micksvrs
QUOTE (Brian.G @ Jul 11 2009, 06:24 PM) <{POST_SNAPBACK}>And to go with that:
Horsepower= Torque x RPM divided by 5252.
whered you get that?
my car was 122 hp 133.4 ft/lb at 5400 rpm which would equal 137.15
Horsepower= Torque x RPM divided by 5252.
whered you get that?
my car was 122 hp 133.4 ft/lb at 5400 rpm which would equal 137.15
QUOTE (Oakgreen @ Jul 11 2009, 06:33 PM) <{POST_SNAPBACK}>whered you get that?
my car was 122 hp 133.4 ft/lb at 5400 rpm which would equal 137.15
its the un-bendable rule sean
![Image]()
my car was 122 hp 133.4 ft/lb at 5400 rpm which would equal 137.15
its the un-bendable rule sean
QUOTE (Oakgreen @ Jul 11 2009, 06:33 PM) <{POST_SNAPBACK}>whered you get that?
my car was 122 hp 133.4 ft/lb at 5400 rpm which would equal 137.15
sorry got my figures wrong the print out says:122hp
133.4 ft/lb
5730rpm
using the formula above and figures on my print out would give me,145.54 hp
my car was 122 hp 133.4 ft/lb at 5400 rpm which would equal 137.15
sorry got my figures wrong the print out says:122hp
133.4 ft/lb
5730rpm
using the formula above and figures on my print out would give me,145.54 hp
QUOTE (Oakgreen @ Jul 11 2009, 06:33 PM) <{POST_SNAPBACK}>using the formula above and figures on my print out would give me,145.54 hp
nice!
nice!
QUOTE (Oakgreen @ Jul 11 2009, 06:33 PM) <{POST_SNAPBACK}>whered you get that?
my car was 122 hp 133.4 ft/lb at 5400 rpm which would equal 137.15
its been engraved in the inside of my head from birth.
If the power and torque plots on the printed graph dont intersect at exactly 5252 rpm the rolling road is possibly telling lies or setup wrong
![Image]()
like so below, im sure Joe will expand on this more, and when the 5252 constant apply's.
![Image]()
my car was 122 hp 133.4 ft/lb at 5400 rpm which would equal 137.15
its been engraved in the inside of my head from birth.
If the power and torque plots on the printed graph dont intersect at exactly 5252 rpm the rolling road is possibly telling lies or setup wrong
like so below, im sure Joe will expand on this more, and when the 5252 constant apply's.
I always knew the 5252 rule aswell..is there absolutely no exceptions? Not even high rpm engines , like superbikes or F1 cars? Not doubting ye , just my curious mind. And why does it happen there?
QUOTE (razor @ Jul 12 2009, 03:37 PM) <{POST_SNAPBACK}>well RPM is a subsatute for torque so i dont know how you'd work the rule there
I lifted this from my project blog im currently writing :
4. Torque, A Simple Explanation.
You are probably familiar with the terms Horsepower and Torque, and it is highly likely that you have seen them wrote all over the internet, in car books, specs, graphs, etc. Both are regularly used in the car industry and are considered the standard in terms of rating the performance of a car's engine,
The question is though, what exactly are these units, and how do they relate to how well an engine can actually perform?
Let me start lightly on trying to explain what both are, it'll get more complex as you read on but if you understand everything as you go it will make sense I promise.
1. Torque.
Torque is a measurement of turning force an engine has.
The very same as if you were undoing a really tight bolt with a wrench, its the maximum amount of twisting force that can be applied.
Take for example a bolt that's very tight, you take a wrench to it,if the wrench was only a meter long and you applied 100kg force to it then its turning force on the bolt would only be 100 Newton meters(Nm)
Take for example the same bolt, you take another wrench to it, say for example a wrench 2meters long for ease of example, if you apply a force of 100kg to the end of the wrench then your applying 200 Newton meters of torque to that bolt.
Again another example, if the wrench were 3meters long, you apply again 100kg of force to it then you would have a turning force of 300Nm
The length of the wrench acts as a torque or force multiplier.
See the drawing below for a simple example.
![Image]()
Pretty simple so far right?
Now if we look at the drawing to the left again we can see in order to turn the bolt a full turn the end of the longer wrench will have to move through a bigger circle(circumference length would be(3.14xdiameter)= 3.14x4m=12.56m)basically it will have to travel farther(12.56m) in order to apply the greater torque.
If we applied 200kg to the short wrench it would only have to travel 6.28m(circumference length would be(3.14xdiameter)=3.14x2m=6.28m )
So we can see that if we can apply more force it takes less time or distance to do the same amount of work.
Dont let the little bit of maths above confuse you, all i did was find the circumference of the circle that the end of the wrench creates, we all did that in school.
2. Time for another one of my drawings to relate all this "wrench and bolt" talk to an actual engine, its the very same would you believe and all very simple if you take a bit at a time.
![Image]()
Now lets link all these to the engine terms.
The throw is the length of the wrench.
The bore/piston top area is what the explosion exerts the force onto, or the power of your arm acting on the end of the wrench.
The stroke is the diameter of the circle, same as the circle created by the end of the wrench.
When does and engine produce max torque?
3. An engine consists of a cylinder, piston, rod, crank, and cylinder head.
In this example lets take a single cylinder engine of say 400cc.
Meaning that the static cc of the cylinder is 400cc, for example, if the head was removed and a basic plastic lid with a large hole was placed on top of the bore the cylinder would pull in 400cc of air if turned by hand.
Pulling an rpm value completely out of the air lets say the engine made its max torque at 3000rpm, the reason for this would be that the air is at its optimum speed while entering the cylinder, the fuel is mixing with the air correctly, at the correct ratio(stoichiometric)while being completely burned at exactly the correct time and therefore applying maximum force on the piston.
Now lets increase the rpm, obstructions in the intake such as inlet design, throttle valves, head design, valve size, exhaust design, etc "slow down" the speed at which the incoming air needs to be going at in order to completely fill the cylinder at this higher rpm, resulting in a less than ideal cylinder "fill" or "charge", it simply cant keep up and therefore the explosion is not as great and therefore less in cylinder pressure and in the end, less torque.
This is called volumetric efficiency.
More correctly, volumetric efficiency is a ratio (or percentage) of what volume of fuel and air actually enters the cylinder during the induction stroke, to the actual capacity of the cylinder under static conditions, in this example, 400cc(static) as mentioned above.
An engine with a high volumetric efficiency is usually capable of higher output, as the cylinder is better able to fill and less energy is required pulling the air past any obstructions.
4. So to sum up:
Torque is the turning force an engine has, in order to make more torque, you either need to make the crank throw(wrench) longer or make the diameter of the piston bigger(power of your arm) or of course increase both.
I will cover the effects of increasing either or later on.
RPM is not a substitute for Torque, Torque is the turning force, RPM is the Rate at which this turning force is being applied to the object, in this case the big end, around its axis, mains.
Im sure Joe will fill us all in more, and if you do see this Joe, can you tell me when 5252 isent a constant in the HP formula as i need to know, Thanks!
I lifted this from my project blog im currently writing :
4. Torque, A Simple Explanation.
You are probably familiar with the terms Horsepower and Torque, and it is highly likely that you have seen them wrote all over the internet, in car books, specs, graphs, etc. Both are regularly used in the car industry and are considered the standard in terms of rating the performance of a car's engine,
The question is though, what exactly are these units, and how do they relate to how well an engine can actually perform?
Let me start lightly on trying to explain what both are, it'll get more complex as you read on but if you understand everything as you go it will make sense I promise.
1. Torque.
Torque is a measurement of turning force an engine has.
The very same as if you were undoing a really tight bolt with a wrench, its the maximum amount of twisting force that can be applied.
Take for example a bolt that's very tight, you take a wrench to it,if the wrench was only a meter long and you applied 100kg force to it then its turning force on the bolt would only be 100 Newton meters(Nm)
Take for example the same bolt, you take another wrench to it, say for example a wrench 2meters long for ease of example, if you apply a force of 100kg to the end of the wrench then your applying 200 Newton meters of torque to that bolt.
Again another example, if the wrench were 3meters long, you apply again 100kg of force to it then you would have a turning force of 300Nm
The length of the wrench acts as a torque or force multiplier.
See the drawing below for a simple example.
Pretty simple so far right?
Now if we look at the drawing to the left again we can see in order to turn the bolt a full turn the end of the longer wrench will have to move through a bigger circle(circumference length would be(3.14xdiameter)= 3.14x4m=12.56m)basically it will have to travel farther(12.56m) in order to apply the greater torque.
If we applied 200kg to the short wrench it would only have to travel 6.28m(circumference length would be(3.14xdiameter)=3.14x2m=6.28m )
So we can see that if we can apply more force it takes less time or distance to do the same amount of work.
Dont let the little bit of maths above confuse you, all i did was find the circumference of the circle that the end of the wrench creates, we all did that in school.
2. Time for another one of my drawings to relate all this "wrench and bolt" talk to an actual engine, its the very same would you believe and all very simple if you take a bit at a time.
Now lets link all these to the engine terms.
The throw is the length of the wrench.
The bore/piston top area is what the explosion exerts the force onto, or the power of your arm acting on the end of the wrench.
The stroke is the diameter of the circle, same as the circle created by the end of the wrench.
When does and engine produce max torque?
3. An engine consists of a cylinder, piston, rod, crank, and cylinder head.
In this example lets take a single cylinder engine of say 400cc.
Meaning that the static cc of the cylinder is 400cc, for example, if the head was removed and a basic plastic lid with a large hole was placed on top of the bore the cylinder would pull in 400cc of air if turned by hand.
Pulling an rpm value completely out of the air lets say the engine made its max torque at 3000rpm, the reason for this would be that the air is at its optimum speed while entering the cylinder, the fuel is mixing with the air correctly, at the correct ratio(stoichiometric)while being completely burned at exactly the correct time and therefore applying maximum force on the piston.
Now lets increase the rpm, obstructions in the intake such as inlet design, throttle valves, head design, valve size, exhaust design, etc "slow down" the speed at which the incoming air needs to be going at in order to completely fill the cylinder at this higher rpm, resulting in a less than ideal cylinder "fill" or "charge", it simply cant keep up and therefore the explosion is not as great and therefore less in cylinder pressure and in the end, less torque.
This is called volumetric efficiency.
More correctly, volumetric efficiency is a ratio (or percentage) of what volume of fuel and air actually enters the cylinder during the induction stroke, to the actual capacity of the cylinder under static conditions, in this example, 400cc(static) as mentioned above.
An engine with a high volumetric efficiency is usually capable of higher output, as the cylinder is better able to fill and less energy is required pulling the air past any obstructions.
4. So to sum up:
Torque is the turning force an engine has, in order to make more torque, you either need to make the crank throw(wrench) longer or make the diameter of the piston bigger(power of your arm) or of course increase both.
I will cover the effects of increasing either or later on.
RPM is not a substitute for Torque, Torque is the turning force, RPM is the Rate at which this turning force is being applied to the object, in this case the big end, around its axis, mains.
Im sure Joe will fill us all in more, and if you do see this Joe, can you tell me when 5252 isent a constant in the HP formula as i need to know, Thanks!
QUOTE (Tristan @ Jul 12 2009, 03:20 PM) <{POST_SNAPBACK}>I always knew the 5252 rule aswell..is there absolutely no exceptions? Not even high rpm engines , like superbikes or F1 cars? Not doubting ye , just my curious mind. And why does it happen there?
The 5252 'rule' is just maths. It comes from working out the units so that you get your power output expessed in bhp. So there are never any exceptions.
Power is the rate at which work is done.
In rotational systems like engines Power = Torque x angular velocity
Now normally engine speed is expressed in RPM but the SI units for angular velocity are radians per second so to convert from rpm to rad/s you multiply by 2xPI and divide by 60.
Torque is usually expressed in lb/ft.
So using the equation above would give us power expressed in foot pounds per second. But we want it in bhp. 1 bhp is 550 lb/ft per second so dividing by 550 will give us our answer in bhp.
So we end up multiplying by 2PI, divide by 60 and then divide by 550. So that is 33000 divided by 2PI, which is 5252.
The 5252 'rule' is just maths. It comes from working out the units so that you get your power output expessed in bhp. So there are never any exceptions.
Power is the rate at which work is done.
In rotational systems like engines Power = Torque x angular velocity
Now normally engine speed is expressed in RPM but the SI units for angular velocity are radians per second so to convert from rpm to rad/s you multiply by 2xPI and divide by 60.
Torque is usually expressed in lb/ft.
So using the equation above would give us power expressed in foot pounds per second. But we want it in bhp. 1 bhp is 550 lb/ft per second so dividing by 550 will give us our answer in bhp.
So we end up multiplying by 2PI, divide by 60 and then divide by 550. So that is 33000 divided by 2PI, which is 5252.
QUOTE (Brian.G @ Jul 12 2009, 04:17 PM) <{POST_SNAPBACK}>Take for example a bolt that's very tight, you take a wrench to it,if the wrench was only a meter long and you applied 100kg force to it then its turning force on the bolt would only be 100 Newton meters(Nm)
mass x g(9.81)=newtons
therefore 100kg x 9.81 = 981N x 1m = 981Nm or so
mass x g(9.81)=newtons
therefore 100kg x 9.81 = 981N x 1m = 981Nm or so
QUOTE (Brian.G @ Jul 12 2009, 07:40 PM) <{POST_SNAPBACK}>So why are these crossing at 4250 taking all the above into account?
![Image]()
You are correct at what you are saying , but only if its LBFT and engine HP in the same context EG at the flywheel , and if the 2 scalings are exactly the same EG 0 to 300
on both TQ and HP will it intersect at the Constant 5252
I think mistakenly put it to wheel TQ instead of crank where the HP was left in Crank
![Image]()
Will I ever be forgiven
![Image]()
You are correct at what you are saying , but only if its LBFT and engine HP in the same context EG at the flywheel , and if the 2 scalings are exactly the same EG 0 to 300
on both TQ and HP will it intersect at the Constant 5252
I think mistakenly put it to wheel TQ instead of crank where the HP was left in Crank
QUOTE (Joe@Chipped Ireland @ Jul 12 2009, 08:21 PM) <{POST_SNAPBACK}>You are correct at what you are saying , but only if its LBFT and engine HP in the same context EG at the flywheel , and if the 2 scalings are exactly the same EG 0 to 300
on both TQ and HP will it intersect at the Constant 5252
I think mistakenly put it to wheel TQ instead of crank where the HP was left in Crank
![Image]()
Will I ever be forgiven
![Image]()
thanks for that Joe, i knew something wasent adding up, it was an easy mistake to make when setting up the run, and what an extremely informative post it brought about for all. I FORGIVE YOU!!!!! ,
![Image]()
![Image]()
@ mick, T=distance x force.
force and mass are different.
on both TQ and HP will it intersect at the Constant 5252
I think mistakenly put it to wheel TQ instead of crank where the HP was left in Crank
thanks for that Joe, i knew something wasent adding up, it was an easy mistake to make when setting up the run, and what an extremely informative post it brought about for all. I FORGIVE YOU!!!!! ,
@ mick, T=distance x force.
force and mass are different.
QUOTE (Brian.G @ Jul 12 2009, 08:28 PM) <{POST_SNAPBACK}>@ mick, T=distance x force.
force and mass are different.
1kg of mass is equal to 9.81 Newtons (force)
So if a mass of 100kg generates a force of 981N, and is placed on a lever one meter long, that creates a torque of 981Nm, as opposed to 100Nm..
![Image]()
therefore your above paragraph isint correct on that fact at least..
force and mass are different.
1kg of mass is equal to 9.81 Newtons (force)
So if a mass of 100kg generates a force of 981N, and is placed on a lever one meter long, that creates a torque of 981Nm, as opposed to 100Nm..
therefore your above paragraph isint correct on that fact at least..
yup, i need to use ft pounds instead
![Image]()
which will prob suit me further on when the blog gets complex and finalised.
QUOTE (Davec @ Jul 12 2009, 09:26 PM) <{POST_SNAPBACK}>www.geeksareus.com.......
![Image]()
Nice to have things right
![Image]()
Nice to have things right
QUOTE (Alan B. @ Jul 12 2009, 10:07 PM) <{POST_SNAPBACK}>ha ha, i read only bits of this thread as i faded in and out while drinking....
sort of get it but i'll read the bits i skipped later and come to my own conclusion...
![Image]()
![Image]()
happy bday by the way!
sort of get it but i'll read the bits i skipped later and come to my own conclusion...
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
