making rotors higher compression...
04-30-2008, 09:40 PM
#21
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There's one thing commonly overlooked in the long bore/short stroke vs. small bore/long stroke conundrum.
It's somewhat common knowledge that a bigger bore means more potential valve area and therefore more power potential. Just geometrically there is more room for more valve. And a smaller bore means more efficient combustion because the combustion space is smaller and less flattened out.
But a longer stroke/smaller bore engine also works the ports harder. Theory is that the air has to move faster to get to the middle of the cylinder (middle being the "average") because it's always further away from the valves than in a big bore/short stroke combo.
It also means more port velocity, which is a Good Thing.
It's somewhat common knowledge that a bigger bore means more potential valve area and therefore more power potential. Just geometrically there is more room for more valve. And a smaller bore means more efficient combustion because the combustion space is smaller and less flattened out.
But a longer stroke/smaller bore engine also works the ports harder. Theory is that the air has to move faster to get to the middle of the cylinder (middle being the "average") because it's always further away from the valves than in a big bore/short stroke combo.
It also means more port velocity, which is a Good Thing.
05-01-2008, 12:59 PM
#22
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Originally Posted by Lynn E. Hanover' post='899295' date='Apr 25 2008, 07:57 AM
Since the world standard for measuring HP is the dyno, resolving avarage torque is a simple matter. The measured avarage torque times the RPM divided by the constant 5252 = HP. So, the torque gage tells you directly what the torque is.
HP is the torque (force) times the rate the force is being applied, so RPM says one revolution (to get the avarage) Per minute
(the rate) in increments of one minute. So one HP is 33,000 pounds lifted one foot in one minute.
Torque is a measurment of force.
Horse Power (actually a big draft horse) is a measurement of work. So there must be a time function. It is one minute. The "M" in RPM.
HP is the torque (force) times the rate the force is being applied, so RPM says one revolution (to get the avarage) Per minute
(the rate) in increments of one minute. So one HP is 33,000 pounds lifted one foot in one minute.
Torque is a measurment of force.
Horse Power (actually a big draft horse) is a measurement of work. So there must be a time function. It is one minute. The "M" in RPM.
Sorry, this is a few days old but I just wanted to correct this talk of units a bit to clear up some confusion. Torque is not a measure of force but of work. Pounds are measures of force, which is why we measure our weight (not our mass) when we hop on a scale and read out the number of pounds. Now work is force times distance, so moving one pound times one foot gives the work. You'll notice that the units multiply together like the vaules before them and you get foot-pounds. Thus torque is a measure of work since it shares units. The difference is that it acts in a circle, and the distance from the point of rotation is used for calculations.
Similarly horsepower is not a measurement of work but a measurement of power. Work has no sense of time. You can pull a 1 pound block 1 foot and it doesn't matter if it takes you a year or a minute, it's still just a foot pound of work. Clearly the rate at which something can do work is useful though and so we divide work by time for this value. The result is power, which can be horsepower for imperial units. In metric it's Watts, and I'm sure you've all seen european or japanese spec sheets and seen them boasting about horsepower numbers in kW or kilowatts.
Thus a truck engine has torque because it needs to pull large loads slowly, and a race engine has horsepower because it has less mass (less to pull) that it needs to go faster.
05-01-2008, 04:36 PM
#23
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Work requires motion. You can exert force and do no work. Most people are intimately familiar with this when trying to remove flywheel nuts with hand tools. You pull and strain and exert plenty of ft-lb but until you have motion you are doing no work.
05-01-2008, 07:58 PM
#24
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Originally Posted by Nateb123' post='899704' date='May 1 2008, 10:59 AM
Sorry, this is a few days old but I just wanted to correct this talk of units a bit to clear up some confusion. Torque is not a measure of force but of work. Pounds are measures of force, which is why we measure our weight (not our mass) when we hop on a scale and read out the number of pounds. Now work is force times distance, so moving one pound times one foot gives the work. You'll notice that the units multiply together like the vaules before them and you get foot-pounds. Thus torque is a measure of work since it shares units. The difference is that it acts in a circle, and the distance from the point of rotation is used for calculations.
Similarly horsepower is not a measurement of work but a measurement of power. Work has no sense of time. You can pull a 1 pound block 1 foot and it doesn't matter if it takes you a year or a minute, it's still just a foot pound of work. Clearly the rate at which something can do work is useful though and so we divide work by time for this value. The result is power, which can be horsepower for imperial units. In metric it's Watts, and I'm sure you've all seen european or japanese spec sheets and seen them boasting about horsepower numbers in kW or kilowatts.
Thus a truck engine has torque because it needs to pull large loads slowly, and a race engine has horsepower because it has less mass (less to pull) that it needs to go faster.
Similarly horsepower is not a measurement of work but a measurement of power. Work has no sense of time. You can pull a 1 pound block 1 foot and it doesn't matter if it takes you a year or a minute, it's still just a foot pound of work. Clearly the rate at which something can do work is useful though and so we divide work by time for this value. The result is power, which can be horsepower for imperial units. In metric it's Watts, and I'm sure you've all seen european or japanese spec sheets and seen them boasting about horsepower numbers in kW or kilowatts.
Thus a truck engine has torque because it needs to pull large loads slowly, and a race engine has horsepower because it has less mass (less to pull) that it needs to go faster.
Straingely, this was the explaination used in the early IMI textbook my son got the first day of school.
And it is completely wrong. Had a hell of a time convincing the instructor.
The Horsepower is definition is available by Googleing. By James watt. Designer of steam engines.
33,000 pounds lifted one foot in one minute. So there is a weight or force, (33,000) pounds, a distance (one foot) and a time (one minute)
If any of these are missing there is no HP to calculate. None exsists without all three elements. Period.
Torque is an twisting effort (or force) applied to a shaft . A twisting motion if you can see that better. There is no need for a motion figure. There is no need for a time factor . There is no need for a distance figure. If you clamp the square drive of your torque wrench in the jaws of a vice, and let the handle extend horizontally for all of eternity, the wrench will apply torque to the vice for all of eternity. No motion, no time limit.
The big nut on the crank is a good example. Trying to remove the nut and not succeeding while tiring is not work. Not until the torque applied results in a motion (distance) and a time factor has any work (HP)
been accomplished. Those are the rules as James wrote them down.
Lynn E. Hanover
05-01-2008, 11:41 PM
#25
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Join Date: Jan 2008
Location: Vancouver, BC
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Torque is an twisting effort (or force) applied to a shaft . A twisting motion if you can see that better. There is no need for a motion figure. There is no need for a time factor . There is no need for a distance figure. If you clamp the square drive of your torque wrench in the jaws of a vice, and let the handle extend horizontally for all of eternity, the wrench will apply torque to the vice for all of eternity. No motion, no time limit.
The big nut on the crank is a good example. Trying to remove the nut and not succeeding while tiring is not work. Not until the torque applied results in a motion (distance) and a time factor has any work (HP)
been accomplished. Those are the rules as James wrote them down.
Lynn E. Hanover
The big nut on the crank is a good example. Trying to remove the nut and not succeeding while tiring is not work. Not until the torque applied results in a motion (distance) and a time factor has any work (HP)
been accomplished. Those are the rules as James wrote them down.
Lynn E. Hanover
As for torque being work instead of force, heretic has already given the perfect explanation (except you exert pounds, not foot-pounds when doing no work). Force doesn't have to result in motion, something can simply hold fast and nothign moves. Go up to a wall and push on it, the force you experience back is of equal value and so you end up with nothing moving. It doesn't mean force isn't being exerted, only that work is not being done.
05-02-2008, 12:37 AM
#26
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[quote name='Nateb123' date='May 1 2008, 09:41 PM' post='899726']
You said:
Torque is not a measure of force but of work.
Similarly horsepower is not a measurement of work but a measurement of power. Work has no sense of time. You can pull a 1 pound block 1 foot and it doesn't matter if it takes you a year or a minute, it's still just a foot pound of work.
Also, I never said horsepower can be calculated without a measure of time, force and distance. Not sure what that's all about...
Allow me to continue:
Torque is a measurement of force in Newton Meters or Foot Pounds. It is not a measurement of work.
Horsepower is a measurement of work. It does require a time element.
If I have not been clear enough to get the basics across, I will keep at it for a while longer. But I am old, and I am getting tired.
Lynn E. Hanover
NA 12A GT-3 95 RX-7
250 HP at 9,400 RPM
You said:
Torque is not a measure of force but of work.
Similarly horsepower is not a measurement of work but a measurement of power. Work has no sense of time. You can pull a 1 pound block 1 foot and it doesn't matter if it takes you a year or a minute, it's still just a foot pound of work.
Also, I never said horsepower can be calculated without a measure of time, force and distance. Not sure what that's all about...
Allow me to continue:
Torque is a measurement of force in Newton Meters or Foot Pounds. It is not a measurement of work.
Horsepower is a measurement of work. It does require a time element.
If I have not been clear enough to get the basics across, I will keep at it for a while longer. But I am old, and I am getting tired.
Lynn E. Hanover
NA 12A GT-3 95 RX-7
250 HP at 9,400 RPM
05-02-2008, 12:57 PM
#27
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Location: Vancouver, BC
Posts: 143
Originally Posted by Lynn E. Hanover' post='899727' date='May 1 2008, 10:37 PM
Allow me to continue:
Torque is a measurement of force in Newton Meters or Foot Pounds. It is not a measurement of work.
Horsepower is a measurement of work. It does require a time element.
If I have not been clear enough to get the basics across, I will keep at it for a while longer. But I am old, and I am getting tired.
Torque is a measurement of force in Newton Meters or Foot Pounds. It is not a measurement of work.
Horsepower is a measurement of work. It does require a time element.
If I have not been clear enough to get the basics across, I will keep at it for a while longer. But I am old, and I am getting tired.
Excuse my use of metric, but I'm Canadian so it will make things easier for me.
Mass is measured in kilograms. Force is mass times acceleration and if you check the units you have that 1 newton=1kg*1m/s^2 (seconds squared). Now force is Newtons. Therefore torque can not be a measurement of force because it doesn't have the same units. Torque is in Newton-meters, force times distance. Clearly we need a definition of a quantity that is defined by the distance upon which and force is acting and it's called work. You clearly get the difference between horspower and torque so I won't bother with that definition.
However, I'm curious why you've decided that textbooks are wrong. I'm not saying everything that's been written down is right but how can you say that everyone else is misinterpreting the basics of units they're been using for a century? If we were removing the pounds from foot-pounds when referring to force, don't you think the units would clearly illustrate that? F=ma would not be a valid equation then, we'd be missing a factor for distance. Unless you're going to argue that one of Newton's laws is wrong, this should set things straight.
Now, my argument checks out in pure, rigid math. You've just said "You're wrong. Here's the correct definitions that everyone should be using", but saying I'm wrong and supplying your answer doesn't make it right. There needs to be a logical argument; a "why" behind it which your point is lacking. I'm not going to take your word on it and just have blind faith just as no one is going to take my word. I've done you the courtesy of spelling out my argument piece by piece, and patiently at that. Couldn't you do me the same courtesy?
05-02-2008, 01:33 PM
#28
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Originally Posted by Nateb123' post='899750' date='May 2 2008, 10:57 AM
Excuse my use of metric, but I'm Canadian so it will make things easier for me.
Mass is measured in kilograms. Force is mass times acceleration and if you check the units you have that 1 newton=1kg*1m/s^2 (seconds squared). Now force is Newtons. Therefore torque can not be a measurement of force because it doesn't have the same units. Torque is in Newton-meters, force times distance. Clearly we need a definition of a quantity that is defined by the distance upon which and force is acting and it's called work. You clearly get the difference between horspower and torque so I won't bother with that definition.
However, I'm curious why you've decided that textbooks are wrong. I'm not saying everything that's been written down is right but how can you say that everyone else is misinterpreting the basics of units they're been using for a century? If we were removing the pounds from foot-pounds when referring to force, don't you think the units would clearly illustrate that? F=ma would not be a valid equation then, we'd be missing a factor for distance. Unless you're going to argue that one of Newton's laws is wrong, this should set things straight.
Now, my argument checks out in pure, rigid math. You've just said "You're wrong. Here's the correct definitions that everyone should be using", but saying I'm wrong and supplying your answer doesn't make it right. There needs to be a logical argument; a "why" behind it which your point is lacking. I'm not going to take your word on it and just have blind faith just as no one is going to take my word. I've done you the courtesy of spelling out my argument piece by piece, and patiently at that. Couldn't you do me the same courtesy?
Mass is measured in kilograms. Force is mass times acceleration and if you check the units you have that 1 newton=1kg*1m/s^2 (seconds squared). Now force is Newtons. Therefore torque can not be a measurement of force because it doesn't have the same units. Torque is in Newton-meters, force times distance. Clearly we need a definition of a quantity that is defined by the distance upon which and force is acting and it's called work. You clearly get the difference between horspower and torque so I won't bother with that definition.
However, I'm curious why you've decided that textbooks are wrong. I'm not saying everything that's been written down is right but how can you say that everyone else is misinterpreting the basics of units they're been using for a century? If we were removing the pounds from foot-pounds when referring to force, don't you think the units would clearly illustrate that? F=ma would not be a valid equation then, we'd be missing a factor for distance. Unless you're going to argue that one of Newton's laws is wrong, this should set things straight.
Now, my argument checks out in pure, rigid math. You've just said "You're wrong. Here's the correct definitions that everyone should be using", but saying I'm wrong and supplying your answer doesn't make it right. There needs to be a logical argument; a "why" behind it which your point is lacking. I'm not going to take your word on it and just have blind faith just as no one is going to take my word. I've done you the courtesy of spelling out my argument piece by piece, and patiently at that. Couldn't you do me the same courtesy?
All I learned about this came from the instruction book for my Stuska Dyno. This collection is in line with my thinking.
http://www.vettenet.org/torquehp.html
Lynn E. Hanover
05-03-2008, 12:41 PM
#29
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Join Date: Jan 2008
Location: Vancouver, BC
Posts: 143
Originally Posted by Lynn E. Hanover' post='899754' date='May 2 2008, 11:33 AM
All I learned about this came from the instruction book for my Stuska Dyno. This collection is in line with my thinking.
http://www.vettenet.org/torquehp.html
Lynn E. Hanover
http://www.vettenet.org/torquehp.html
Lynn E. Hanover
Well I think I've found the problem here: unclear language. It was used on that website as well. Torque for some reason is used to describe a force as well as the work done by that force and as a result, foot-pounds and pounds end up being confused when it comes to the units of torque. Anyways, all that can be said has been, anything more would just be an argument about who is right rather than what is true.
