Synergy Twin dyno results....two dynos
08-11-2007, 10:33 AM
#21
Originally Posted by Yogi Bear
It HAS to measure torque. That's the only way to get HP. There is no instrument or machine that can "measure" HP. HP is calculated based on torque and RPM.
08-11-2007, 02:13 PM
#22
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Originally Posted by kp
Dynojets calculate horsepower using a time/weight(fixed)/speed of the drum formula and then calculates the torque using the engine rpm. If you leave the rpm pickup off a dynojet you will get HP readings but no torque.
but torque is whats going to spin the drum not hp.. to the best of my knowledge there is no measure for hp as hp is merely a figment of your imagination.. its nothing more than a mathmatical equation used for comparison purposes.. it hp= torque X rpm /5252
which is why even on a dyno jet the hp and torque reading HAVE to cross at 5252 or the settings are out of whack.. because its using that equation as well.. which as you will notice in bothe graphs posted they would cross there.. because that equation is being used..
if you had a 1000hp motor that produced less than 1 ft lb of torque while not rationally possible to build said motor wouldn't even be able to turn the drum.. so how does the dynojet measure its hp?? it can't.. if you loose signal it may give you a best guess scenario or something.. but with out a torque reading you can't have a hp reading period..
Mike
08-11-2007, 02:23 PM
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Originally Posted by blacktransam
but torque is whats going to spin the drum not hp.. to the best of my knowledge there is no measure for hp as hp is merely a figment of your imagination.. its nothing more than a mathmatical equation used for comparison purposes.. it hp= torque X rpm /5252
which is why even on a dyno jet the hp and torque reading HAVE to cross at 5252 or the settings are out of whack.. because its using that equation as well.. which as you will notice in bothe graphs posted they would cross there.. because that equation is being used..
if you had a 1000hp motor that produced less than 1 ft lb of torque while not rationally possible to build said motor wouldn't even be able to turn the drum.. so how does the dynojet measure its hp?? it can't.. if you loose signal it may give you a best guess scenario or something.. but with out a torque reading you can't have a hp reading period..
Mike
which is why even on a dyno jet the hp and torque reading HAVE to cross at 5252 or the settings are out of whack.. because its using that equation as well.. which as you will notice in bothe graphs posted they would cross there.. because that equation is being used..
if you had a 1000hp motor that produced less than 1 ft lb of torque while not rationally possible to build said motor wouldn't even be able to turn the drum.. so how does the dynojet measure its hp?? it can't.. if you loose signal it may give you a best guess scenario or something.. but with out a torque reading you can't have a hp reading period..
Mike
More info on dynos here.
08-11-2007, 03:27 PM
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Just because you read what a Dyno is supposed to do, does not mean that a dyno is designed that way. Go talk Dynojet, or others that own one, and you will find your real answer, and then you will understand its good and weak points.
Rick
Rick
08-11-2007, 03:28 PM
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Originally Posted by blacktransam
but torque is whats going to spin the drum not hp.. to the best of my knowledge there is no measure for hp as hp is merely a figment of your imagination.. its nothing more than a mathmatical equation used for comparison purposes.. it hp= torque X rpm /5252
which is why even on a dyno jet the hp and torque reading HAVE to cross at 5252 or the settings are out of whack.. because its using that equation as well.. which as you will notice in bothe graphs posted they would cross there.. because that equation is being used..
if you had a 1000hp motor that produced less than 1 ft lb of torque while not rationally possible to build said motor wouldn't even be able to turn the drum.. so how does the dynojet measure its hp?? it can't.. if you loose signal it may give you a best guess scenario or something.. but with out a torque reading you can't have a hp reading period..
Mike
which is why even on a dyno jet the hp and torque reading HAVE to cross at 5252 or the settings are out of whack.. because its using that equation as well.. which as you will notice in bothe graphs posted they would cross there.. because that equation is being used..
if you had a 1000hp motor that produced less than 1 ft lb of torque while not rationally possible to build said motor wouldn't even be able to turn the drum.. so how does the dynojet measure its hp?? it can't.. if you loose signal it may give you a best guess scenario or something.. but with out a torque reading you can't have a hp reading period..
Mike
Rick
08-11-2007, 03:58 PM
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Originally Posted by Rick@Synergy
Just because you read what a Dyno is supposed to do, does not mean that a dyno is designed that way. Go talk Dynojet, or others that own one, and you will find your real answer, and then you will understand its good and weak points.
Rick
Rick
You and KP are obviously know how to operate a Dynojet very well, you just don't know where the numbers come from. Blacktransam explained the numbers very well. The Wiki story confirms what he said.
08-11-2007, 04:34 PM
#27
Originally Posted by Yogi Bear
I didn't "just read" what a dyno is supposed to do. I am a mechanical engineer and I have personally designed and built a dyno before. And yes, a dyno IS designed that way. It has to be in order to provide the numbers.
You and KP are obviously know how to operate a Dynojet very well, you just don't know where the numbers come from. Blacktransam explained the numbers very well. The Wiki story confirms what he said.
You and KP are obviously know how to operate a Dynojet very well, you just don't know where the numbers come from. Blacktransam explained the numbers very well. The Wiki story confirms what he said.
I smell a serious rebuttal coming.
08-11-2007, 05:03 PM
#28
Torque is not work. Torque can be placed against an object that is not moving which = no work. HP is not an imaginary measurement. HP is a measurement of work done which is the result of movement. The Dynojet measures how quickly a drum of known mass and diameter is accelerated. This is a direct measurement of WORK, therefore it is directly measuring horsepower. It then does the appropriate math with the engine rpm to figure torque. Load cell dynos are a bit more complicated.
08-11-2007, 06:27 PM
#29
Originally Posted by gametech
Torque is not work. Torque can be placed against an object that is not moving which = no work. HP is not an imaginary measurement. HP is a measurement of work done which is the result of movement. The Dynojet measures how quickly a drum of known mass and diameter is accelerated. This is a direct measurement of WORK, therefore it is directly measuring horsepower. It then does the appropriate math with the engine rpm to figure torque. Load cell dynos are a bit more complicated.
Now where did I put that darned horsepower wrench, I need to tighten my lug nuts..
08-11-2007, 06:45 PM
#30
Originally Posted by kp
Beat me to it, that pretty much sums it up right there.
Now where did I put that darned horsepower wrench, I need to tighten my lug nuts..
Now where did I put that darned horsepower wrench, I need to tighten my lug nuts..
LOL. Who cares really. If a dyno gives me a print out with a HP or TQ or AFR reading I am a happy camper. If a dyno provides me a load to better tune my car I am happy. I dont give a crap hopw it works as long as it does.
KP let me know what the Horepower wrench set ya back.
08-11-2007, 07:01 PM
#31
Originally Posted by Josh @ KYTP
KP let me know what the Horsepower wrench set ya back.
Back to the subject at hand, thanks for the comparison Rick. The dynapack is the one that bolts to the hubs correct?
08-11-2007, 08:51 PM
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Originally Posted by kp
I dont remember but I have used it for years to pay back my student loans, its a money-maker
Back to the subject at hand, thanks for the comparison Rick. The dynapack is the one that bolts to the hubs correct?
Back to the subject at hand, thanks for the comparison Rick. The dynapack is the one that bolts to the hubs correct?
yes sir it does. It also makes tuning a turbo car a whole lot easier and dead on.
Rick
08-12-2007, 02:28 AM
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Originally Posted by gametech
Torque is not work. Torque can be placed against an object that is not moving which = no work. HP is not an imaginary measurement. HP is a measurement of work done which is the result of movement. The Dynojet measures how quickly a drum of known mass and diameter is accelerated. This is a direct measurement of WORK, therefore it is directly measuring horsepower. It then does the appropriate math with the engine rpm to figure torque. Load cell dynos are a bit more complicated.
Nice comparo Rick!
Dan
08-12-2007, 02:58 AM
#36
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I found some real good info as well on the net:
PHYSICS LESSON
At the core of a Dynojet is a metal drum riding on antifriction bearings. The drum weighs about 900 lbs, is two feet in diameter and has a knurled surface to enhance traction. Because 900 lbs. takes time to slow once the dyno run is complete; the drum can have brakes, operated via a button on the dyno's controller.
A key principle of the Dynojet is: the drum's inertia acts as a sort of passive power absorption device. "Mass equivalent" is a term engineers and physicists use to quantify the difference in inertia of a mass in linear or, more properly, "translational" motion and one in rotating motion. The mass equivalent of a rotating drum is quite different than its mass for translational motion so the weight simulated by the drums when rotating is different than their actual weight.
During manufacturing, Dynojet Research figures the mass equivalent of each drum to four places and bearing drag to five places.
Those proprietary figures are figured into the computation the dyno computer makes. If the mass equivalent of the drums is known and the rate at which a vehicle's drive wheels accelerate the drums is accurately measured; then the "thrust force," in pounds, at the rear wheels can be computed with a high degree of accuracy.
A combination of two laws of physics, force equals mass times acceleration and work equals force times distance, gives us this equation: W=m X a X d. "W" is the work (in pound-feet) the rear wheel is doing, "m" is mass equivalent (the drums), "a" is acceleration (increasing drive wheel speed) and "d" is distance (drum circumference). Once we have the work, we can find horsepower. One horsepower is 550 pounds-feet of work done in one second, so we divide the work number by the length of time measured, then divide the number we get from that by 550. To simplify: we get horsepower by multiplying the mass, acceleration and the distance, then dividing that product by time multiplied by 550. This can be expressed by: hp=(m X a X d) / (t X 550).
Torque can be figured by multiplying the horsepower by a constant, 5252, then dividing that product by the speed at which the thrust force was measured. Generally with rear wheel numbers, axle ratio is not considered in the torque computation. For comparison purposes, this makes more sense. The computer factors out the axle ratio by using engine speed data in the torque derivation.
In the real world, the measurements and computations are not quite that simple, but the complex methods Dynojet Research uses to apply these laws of physics and their mathematics to accurate measurement of rear wheel power is a proprietary secret.
Power
Power in mechanical terms is the ability to accomplish a specified amount of work in a given amount of time. By definition, one horsepower is equal to applying a 550 pound force through a distance of 1 foot in one second. In real terms, it would take 1 HP to raise a 550 pound weight up 1 foot in 1 second. So to measure horsepower, we need to know force (in pounds) and velocity (in feet per second).
Dynojet's inertial dynamometer measures power according to the terms just described. It measures velocity directly by measuring the time it takes to rotate a heavy steel drum one turn. It measures force at the surface of the drum by indirectly measuring its acceleration. Acceleration is simply the difference in velocity at the surface of the drum from one revolution to the next. The force applied to the drum is calculated from acceleration using Newton's 2nd law, Force = Mass x Acceleration.
Power is coupled to the drum by friction developed between the rear tire and the knurled steel surface on the drum of the dynamometer.
Torque
When an object rotates around a point, its speed of rotation depends on both an applied force and the moment arm. The moment arm is the distance from the point of rotation to where the force is being applied. Torque is the product of the force and the moment arm. For example, if a rope, wrapped around a drum of 1 foot radius, is pulled with 550 pounds of force, the resulting torque is 550 foot-pounds.
The torque on the dyno's drum can be calculated by multiplying the force applied by the drum's radius. However, engine torque is not equal to drum torque since the gearing through the drive train changes the moment arm. The change in the moment arm is proportional to the ratio of engine speed to drum speed. Therefore tachometer readings are necessary to calculate and display engine torque.
PHYSICS LESSON
At the core of a Dynojet is a metal drum riding on antifriction bearings. The drum weighs about 900 lbs, is two feet in diameter and has a knurled surface to enhance traction. Because 900 lbs. takes time to slow once the dyno run is complete; the drum can have brakes, operated via a button on the dyno's controller.
A key principle of the Dynojet is: the drum's inertia acts as a sort of passive power absorption device. "Mass equivalent" is a term engineers and physicists use to quantify the difference in inertia of a mass in linear or, more properly, "translational" motion and one in rotating motion. The mass equivalent of a rotating drum is quite different than its mass for translational motion so the weight simulated by the drums when rotating is different than their actual weight.
During manufacturing, Dynojet Research figures the mass equivalent of each drum to four places and bearing drag to five places.
Those proprietary figures are figured into the computation the dyno computer makes. If the mass equivalent of the drums is known and the rate at which a vehicle's drive wheels accelerate the drums is accurately measured; then the "thrust force," in pounds, at the rear wheels can be computed with a high degree of accuracy.
A combination of two laws of physics, force equals mass times acceleration and work equals force times distance, gives us this equation: W=m X a X d. "W" is the work (in pound-feet) the rear wheel is doing, "m" is mass equivalent (the drums), "a" is acceleration (increasing drive wheel speed) and "d" is distance (drum circumference). Once we have the work, we can find horsepower. One horsepower is 550 pounds-feet of work done in one second, so we divide the work number by the length of time measured, then divide the number we get from that by 550. To simplify: we get horsepower by multiplying the mass, acceleration and the distance, then dividing that product by time multiplied by 550. This can be expressed by: hp=(m X a X d) / (t X 550).
Torque can be figured by multiplying the horsepower by a constant, 5252, then dividing that product by the speed at which the thrust force was measured. Generally with rear wheel numbers, axle ratio is not considered in the torque computation. For comparison purposes, this makes more sense. The computer factors out the axle ratio by using engine speed data in the torque derivation.
In the real world, the measurements and computations are not quite that simple, but the complex methods Dynojet Research uses to apply these laws of physics and their mathematics to accurate measurement of rear wheel power is a proprietary secret.
Power
Power in mechanical terms is the ability to accomplish a specified amount of work in a given amount of time. By definition, one horsepower is equal to applying a 550 pound force through a distance of 1 foot in one second. In real terms, it would take 1 HP to raise a 550 pound weight up 1 foot in 1 second. So to measure horsepower, we need to know force (in pounds) and velocity (in feet per second).
Dynojet's inertial dynamometer measures power according to the terms just described. It measures velocity directly by measuring the time it takes to rotate a heavy steel drum one turn. It measures force at the surface of the drum by indirectly measuring its acceleration. Acceleration is simply the difference in velocity at the surface of the drum from one revolution to the next. The force applied to the drum is calculated from acceleration using Newton's 2nd law, Force = Mass x Acceleration.
Power is coupled to the drum by friction developed between the rear tire and the knurled steel surface on the drum of the dynamometer.
Torque
When an object rotates around a point, its speed of rotation depends on both an applied force and the moment arm. The moment arm is the distance from the point of rotation to where the force is being applied. Torque is the product of the force and the moment arm. For example, if a rope, wrapped around a drum of 1 foot radius, is pulled with 550 pounds of force, the resulting torque is 550 foot-pounds.
The torque on the dyno's drum can be calculated by multiplying the force applied by the drum's radius. However, engine torque is not equal to drum torque since the gearing through the drive train changes the moment arm. The change in the moment arm is proportional to the ratio of engine speed to drum speed. Therefore tachometer readings are necessary to calculate and display engine torque.
08-12-2007, 03:14 AM
#37
Now if we REALLY wanted to hijack this thread, let's talk about how the original dynojets were calibrated to an imaginary HP# in motorcycle advertisements. Or we could just give props to the threadstarter for trying to give legit real world #'s on a particular powertrain combo.
08-12-2007, 02:44 PM
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Originally Posted by gametech
Now if we REALLY wanted to hijack this thread, let's talk about how the original dynojets were calibrated to an imaginary HP# in motorcycle advertisements. Or we could just give props to the threadstarter for trying to give legit real world #'s on a particular powertrain combo.
08-13-2007, 09:44 AM
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Originally Posted by RealQuick
Just to back up the hp measurement thing on a dynojet, dont take the tach signal from the plug wire and you still will get HP output, but no torque curve. That right there tells you the hp is measured first, then tq curve is back calculated.
Correct, thats why on other dynos, TQ seems to be higher in respect to HP on every car.
Rick