Where Torque Comes From
08-13-2003, 08:20 AM
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Where Torque Comes From
Aight. i'ma try something new (at least to me). Its a project to find out where torque comes from. I want to get a few opinions, lots of factual info, and some theories. I'd like to first exclude one thing: i'm only talking about the torque the engine makes at the flywheel not at the wheels, thats another whole diccussion. Lets first start off on how an engine makes power. Check out http://auto.howstuffworks.com/engine1.htm and http://science.howstuffworks.com/fpte3.htm first. Then lets start out by exactly defining torque. Now where can we get more, what makes it, and of course where does it come from?
We should be able to get some interesting things said. If you want to add something helpful please do if you just want to flame how stupid this then start a new post about it somewhere else please. Let's start.
We should be able to get some interesting things said. If you want to add something helpful please do if you just want to flame how stupid this then start a new post about it somewhere else please. Let's start.
08-13-2003, 09:57 AM
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Re: Where Torque Comes From (nightryder21)
it's more like where does horsepower come from...
here is an article i have posted many a time. read up, no cliff notes.
The topics of horsepower and torque can be confusing. We use these yardsticks to compare engines but what do they really mean, how are they related and which one is more important? An old saying is "torque wins races, horsepower sells cars". It implies the uninformed public is incorrectly focused on horsepower. Is that so?
In fact horsepower and torque are entirely different things and are measured using different units.
Torque - Torque is a measure of twisting force, pure and simple. Torque includes no concept of motion or time. This is easily understood by anyone who has used a torque wrench. A torque wrench can measure twisting force on a bolt that is stationary or turning. In the US torque is normally expressed in foot pounds.
Torque is created any time opposing forces are applied at different points along a lever arm. Imagine a weightless one foot long lever arm connected at one end to a stationary pivot point. If we apply a one pound force at the other end of that lever arm a one foot pound twisting force will be exerted (one foot pound of torque). If we apply a two pound force then a two foot pound twisting force will be exerted.
Engines exert torque at the crankshaft. That torque is coupled through the transmission, driveline and ultimately to the drive axle. The twisting force at the drive axle is converted to a linear force where the tire tread meets the road surface. The linear force is measured in pounds and pushes the car forward.
We can easily calculate the linear force that accelerates the car knowing only the torque at the drive axle and the diameter of the tires.
Linear force = Axle Torque / Tire Diameter / 2
The torque exerted by the engine varies with rpm and is typically expressed as a curve. The curve is the collection of instantaneous torque measurements at each rpm point.
Neglecting driveline losses, the axle torque and linear force that pushes the car are directly proportional to the crankshaft torque for a given gear. That means that, for a given gear and neglecting air resistance, the car will always accelerate at the same rate whenever the engine is producing a given torque. It doesn't matter what RPM the engine is turning or the speed of the vehicle. A perfectly flat torque curve would allow the car to accelerate the same at any RPM.
In the real world torque curves are not flat, they build to peak and then taper off at high RPM. A car will accelerate hardest in a given gear when the engine is operating at its torque peak.
Notice that we can figure out how hard the car is accelerating and horsepower doesn't even enter into the discussion.
Horsepower - Horsepower is a measure of the rate at which work can be performed. Motion and time are integral to horsepower which is typically expressed as foot pounds per minute in the US.
In this case work has nothing to do with your boss. Work means moving an object in opposition to a force (that may remind some of their boss). Raising one pound a distance of one foot is one foot pound of work. Raising one pound a distance of two feet is two foot pounds of work.
Horsepower combines the concept of work with time. In the 1700s James Watt of steam engine fame took some measurements and concluded that an average horse could lift a 550 pound weight one foot in one second. Watt defined one horsepower as 550 foot pounds per second or 33,000 foot pounds per minute.
We can show a direct relationship between torque and horsepower. Remember our one foot lever arm with the pivot at one end and one pound force at the other? If it rotates about the pivot one full revolution in one minute it will move that one pound 2*pi*r or 6.28 feet per minute (think about a point on a tire tread rotating about its axle). If it rotates at 5252 RPM it will move that one pound 6.28 * 5252 or 33,000 feet per minute, exactly one horsepower. Hence the relationship between horsepower and torque is defined as follows:
Horsepower = torque * RPM / 5252
This is a linear relationship and says that horsepower will rise in lockstep with RPM and torque. The horsepower produced by an engine varies with rpm and is typically expressed as a curve. The curve is simply the collection of instantaneous horsepower calculations at each rpm point.
To review we know that a) axle torque converted to linear force accelerates the car b) for a given gear the acceleration will be greatest at the engine torque peak and has nothing to do with RPM or speed c) horsepower is a calculated function of torque and RPM.
So horsepower doesn't matter, right? Wrong! Read on.
Torque multiplication - The transmission is a torque multiplier. Reduction gears are employed to make the drive shaft rotate at a slower RPM than the crank shaft (ignoring overdrive). These reduction gears cause a similar increase in the drive shaft torque.
As an example a hypothetical two-speed transmission might have a first gear with a 2:1 reduction gears and a second gear with 1:1 gears. Let's connect that transmission to a an engine that can produce 100 foot pounds of torque at the crank shaft throughout the RPM range.
The 1:1 second gear rotates the drive shaft at the same speed as the crankshaft and it will exert exactly the same 100 foot pounds of torque (neglecting frictional losses). However the 2:1 first gear rotates the drive shaft at half the speed of the crankshaft but it will exert 200 foot lbs of torque, twice the torque of the crank shaft! That means first gear will accelerate the car twice as hard as second gear.
Therein lies the key to why we care about horsepower. Through reduction gears maximum drive axle torque for a given vehicle speed is generated when the engine is operating at its horsepower peak and not its torque peak (they are rarely the same).
As an example recall our car with two speeds, flat torque curve, 100 foot pound engine. Imagine it has a 1:1 final drive ratio that propels the car at 107 mph (makes the math simple) at 1500 RPM in second gear using 24 inch diameter tires. We can also drive the car 107 mph at 3000 RPM in first gear. The engine is producing 100 foot pounds of torque in both cases. Which one accelerates the car faster?
The answer of course is first gear.
As a result of torque multiplication a car will accelerate fastest at any given MPH when a gear is selected that puts the engine at its horsepower peak and not its torque peak. This is one reason why small high-revving engines can often beat large low-revving engines. Despite a lower crankshaft torque, the high-revving engine can deliver greater drive axle torque through torque multiplication.
So there it is, torque and horsepower. It seems that horsepower is good for selling cars AND winning races.
here is an article i have posted many a time. read up, no cliff notes.
The topics of horsepower and torque can be confusing. We use these yardsticks to compare engines but what do they really mean, how are they related and which one is more important? An old saying is "torque wins races, horsepower sells cars". It implies the uninformed public is incorrectly focused on horsepower. Is that so?
In fact horsepower and torque are entirely different things and are measured using different units.
Torque - Torque is a measure of twisting force, pure and simple. Torque includes no concept of motion or time. This is easily understood by anyone who has used a torque wrench. A torque wrench can measure twisting force on a bolt that is stationary or turning. In the US torque is normally expressed in foot pounds.
Torque is created any time opposing forces are applied at different points along a lever arm. Imagine a weightless one foot long lever arm connected at one end to a stationary pivot point. If we apply a one pound force at the other end of that lever arm a one foot pound twisting force will be exerted (one foot pound of torque). If we apply a two pound force then a two foot pound twisting force will be exerted.
Engines exert torque at the crankshaft. That torque is coupled through the transmission, driveline and ultimately to the drive axle. The twisting force at the drive axle is converted to a linear force where the tire tread meets the road surface. The linear force is measured in pounds and pushes the car forward.
We can easily calculate the linear force that accelerates the car knowing only the torque at the drive axle and the diameter of the tires.
Linear force = Axle Torque / Tire Diameter / 2
The torque exerted by the engine varies with rpm and is typically expressed as a curve. The curve is the collection of instantaneous torque measurements at each rpm point.
Neglecting driveline losses, the axle torque and linear force that pushes the car are directly proportional to the crankshaft torque for a given gear. That means that, for a given gear and neglecting air resistance, the car will always accelerate at the same rate whenever the engine is producing a given torque. It doesn't matter what RPM the engine is turning or the speed of the vehicle. A perfectly flat torque curve would allow the car to accelerate the same at any RPM.
In the real world torque curves are not flat, they build to peak and then taper off at high RPM. A car will accelerate hardest in a given gear when the engine is operating at its torque peak.
Notice that we can figure out how hard the car is accelerating and horsepower doesn't even enter into the discussion.
Horsepower - Horsepower is a measure of the rate at which work can be performed. Motion and time are integral to horsepower which is typically expressed as foot pounds per minute in the US.
In this case work has nothing to do with your boss. Work means moving an object in opposition to a force (that may remind some of their boss). Raising one pound a distance of one foot is one foot pound of work. Raising one pound a distance of two feet is two foot pounds of work.
Horsepower combines the concept of work with time. In the 1700s James Watt of steam engine fame took some measurements and concluded that an average horse could lift a 550 pound weight one foot in one second. Watt defined one horsepower as 550 foot pounds per second or 33,000 foot pounds per minute.
We can show a direct relationship between torque and horsepower. Remember our one foot lever arm with the pivot at one end and one pound force at the other? If it rotates about the pivot one full revolution in one minute it will move that one pound 2*pi*r or 6.28 feet per minute (think about a point on a tire tread rotating about its axle). If it rotates at 5252 RPM it will move that one pound 6.28 * 5252 or 33,000 feet per minute, exactly one horsepower. Hence the relationship between horsepower and torque is defined as follows:
Horsepower = torque * RPM / 5252
This is a linear relationship and says that horsepower will rise in lockstep with RPM and torque. The horsepower produced by an engine varies with rpm and is typically expressed as a curve. The curve is simply the collection of instantaneous horsepower calculations at each rpm point.
To review we know that a) axle torque converted to linear force accelerates the car b) for a given gear the acceleration will be greatest at the engine torque peak and has nothing to do with RPM or speed c) horsepower is a calculated function of torque and RPM.
So horsepower doesn't matter, right? Wrong! Read on.
Torque multiplication - The transmission is a torque multiplier. Reduction gears are employed to make the drive shaft rotate at a slower RPM than the crank shaft (ignoring overdrive). These reduction gears cause a similar increase in the drive shaft torque.
As an example a hypothetical two-speed transmission might have a first gear with a 2:1 reduction gears and a second gear with 1:1 gears. Let's connect that transmission to a an engine that can produce 100 foot pounds of torque at the crank shaft throughout the RPM range.
The 1:1 second gear rotates the drive shaft at the same speed as the crankshaft and it will exert exactly the same 100 foot pounds of torque (neglecting frictional losses). However the 2:1 first gear rotates the drive shaft at half the speed of the crankshaft but it will exert 200 foot lbs of torque, twice the torque of the crank shaft! That means first gear will accelerate the car twice as hard as second gear.
Therein lies the key to why we care about horsepower. Through reduction gears maximum drive axle torque for a given vehicle speed is generated when the engine is operating at its horsepower peak and not its torque peak (they are rarely the same).
As an example recall our car with two speeds, flat torque curve, 100 foot pound engine. Imagine it has a 1:1 final drive ratio that propels the car at 107 mph (makes the math simple) at 1500 RPM in second gear using 24 inch diameter tires. We can also drive the car 107 mph at 3000 RPM in first gear. The engine is producing 100 foot pounds of torque in both cases. Which one accelerates the car faster?
The answer of course is first gear.
As a result of torque multiplication a car will accelerate fastest at any given MPH when a gear is selected that puts the engine at its horsepower peak and not its torque peak. This is one reason why small high-revving engines can often beat large low-revving engines. Despite a lower crankshaft torque, the high-revving engine can deliver greater drive axle torque through torque multiplication.
So there it is, torque and horsepower. It seems that horsepower is good for selling cars AND winning races.
08-13-2003, 05:28 PM
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Re: Where Torque Comes From (SleepEMike)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SleepEMike »</TD></TR><TR><TD CLASS="quote">Good read. 
</TD></TR></TABLE>
VANDIT!
</TD></TR></TABLE>VANDIT!
08-13-2003, 05:42 PM
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Re: Where Torque Comes From (fivespeedintegra)
nice article!!
torque is a much easier to understand than power. i think most people just confuse the 2 or can't tell them apart. i didn't know the difference until i took physics at school!
torque is a much easier to understand than power. i think most people just confuse the 2 or can't tell them apart. i didn't know the difference until i took physics at school!
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08-13-2003, 09:54 PM
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Re: Where Torque Comes From (fivespeedintegra)
The article that fivespeedintegra has posted was a good one.
Well, here is my two cent on this topic.
well power or horse power is produce when fuel and air are burn. The expansion of the flame front forces the piston downward. Now this downward motion turns the crack shaft or twist. The twisting motion is called torque. So - torque is produce by the down stroke force of the piston.
Now how is torque produce you ask... didn't you ever wonder how come a high horse B-series v-tec produce so much horse power? but yet produces so little torque?
Well... have ever tried to break a bolt lose with a short ratch and no matter how much force(power) that you apply it's hard as hell to break lose; and, you end up breaking your knockles instead? Then when you use a longer ratch it's easy as hell to break the bolt lose?
Okay... if the bolt was the flywheel,transmission, and axles, the ratch is the crack, and me as the piston and rod - force that I apply is Horse Power. Now, 1.8 v-tec as a 85mm stroke vs a non v-tec motor 1.8 which as a 89mm stoke - Now, when your trying to break a bolt lose and when a extension bar is added the torque is double this is the reason why is much easier to break a bolt lose. now this theory applies the motor as well..
this is the reason why motors with a bigger stroke produce so much torque.
However, rod ratio also affect torque results. Now, my theory on short and long rod ratio is leverage. a longer rod ratio dwells longer at TDC and produces more force on the downward motion vs a short rod ratio. However, with a long rod ratio you unable rev as quicky(not rev so high like the v-tec motors).
Well that's it
Modified by HONDADNA at 7:39 AM 8/14/2003
Modified by HONDADNA at 7:40 AM 8/14/2003
Well, here is my two cent on this topic.
well power or horse power is produce when fuel and air are burn. The expansion of the flame front forces the piston downward. Now this downward motion turns the crack shaft or twist. The twisting motion is called torque. So - torque is produce by the down stroke force of the piston.
Now how is torque produce you ask... didn't you ever wonder how come a high horse B-series v-tec produce so much horse power? but yet produces so little torque?
Well... have ever tried to break a bolt lose with a short ratch and no matter how much force(power) that you apply it's hard as hell to break lose; and, you end up breaking your knockles instead? Then when you use a longer ratch it's easy as hell to break the bolt lose?
Okay... if the bolt was the flywheel,transmission, and axles, the ratch is the crack, and me as the piston and rod - force that I apply is Horse Power. Now, 1.8 v-tec as a 85mm stroke vs a non v-tec motor 1.8 which as a 89mm stoke - Now, when your trying to break a bolt lose and when a extension bar is added the torque is double this is the reason why is much easier to break a bolt lose. now this theory applies the motor as well..
this is the reason why motors with a bigger stroke produce so much torque.
However, rod ratio also affect torque results. Now, my theory on short and long rod ratio is leverage. a longer rod ratio dwells longer at TDC and produces more force on the downward motion vs a short rod ratio. However, with a long rod ratio you unable rev as quicky(not rev so high like the v-tec motors).
Well that's it
Modified by HONDADNA at 7:39 AM 8/14/2003
Modified by HONDADNA at 7:40 AM 8/14/2003
08-14-2003, 12:52 AM
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Re: Where Torque Comes From (HONDADNA)
the force, or torque, is made from compressing air and gas in your engine and igniting them.
you can increase torque at any given point if you
a) increase the total amount of air/fuel pushed in; done via increasing displacement, turbo, SC, or nitrous.
b) Make the air/fuel your engine can injest more efficient; increase compression/cam/ignition/ A/F tuning/etc.
c) Allow the engine more time to transfer the power... think this is where an engine w/ a small bore but long stroke makes more torque than an engine w/ a big bore and short stroke if both have the same displacements?
really your 2 choices are to add more air+fuel, or to make the air+fuel you have more efficient.
you can increase torque at any given point if you
a) increase the total amount of air/fuel pushed in; done via increasing displacement, turbo, SC, or nitrous.
b) Make the air/fuel your engine can injest more efficient; increase compression/cam/ignition/ A/F tuning/etc.
c) Allow the engine more time to transfer the power... think this is where an engine w/ a small bore but long stroke makes more torque than an engine w/ a big bore and short stroke if both have the same displacements?
really your 2 choices are to add more air+fuel, or to make the air+fuel you have more efficient.
08-14-2003, 03:54 AM
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Re: Where Torque Comes From (TypeSH)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by TypeSH »</TD></TR><TR><TD CLASS="quote">c) Allow the engine more time to transfer the power... think this is where an engine w/ a small bore but long stroke makes more torque than an engine w/ a big bore and short stroke if both have the same displacements?</TD></TR></TABLE>
i think theres more torque from a longer stroke simply because theres more twisting leverage with the longer stroke! same displacement would equal about the same fuel+air which would equal about the same amount of down force but the longer stroke bumps the torque!
like when you have a 2 foot long torque wrench and when you push 10lbs at 1ft from pivot then you have 10ft/lbs but when you push at 2ft then youll have 20ft/lbs!
i think theres more torque from a longer stroke simply because theres more twisting leverage with the longer stroke! same displacement would equal about the same fuel+air which would equal about the same amount of down force but the longer stroke bumps the torque!
like when you have a 2 foot long torque wrench and when you push 10lbs at 1ft from pivot then you have 10ft/lbs but when you push at 2ft then youll have 20ft/lbs!
08-14-2003, 06:26 AM
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Re: Where Torque Comes From (10K2HVN)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 10K2HVN »</TD></TR><TR><TD CLASS="quote">... same displacement would equal about the same fuel+air which would equal about the same amount of down force but the longer stroke bumps the torque! ...</TD></TR></TABLE>NO! The down-force isn't the same because if you have the same displacement then the longer stroke requires a smaller bore.
Let's pretend that for the same displacement you have the same pressure in the cylinder. That's not often true, because you can't usually find two engines with the same displacement, different stroke, and they have everything else equal.
But if the displacement is the same then the piston area is inversely proportional to stroke. Torque is kinda like (pressure) * (area) * (stroke). So stroke & area cancel each other out.
Longer stroke means higher piston velocity for the same RPM. Usually that means a lower redline. So 'usually' a long-stroke engine carries a cam that's tuned for lower rpms. Lift, duration, & overlap all contribute to cylinder pressure...
To increase torque (at the same displacement) you have to increase combustion pressures. There's NO OTHER WAY! But there's many ways to increase pressure. More air (thru better breathing). Higher compression ratio. Forced induction. Exotic fuel (including nitrous)...
Let's pretend that for the same displacement you have the same pressure in the cylinder. That's not often true, because you can't usually find two engines with the same displacement, different stroke, and they have everything else equal.
But if the displacement is the same then the piston area is inversely proportional to stroke. Torque is kinda like (pressure) * (area) * (stroke). So stroke & area cancel each other out.
Longer stroke means higher piston velocity for the same RPM. Usually that means a lower redline. So 'usually' a long-stroke engine carries a cam that's tuned for lower rpms. Lift, duration, & overlap all contribute to cylinder pressure...
To increase torque (at the same displacement) you have to increase combustion pressures. There's NO OTHER WAY! But there's many ways to increase pressure. More air (thru better breathing). Higher compression ratio. Forced induction. Exotic fuel (including nitrous)...
08-14-2003, 06:33 PM
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Re: Where Torque Comes From (HONDADNA)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by HONDADNA »</TD></TR><TR><TD CLASS="quote">Now how is torque produce you ask... didn't you ever wonder how come a high horse B-series v-tec produce so much horse power? but yet produces so little torque?
Well... have ever tried to break a bolt lose with a short ratch and no matter how much force(power) that you apply it's hard as hell to break lose; and, you end up breaking your knockles instead? Then when you use a longer ratch it's easy as hell to break the bolt lose?
</TD></TR></TABLE>
True, but you got to remember something W=F*D so, you can have a lot of power (force in the formula) and it will work just as good as a longer ratch, cuz in the end they will multiply each other.
Off course, getting a longer ratch is a lot easier than going to the gym!
good thread.
CREATOR: is this what you wanted to know? or you wanted to know how you can bump Torque??
Bumping torque can be made in two ways, shorter gears or basicly head work (port&polishing, better cams, better tunning, higher compresion, higher temps).
It's really a long list.
EDIT:
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by nightryder21 »</TD></TR><TR><TD CLASS="quote">aight good info. now where in our engines' can we modify to maximize torque?</TD></TR></TABLE>
Like what i stated before, on NA engines the only way to improve torque is to improve air flow, colder intake air, bigger ports, etc...
Well... have ever tried to break a bolt lose with a short ratch and no matter how much force(power) that you apply it's hard as hell to break lose; and, you end up breaking your knockles instead? Then when you use a longer ratch it's easy as hell to break the bolt lose?
</TD></TR></TABLE>
True, but you got to remember something W=F*D so, you can have a lot of power (force in the formula) and it will work just as good as a longer ratch, cuz in the end they will multiply each other.
Off course, getting a longer ratch is a lot easier than going to the gym!
good thread.
CREATOR: is this what you wanted to know? or you wanted to know how you can bump Torque??
Bumping torque can be made in two ways, shorter gears or basicly head work (port&polishing, better cams, better tunning, higher compresion, higher temps).
It's really a long list.
EDIT:
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by nightryder21 »</TD></TR><TR><TD CLASS="quote">aight good info. now where in our engines' can we modify to maximize torque?</TD></TR></TABLE>
Like what i stated before, on NA engines the only way to improve torque is to improve air flow, colder intake air, bigger ports, etc...
08-14-2003, 07:58 PM
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Re: Where Torque Comes From (GZERO)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by GZERO »</TD></TR><TR><TD CLASS="quote">
CREATOR: is this what you wanted to know? or you wanted to know how you can bump Torque??
</TD></TR></TABLE>
Jus trying to get info and see what kind of knowledge on engine theory h-t members have. Does anybody have any of their own theories or new desings in increasing torque? Again just trying to find out whats out there and get a good meaningful disccusion.
CREATOR: is this what you wanted to know? or you wanted to know how you can bump Torque??
</TD></TR></TABLE>
Jus trying to get info and see what kind of knowledge on engine theory h-t members have. Does anybody have any of their own theories or new desings in increasing torque? Again just trying to find out whats out there and get a good meaningful disccusion.
08-14-2003, 11:55 PM
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Re: Where Torque Comes From (nightryder21)
Cams and Valve Springs, Back pressure on the Exhaust side (in it's Simplicity)
Flywheel (Tricky)
Valve Timing
There are so many factors in an engine
Flywheel (Tricky)
Valve Timing
There are so many factors in an engine
08-15-2003, 07:23 AM
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Re: (95GS-Racin)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 95GS-Racin »</TD></TR><TR><TD CLASS="quote">Now this is what Honda Tech is all about! No matter how much you know, you always can learn something new.</TD></TR></TABLE>
hellz yeah
hellz yeah
08-17-2003, 05:49 PM
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Re: (fivespeedintegra)
SCC like last month had a blurb about the miller cycle vs otto cycle (spelling?). Where you increase the amount of time the engine has to transfer the power to the drivetrain before it is exhaled, using uneven strokes for the intake and exhaust strokes. Granted its mentioned it is pointless to do so when you can simply have an engine w/ that given longer stroke the entire time allowing more air to be drawn in as well, the initial intake displacement would be kept the same.
that is an option if you had to keep displacement a certain amount set and wanted to increase torque output or efficiency.
that is an option if you had to keep displacement a certain amount set and wanted to increase torque output or efficiency.
08-18-2003, 04:44 AM
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Re: (TypeSH)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by TypeSH »</TD></TR><TR><TD CLASS="quote">... miller cycle vs otto cycle...</TD></TR></TABLE>
One 'feature' of the Otto cycle is the compression & expansion act between the same volumes. So you take air, compress it 10:1 (or whatever), then ignite the mixture. Then you expand it 10:1, and at the end of the expansion it's still above atmospheric pressure. When you open the exhaust valve you release that energy & just turn it into noise. It would be cool to have some magic crank that has, say, an 80mm stroke for compression, but a 100mm stroke for expansion. That's the general idea.
Mazda's Miller engine doesn't have a magic crank to do this, but I think it uses valve timing.
One 'feature' of the Otto cycle is the compression & expansion act between the same volumes. So you take air, compress it 10:1 (or whatever), then ignite the mixture. Then you expand it 10:1, and at the end of the expansion it's still above atmospheric pressure. When you open the exhaust valve you release that energy & just turn it into noise. It would be cool to have some magic crank that has, say, an 80mm stroke for compression, but a 100mm stroke for expansion. That's the general idea.
Mazda's Miller engine doesn't have a magic crank to do this, but I think it uses valve timing.
08-18-2003, 09:20 AM
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Re: Where Torque Comes From (nightryder21)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by nightryder21 »</TD></TR><TR><TD CLASS="quote">
Jus trying to get info and see what kind of knowledge on engine theory h-t members have. Does anybody have any of their own theories or new desings in increasing torque? Again just trying to find out whats out there and get a good meaningful disccusion.</TD></TR></TABLE>
From the info i've gathered by learning about cars, engines, etc... i guess you can pretty much say this: torque is relative to air, the more air the engine moves the more torque you can have, off course, for lower ROM torque you need to play with the exhaust, and for higher RPM the exhaust has to be free flowing but the intake can't be restrictive, at least that's MHO. anyone care to elaborate on this?
Jus trying to get info and see what kind of knowledge on engine theory h-t members have. Does anybody have any of their own theories or new desings in increasing torque? Again just trying to find out whats out there and get a good meaningful disccusion.</TD></TR></TABLE>
From the info i've gathered by learning about cars, engines, etc... i guess you can pretty much say this: torque is relative to air, the more air the engine moves the more torque you can have, off course, for lower ROM torque you need to play with the exhaust, and for higher RPM the exhaust has to be free flowing but the intake can't be restrictive, at least that's MHO. anyone care to elaborate on this?
08-18-2003, 10:59 PM
#21
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Re: Where Torque Comes From (GZERO)
This might be an over-simplification. But "torque" doesn't "come from"
anywhere. It is a "concept". It is measurement of the "by-product" of "internal-combustion". A rocket engine doesn't produce ANY "torque"(I don't think,I'm not a rocket scientest) but it does produce "thrust". I can't remember whether a rocket is internal or external combustion. I would surmise "internal" but it doesn't use air for combustion it uses controlled chemical reactions. So you see "torque" is not required to produce "power" and all "horsepower" is, "is work produced over specific period of time." Again a "concept" to understand how a device accomplishes a given task. Just my .02 cents.
Any Mechanical Engineers in the house? LOL
anywhere. It is a "concept". It is measurement of the "by-product" of "internal-combustion". A rocket engine doesn't produce ANY "torque"(I don't think,I'm not a rocket scientest) but it does produce "thrust". I can't remember whether a rocket is internal or external combustion. I would surmise "internal" but it doesn't use air for combustion it uses controlled chemical reactions. So you see "torque" is not required to produce "power" and all "horsepower" is, "is work produced over specific period of time." Again a "concept" to understand how a device accomplishes a given task. Just my .02 cents.
Any Mechanical Engineers in the house? LOL
08-19-2003, 12:50 AM
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Re: Where Torque Comes From (4crx4me)
i think it is correct to say the engine is producing torque.
torque is rotational force. The engine produces a force that turns the crankshaft that in turn turns drivetrain which turns your wheels+tires which grip the road. Where the friction between the tires and the road create a horizontal force that pushes the car forward.
a rocket does not produce torque because it doesnt produce a force that is rotating. thrust is a force that is in one direction (in the rocket's case nearly straight up).
torque is rotational force. The engine produces a force that turns the crankshaft that in turn turns drivetrain which turns your wheels+tires which grip the road. Where the friction between the tires and the road create a horizontal force that pushes the car forward.
a rocket does not produce torque because it doesnt produce a force that is rotating. thrust is a force that is in one direction (in the rocket's case nearly straight up).
08-19-2003, 04:12 AM
#23
Re: Where Torque Comes From (4crx4me)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 4crx4me »</TD></TR><TR><TD CLASS="quote">... Any Mechanical Engineers in the house? LOL</TD></TR></TABLE>Yes.
A piston engine does produce torque. In fact it produces power because it is capable of maintaining that torque at a speed greater than zero rpm.
Normally a rocket engine is internal combustion because the combustion happens IN the working fluid.
A piston engine does produce torque. In fact it produces power because it is capable of maintaining that torque at a speed greater than zero rpm.
Normally a rocket engine is internal combustion because the combustion happens IN the working fluid.
08-19-2003, 06:34 AM
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Re: Where Torque Comes From (JimBlake)
Just wondering. Take a drill for example, lets call it "Machine A". "Machine A" turns at a rapid pace, but if you start to turn an object that is producing too much of a resistance for it to turn, it will stop moving. Yet take "Machine B" that might not turn as fast but has the force to turn the the object. Could you say "Machine B" has more torque than "Machine A"? If so, how can we get our engines to act more like "Machine B"? Let's try to stay away from Turbochargers and other force inductors.
08-19-2003, 07:04 AM
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Re: Where Torque Comes From (nightryder21)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by nightryder21 »</TD></TR><TR><TD CLASS="quote">Just wondering. Take a drill for example, lets call it "Machine A". "Machine A" turns at a rapid pace, but if you start to turn an object that is producing too much of a resistance for it to turn, it will stop moving. Yet take "Machine B" that might not turn as fast but has the force to turn the the object. Could you say "Machine B" has more torque than "Machine A"? If so, how can we get our engines to act more like "Machine B"? Let's try to stay away from Turbochargers and other force inductors.</TD></TR></TABLE>
Like I said above I am niether a "Rocket Scientist" nor a Mechanical Engineer so I could be oversimplifying things. Or could be mixing up my apples with my oranges. LOL But I disagree somewhat.
It seems all a reciprocating engine "really" does is produce a rotatating axis, if you will. It doesn't really produce ANY torque until a "lever" is attached to that axis and then we can measure the way the force acts on the lever producing what we call "torque" So without the "lever" there is no way to measure the hypothical torque that is in the spinning axis So the lever in our engine example would be an output shaft. So in reality isn't the torque really produced in the transmission?
Via reduction gearing?
Beacause isn't the definition of torque "Force with a twisting axis"?
Like I said above I am niether a "Rocket Scientist" nor a Mechanical Engineer so I could be oversimplifying things. Or could be mixing up my apples with my oranges. LOL But I disagree somewhat.
It seems all a reciprocating engine "really" does is produce a rotatating axis, if you will. It doesn't really produce ANY torque until a "lever" is attached to that axis and then we can measure the way the force acts on the lever producing what we call "torque" So without the "lever" there is no way to measure the hypothical torque that is in the spinning axis So the lever in our engine example would be an output shaft. So in reality isn't the torque really produced in the transmission?
Via reduction gearing?
Beacause isn't the definition of torque "Force with a twisting axis"?