want it to work at peak power, not peak torque.
Your bike will never accelerate faster than your HP/weight-ratio allows, regardless of how much torque you have. But it sure is nice to have more low rpm grunt. :-)
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