*THE HULL TRUTH is the world's largest FREE network for the discussion of Boating & Fishing. Whether you're researching a new boat, or are a seasoned Captain, you'll find The Hull Truth Boating & Fishing Message Forum contains a wealth of information from Boaters and Sportfishermen around the world.
Welcome to the updated THT!
If you are having trouble signing in, please email feedback@thehulltruth.com with your username and we will help you. We thank you for your patience as we help you access the new site!
you obviously haven't taken your own advise. Apparently you have not read any references posted here. Your rebuttal is worthless, you have no supporting data.
"The power exerted by a rotating object is the torque it exerts multiplied by
the speed at which it rotates. In standard English units, this would be
foot-pounds multiplied by radians/second. It is a special property of
radians that allows this product to be foot-pounds/second: a radian is a
distance around an arc divided by the length of the radius (feet per foot).
We start with 1 horsepower. We want to get to (foot-pounds)x(rpm).
1 hp = 550 ft-lbs/sec = 550 (ft-lbs)x(rad/sec)
1 rad/sec = 60 rad/min
= 33,000 (ft-lbs)x(rad/min)
1 revolution=2(pi)radians
1 rpm = 2(pi) rad/min
1 hp = 5252 (ft-lbs)(rpm)
"
Now that you have located these formulas, maybe if you study them harder you will understand how stupid this comment was:
"For instance, an electric screwdriver has a very large gear reduction because it needs lots of torque to turn screws, bu*t the motor only produces a small amount of torque at a high speed. With a gear reduction, the output speed can be reduced while the torque is increased. "
"Most modern gearboxes are used to increase torque while reducing the speed of a prime mover output shaft (e.g. a motor drive shaft). This means that the output shaft of a gearbox will rotate at slower rate than the input shaft, and this reduction in speed will produce a mechanical advantage, causing an increase in torque. A gearbox can be setup to do the opposite and provide an increase in shaft speed with a reduction of torque. Some of the simplest gearboxes merely change the physical direction in which power is transmitted.
Many typical automobile transmissions include the ability to select one of several different gear ratios. In this case, most of the gear ratios (often simply called "gears") are used to slow down the output speed of the engine and increase torque. However, the highest gears may be "overdrive" types that increase the output speed."
Once again, you rebuttal is worthless. I am starting to believe you have not made it through high school.
"For instance, an electric screwdriver has a very large gear reduction because it needs lots of torque to turn screws, bu*t the motor only produces a small amount of torque at a high speed. With a gear reduction, the output speed can be reduced while the torque is increased. "
"Most modern gearboxes are used to increase torque while reducing the speed of a prime mover output shaft (e.g. a motor drive shaft). This means that the output shaft of a gearbox will rotate at slower rate than the input shaft, and this reduction in speed will produce a mechanical advantage, causing an increase in torque. A gearbox can be setup to do the opposite and provide an increase in shaft speed with a reduction of torque. Some of the simplest gearboxes merely change the physical direction in which power is transmitted.
Many typical automobile transmissions include the ability to select one of several different gear ratios. In this case, most of the gear ratios (often simply called "gears") are used to slow down the output speed of the engine and increase torque. However, the highest gears may be "overdrive" types that increase the output speed."
Once again, you rebuttal is worthless. I am starting to believe you have not made it through high school.
Keep posting links you don't understand-it's really entertaining.
where you high when you wrote this ? torque is a measurement of applied force. Please explain how you can have torque without movement
again , what the hell are you talking about. You give me a breaker bar 3 foot long on a lug nut, i'll move the f*ck out of that car.
no HP is the overall measuremeant of torque over a given speed (rpm)
The funniest part about you is how you combine arrogance, confusion, and anger. You start out by telling people they need to learn more about engine dynamics, and then when someone points out that you don't know what you are talking about, you freak out.
I don't want to explain this stuff to you, since that would be a waste of time. But think about this:an electric motor has infinite torque at 0 rpm. That probably blows your mind.
The funniest part about you is how you combine arrogance, confusion, and anger. You start out by telling people they need to learn more about engine dynamics, and then when someone points out that you don't know what you are talking about, you freak out.
I don't want to explain this stuff to you, since that would be a waste of time. But think about this:an electric motor has infinite torque at 0 rpm. That probably blows your mind.
ok, now that your the resident scholar. An electric motor achieves its MAXIMUM tq at 0 rpm not infinite. Now the op is on an internal combustion engine, explain to me an an internal combustion engine runs @ 0 rpm ?
Where is the Yamaha competitive torque curve that shows how much more torque it has vs the Verados, Etecs, suzukis, etc.. Are there any independent tests done to prove? IMPO i'd rather have the lightest possible outboard with the most available HP.
Let's look at the lug nut thing. If you "torque" the lug nut to 40 ft.lbs., but DON'T move anything, you've done NO work. All you've done is applied a force. No movement..displacement..no work!
Engine torque is measured with movement, thus work. Once you're done twisting the lug nut to the desired "torque", all you're doing is applying force to the nut, which isn't moving...no more work.
Let's look at the lug nut thing. If you "torque" the lug nut to 40 ft.lbs., but DON'T move anything, you've done NO work. All you've done is applied a force. No movement..displacement..no work!
Engine torque is measured with movement, thus work. Once you're done twisting the lug nut to the desired "torque", all you're doing is applying force to the nut, which isn't moving...no more work.
Work = D (distance moved) x F (force applied)
although this means nothing, as you can see how he read into my earliest post. How can an engine(internal combustion not electric motor<--- i realized i now have to be very specific as you can not read into things) make torque without movement ?
Start the engine in your vehicle, stand on the brakes, put it in gear (assuming an automatic trans), and give it some gas.The engine will rev to a certain point, straining against the brakes.
It may not move but it sure is making torque. Same as trying to free a stuck nut/bolt by pulling on the wrench. It may not come loose but you are still applying torque to it.
Start the engine in your vehicle, stand on the brakes, put it in gear (assuming an automatic trans), and give it some gas.The engine will rev to a certain point, straining against the brakes.
It may not move but it sure is making torque. Same as trying to free a stuck nut/bolt by pulling on the wrench. It may not come loose but you are still applying torque to it.
Speed, without seeing torque plotted out, I'd guess the 4 strokes have a much broader torque curve. Many use variable valve timing and adjustable intake runners. 2 strokes are historically pretty peaky.
Typically E-TEC and Optimax produce a much wider flatter torque curve than 4 strokes. Direct injection helps as does having a fair bit of displacement.
Peaky 2 strokes are generally found where small displacement is being used to develop a fair bit of horsepower. eg 250cc motorbike that still goes like the clappers. You can get a lot of horsepower out of 250cc two stroke but it won't make a lot of low down torque
Typically E-TEC and Optimax produce a much wider flatter torque curve than 4 strokes. Direct injection helps as does having a fair bit of displacement.
Peaky 2 strokes are generally found where small displacement is being used to develop a fair bit of horsepower. eg 250cc motorbike that still goes like the clappers. You can get a lot of horsepower out of 250cc two stroke but it won't make a lot of low down torque
the same applies to the wankle rotary engine, and gear reduction is used to get the most efficiency out of the narrow power band at high rpms.
Hmmm..good analogy 396, but not in the direction you want. The ENGINE is doing work, creating heat, by allowing the torque (sic) converter to slip, while it's pumping fluid. This in turn applies a FORCE to the driveshaft, but performs no work or heat.
NOW, if it were a stick shift, the engine would immediately die, with the force applied to the driveshaft. Again, no work, no heat, only FORCE.
Technically, there is no torque without movement..force, yes, torque, no.
Last edited by billinstuart; 11-16-2009 at 01:40 PM.
Reason: spealing
Don't confuse Torque with work (work meaning horsepower). A couple of definitions:
Mechanics: something that produces or tends to produce torsion or rotation; the moment of a force or system of forces tending to cause rotation.
Machinery: the measured ability of a rotating element, as of a gear or shaft, to overcome turning resistance.
Horsepower is a unit of measure dating back to when horses were used for getting work done. As pointed out HP is nothing but a calculation; torque X RPM.
Very basically, torque is what gets the load moving. Calculated HP is what keeps it moving.
I see where you're going Bill, but I'll have to disagree (until l educate myself otherwise). As I understand it torque isn't a measure of work, it's a measure of force which in turn can/may result in work.
Remember, an electric motor makes it's max torque at 0 RPM, resulting in no work being done, agreed? So even though no work is being done it is still making torque.
Here's yet another quote I found: "Torque is the force that produces rotation. It causes an object to rotate. Torque consist of a force acting on distance. Torque, like work, is measured is pound-feet (lb-ft). However, torque, unlike work, may exist even though no movement occurs."
Dang it, I'm going to have to dig out some books. Watching you guys bat this around is now making me think about what I thought I already knew!
Boat # 1 is a 26' deep V pilothouse with a 200 hp, volvo diesel and duoprop.
Boat # 2 is a 26' deep V cuddy with a pair of 250hp outboards.
Tuna are at 60 miles due west and a wide open bite.
We are leaving at 3am and heading into a 25 knot breeze with 5' wind chop along with a 9'
swell..
Skipper in Boat # 1 sets his course, once past the bar, then sets his throttle at a 19 knot cruise and settles in for a 3 hr run.
Taps the wheel once in a while, watching the charts and having some coffee, bs with the hands.
Skipper in Boat#2 Sets his course, once past the bar, gets her up on a plane at 22/25 knots.
Speed starts climbing after each swell and pretty soon we are getting some air off the swells.
Back off the throttle and let her settle down.
After trimming the bow down a bit, we try again. Throttles on then off, over and over. Just will not maintain an even heading.
Narrow power band with climbing up and down hills is a pain..All hands are beat up, skipper gets no coffee.
Kinda like the young Bull and the cows.
Torque is like the old Bull..
Don't confuse Torque with work (work meaning horsepower). A couple of definitions:
Mechanics: something that produces or tends to produce torsion or rotation; the moment of a force or system of forces tending to cause rotation.
Machinery: the measured ability of a rotating element, as of a gear or shaft, to overcome turning resistance.
Horsepower is a unit of measure dating back to when horses were used for getting work done. As pointed out HP is nothing but a calculation; torque X RPM.
Very basically, torque is what gets the load moving. Calculated HP is what keeps it moving.
correct, the crankshaft is still rotating which at the crankshaft is still producing torque. Now apply an equal opposite force using an engine brake(no fluid couplers like a TQ converter), will the crankshaft still be turning ?
Old Bull 
