Gas vs PSD
Posting Guru
Joined: Aug 2007
Posts: 1,317
Likes: 0
From: Auburn, Wa
I invite anybody here to contact Dynojet or Mustang Dyno(the 2 major players in dyno systems) and discuss this with them.
Their dynos measure horsepower.
I'm not gonna argue it anymore unless you can provide more data than "I've done hundreds of dyno tests" blah,blah,blah.
Since you've "worked on dynos", try this next time you're on the dyno. REMOVE ALL rpm inputs from the engine into the dyno. See what shows up on the graph when you finish the pull. I've been there. I've done it. I KNOW what the result is.
JL
Their dynos measure horsepower.
I'm not gonna argue it anymore unless you can provide more data than "I've done hundreds of dyno tests" blah,blah,blah.
Since you've "worked on dynos", try this next time you're on the dyno. REMOVE ALL rpm inputs from the engine into the dyno. See what shows up on the graph when you finish the pull. I've been there. I've done it. I KNOW what the result is.
JL
OK this will be probably the First in this Thread,
you are right, Probably 8 months ago when this Dyno discussion came out Johnny said this then or when ever this came up orginally. I was sure dynos measured Torque, The truth is it depends on the Dyno. If you go to a Chassis dyno you are probably gonna be Measure in HP then Calculating torque. I did go and ask my buddy the 6-8 months ago and yes he said what you said. It just depends on the Dyno.
Posting Guru
Joined: Aug 2007
Posts: 1,317
Likes: 0
From: Auburn, Wa
Wrong wrong wrong wrong wrong wrong wrong wrong wrong,
the Engine Dyno in this article does. I dont know anyone who is gonna pull their engine to put it on an engine Dyno.
On a Chassis Dyno you accually can leave your engine in your car, you put the powered wheels on a Roller and go from there. Hold on here comes the good part. It is Measuring how fast the roller is being moved.....
HP is a Unit of measure how fast work is being done.
Torque is a Measure of How much work can be done.
back to the Chassis dyno, now if you pay attention at a Dyno when they are hooking it up. Pay attention because someone is gonna hook a Sensor up under the front of the Car that is measuring your Vehicle RPM's Between the Roller spinning and that sensor they will calculate your Torque.
Most Dynos people run on will Measure HP first, then calculate Torque.
If you don't believe me to get a Dyno run and tell the Guy to not hook up the sensor you will get only HP.
Chassis Dyno Guide - Frequently Asked Questions About Dyno Tests - Hot Rod Magazine
"How does an inertia dyno work?
Inertia dynos extrapolate horsepower output by analyzing the dyno drum's acceleration rate using a sophisticated accelerometer and computer software. An inertia dyno works only when the car is accelerating. It uses heavy roller drums of known mass mounted on bearings that allow them to freely rotate. A vehicle is placed in position on the dyno with the drive wheels sitting on the rollers. The car is placed in gear and accelerated at wide-open throttle. It takes a certain amount of time and force for the tires to accelerate the heavy rollers. The laws of physics state that acceleration rate is directly proportional to how much power the tires place on the heavy roller to get it to rotate. The dyno software monitors roller velocity and the time it takes to arrive at a rate of acceleration and estimates power at the rear wheels. Using data from an engine-mounted inductive probe, the software then graphs the power and gear-compensated engine torque against engine rpm. Some inertia dynos also attempt to estimate flywheel power and torque numbers based on mathematical models and data from additional sensors."
the Engine Dyno in this article does. I dont know anyone who is gonna pull their engine to put it on an engine Dyno.
On a Chassis Dyno you accually can leave your engine in your car, you put the powered wheels on a Roller and go from there. Hold on here comes the good part. It is Measuring how fast the roller is being moved.....
HP is a Unit of measure how fast work is being done.
Torque is a Measure of How much work can be done.
back to the Chassis dyno, now if you pay attention at a Dyno when they are hooking it up. Pay attention because someone is gonna hook a Sensor up under the front of the Car that is measuring your Vehicle RPM's Between the Roller spinning and that sensor they will calculate your Torque.
Most Dynos people run on will Measure HP first, then calculate Torque.
If you don't believe me to get a Dyno run and tell the Guy to not hook up the sensor you will get only HP.
Chassis Dyno Guide - Frequently Asked Questions About Dyno Tests - Hot Rod Magazine
"How does an inertia dyno work?
Inertia dynos extrapolate horsepower output by analyzing the dyno drum's acceleration rate using a sophisticated accelerometer and computer software. An inertia dyno works only when the car is accelerating. It uses heavy roller drums of known mass mounted on bearings that allow them to freely rotate. A vehicle is placed in position on the dyno with the drive wheels sitting on the rollers. The car is placed in gear and accelerated at wide-open throttle. It takes a certain amount of time and force for the tires to accelerate the heavy rollers. The laws of physics state that acceleration rate is directly proportional to how much power the tires place on the heavy roller to get it to rotate. The dyno software monitors roller velocity and the time it takes to arrive at a rate of acceleration and estimates power at the rear wheels. Using data from an engine-mounted inductive probe, the software then graphs the power and gear-compensated engine torque against engine rpm. Some inertia dynos also attempt to estimate flywheel power and torque numbers based on mathematical models and data from additional sensors."
Did you decide to Not read the explanation, then ask for an explanation?
Cargo Master
Joined: Jan 2005
Posts: 2,413
Likes: 11
I'm sorry I don't agree w/ that. I've felt that their argueement was that the v10 would out pull the psd. Its been my argueement that it won't. Now everybody seems to agree with me. And I said the same thing I been saying just this time I said it backwards. Instead of saying the v10 won't put pull the psd but rather the psd won't out pull the v10 and they"l the same load. I've tried several times to give the gasser praises. I think that the PSD's high point is its in a Ford SD. Just to behonest about the matter.
I don't know how a dyno actually figures its numbers. I've never worked one. However I can see how it can figure hp or tq either first or last. It looks to be it gets its data from the rpms of the tires and engine and gearing data. In the rear picture you have torque 1st. You have tq even if there is no rpm. You have rpm with no hp. Hp comes from the rpm or distance of movement. Hp is work done in a time table. The word power in horse power is very misleading. The tq is the actually work being applied. You can measure tq without rpm or hp. You can't measure rpm or hp without the other 2.
I don't know how a dyno actually figures its numbers. I've never worked one. However I can see how it can figure hp or tq either first or last. It looks to be it gets its data from the rpms of the tires and engine and gearing data. In the rear picture you have torque 1st. You have tq even if there is no rpm. You have rpm with no hp. Hp comes from the rpm or distance of movement. Hp is work done in a time table. The word power in horse power is very misleading. The tq is the actually work being applied. You can measure tq without rpm or hp. You can't measure rpm or hp without the other 2.
Senior User
Joined: Feb 2006
Posts: 257
Likes: 0
From: Kingsland, GA
It's all about the torque. Horsepower is a calculation. Torque is like being able to bench press 400lbs. Horsepower is like being able to bench press 400lbs 10 times in a minute. Since the vector for a bench press is near 0, no "real" work is done, since the displacement is near zero.
Besides Dynojet dynos lie. Not only does it give its own calculation of horsepower, but then it also adds in a fudge factor for drivetrain losses based on coefficients entered in the system by the technician. These factors also include environmental conditions also entered by the tech, which these factors are why it is not a useful tool to compare Dynojet dyno runs from different dynos, locations, times, or weather conditions. Too many human data factor errors to be consistent.
Of course, I could be making all this up. Hmmmmm.
Besides Dynojet dynos lie. Not only does it give its own calculation of horsepower, but then it also adds in a fudge factor for drivetrain losses based on coefficients entered in the system by the technician. These factors also include environmental conditions also entered by the tech, which these factors are why it is not a useful tool to compare Dynojet dyno runs from different dynos, locations, times, or weather conditions. Too many human data factor errors to be consistent.
Of course, I could be making all this up. Hmmmmm.
Posting Guru
Joined: Aug 2007
Posts: 1,317
Likes: 0
From: Auburn, Wa
It's all about the torque. Horsepower is a calculation. Torque is like being able to bench press 400lbs. Horsepower is like being able to bench press 400lbs 10 times in a minute. Since the vector for a bench press is near 0, no "real" work is done, since the displacement is near zero.
Besides Dynojet dynos lie. Not only does it give its own calculation of horsepower, but then it also adds in a fudge factor for drivetrain losses based on coefficients entered in the system by the technician. These factors also include environmental conditions also entered by the tech, which these factors are why it is not a useful tool to compare Dynojet dyno runs from different dynos, locations, times, or weather conditions. Too many human data factor errors to be consistent.
Of course, I could be making all this up. Hmmmmm.
Besides Dynojet dynos lie. Not only does it give its own calculation of horsepower, but then it also adds in a fudge factor for drivetrain losses based on coefficients entered in the system by the technician. These factors also include environmental conditions also entered by the tech, which these factors are why it is not a useful tool to compare Dynojet dyno runs from different dynos, locations, times, or weather conditions. Too many human data factor errors to be consistent.
Of course, I could be making all this up. Hmmmmm.
Ill go with Making it up....lol
Any Inertia dyno measures hp first and it Calculates Torque.
Post Fiend
Joined: Jan 2005
Posts: 26,337
Likes: 12
From: Paradise Found!
Believe what you want, but as a licenced mech engineer, and working for Caterpillar for years, dynos measure torque and calculate HP. There is no other way to do it. Torque is an instant mesurement, and HP is calculated from torque AND rpm.
"Dynamometers can measure torque, in foot-pounds; they can NOTdirectly measure horsepower. To calculate horsepower, we have to combine the torque measurement with a time measurement."
Taken from: Torque, HP, Speed
"Dynamometers can measure torque, in foot-pounds; they can NOTdirectly measure horsepower. To calculate horsepower, we have to combine the torque measurement with a time measurement."
Taken from: Torque, HP, Speed
Senior User
Joined: Feb 2006
Posts: 257
Likes: 0
From: Kingsland, GA
What about an eddy current? And inertia was the Dynojet term I was looking for. So really what you are saying is similar to what has already been said. Keep in mind, not all dynos are inertial.
Senior User
Joined: Feb 2006
Posts: 257
Likes: 0
From: Kingsland, GA
Believe what you want, but as a licenced mech engineer, and working for Caterpillar for years, dynos measure torque and calculate HP. There is no other way to do it. Torque is an instant mesurement, and HP is calculated from torque AND rpm.
"Dynamometers can measure torque, in foot-pounds; they can NOTdirectly measure horsepower. To calculate horsepower, we have to combine the torque measurement with a time measurement."
Taken from: Torque, HP, Speed
"Dynamometers can measure torque, in foot-pounds; they can NOTdirectly measure horsepower. To calculate horsepower, we have to combine the torque measurement with a time measurement."
Taken from: Torque, HP, Speed
I am with you, but these other guys just don't seem to get it.
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer
Joe Kucinski
2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)
Brett Foote
Top 10 Ford Truck Tragedies
Joe Kucinski
AEV FXL Super Duty - the Super Duty Raptor Ford Doesn't Make
Brett Foote
Lobo Vs Lobo: Proof the F-150 Lobo Should Be Even Lower!
Michael S. Palmer
Ford's 2001 Explorer Sportsman Concept Looks For a New Home
Verdad Gallardo
10 Best Ford Truck Engines We Miss the Most!
Joe Kucinski
2026 Shelby F-150 Off-Road: Better Than a Raptor R?
Brett Foote
2027 Super Duty Carhartt Package First Look: 12 Things You NEED to Know!
Michael S. Palmer
Posting Guru
Joined: Aug 2007
Posts: 1,317
Likes: 0
From: Auburn, Wa
Believe what you want, but as a licenced mech engineer, and working for Caterpillar for years, dynos measure torque and calculate HP. There is no other way to do it. Torque is an instant mesurement, and HP is calculated from torque AND rpm.
"Dynamometers can measure torque, in foot-pounds; they can NOTdirectly measure horsepower. To calculate horsepower, we have to combine the torque measurement with a time measurement."
Taken from: Torque, HP, Speed
"Dynamometers can measure torque, in foot-pounds; they can NOTdirectly measure horsepower. To calculate horsepower, we have to combine the torque measurement with a time measurement."
Taken from: Torque, HP, Speed
if you take your vehicle to a chassis dyno it will measure the speed of the drum your are turning under the wheel. it will give you hp they take that and use the rpm of the engine to calculate Torque.
if they don't hook up the sensor you will get only HP.
Senior User
Joined: Feb 2006
Posts: 257
Likes: 0
From: Kingsland, GA
Uhmm there is another way to do, math works both ways 1+2=3, 2+1=3,
if you take your vehicle to a chassis dyno it will measure the speed of the drum your are turning under the wheel. it will give you hp they take that and use the rpm of the engine to calculate Torque.
if they don't hook up the sensor you will get only HP.
if you take your vehicle to a chassis dyno it will measure the speed of the drum your are turning under the wheel. it will give you hp they take that and use the rpm of the engine to calculate Torque.
if they don't hook up the sensor you will get only HP.
Dynamometer - Wikipedia, the free encyclopedia
Post Fiend
Joined: Jan 2005
Posts: 26,337
Likes: 12
From: Paradise Found!
Still not convinced?
"Here is an example of another way horsepower could be directly measured. Say you have a horse hitched to a plow. In the hitch is a spring scale (like a fish scale). The horse pulls the plow one foot every second and you see 550 pounds on the scale. That horse would be generating one horsepower.
We see horsepower can be directly measured. However there is a problem directly measuring horsepower of modern day internal combustion engines because they produce rotary motion not linear motion, and unless the engine is geared down, the speed at which they do work (time and distance or RPM) is too great for practical direct measurement of horsepower. It seems logical then that the solution was to directly measure torque (rotational force eventually expressed in pounds at one foot radius) and RPM (time and distance, i.e. distance in circumference at the one foot radius) and from these calculate horsepower. Torque and RPM are easily measured directly. Early dynamometers used a brake device to load the engine. A torque arm was attached to this brake's stator. The brake's rotor was coupled to the engine's crankshaft. A spring scale or other measuring device connected the torque arm to the stationary fixture holding the engine and brake. During a test the brake's application loaded the engine. Torque and engine rpm were observed and recorded. Click here for a description of how this happens on our dyno. On modern day dynamometers horsepower is a calculated value. It's important to remember the dyno measures torque and rpm and then from these calculates horsepower. On the dyno it takes more water flow to the water brake to increase the load on the engine being tested. As the test engine's torque rises more water flow is needed. As the test engine's torque drops less water flow is needed. The dyno's water brake does not respond to Horsepower. Major adjustments to water flow are needed as an engine crosses its torque peak but none are needed as it crosses its horsepower peak. In other words the water flow to the brake during a dyno test follows the engines torque curve and not its horsepower curve. Torque is what twists the tire, prop, or pump. Horsepower helps us understand an amount or quantity of torque. (Torque + time and distance)"
From: RevSearch Engine Dyno; Torque vs Horsepower
Funny thing is, I don't have a dog in this race! I don't have a V-10 OR a powerstroke....
"Here is an example of another way horsepower could be directly measured. Say you have a horse hitched to a plow. In the hitch is a spring scale (like a fish scale). The horse pulls the plow one foot every second and you see 550 pounds on the scale. That horse would be generating one horsepower.
We see horsepower can be directly measured. However there is a problem directly measuring horsepower of modern day internal combustion engines because they produce rotary motion not linear motion, and unless the engine is geared down, the speed at which they do work (time and distance or RPM) is too great for practical direct measurement of horsepower. It seems logical then that the solution was to directly measure torque (rotational force eventually expressed in pounds at one foot radius) and RPM (time and distance, i.e. distance in circumference at the one foot radius) and from these calculate horsepower. Torque and RPM are easily measured directly. Early dynamometers used a brake device to load the engine. A torque arm was attached to this brake's stator. The brake's rotor was coupled to the engine's crankshaft. A spring scale or other measuring device connected the torque arm to the stationary fixture holding the engine and brake. During a test the brake's application loaded the engine. Torque and engine rpm were observed and recorded. Click here for a description of how this happens on our dyno. On modern day dynamometers horsepower is a calculated value. It's important to remember the dyno measures torque and rpm and then from these calculates horsepower. On the dyno it takes more water flow to the water brake to increase the load on the engine being tested. As the test engine's torque rises more water flow is needed. As the test engine's torque drops less water flow is needed. The dyno's water brake does not respond to Horsepower. Major adjustments to water flow are needed as an engine crosses its torque peak but none are needed as it crosses its horsepower peak. In other words the water flow to the brake during a dyno test follows the engines torque curve and not its horsepower curve. Torque is what twists the tire, prop, or pump. Horsepower helps us understand an amount or quantity of torque. (Torque + time and distance)"
From: RevSearch Engine Dyno; Torque vs Horsepower
Funny thing is, I don't have a dog in this race! I don't have a V-10 OR a powerstroke....
Posting Guru
Joined: Aug 2007
Posts: 1,317
Likes: 0
From: Auburn, Wa
That is only true for intertial dynos as mentioned above.
Dynamometer - Wikipedia, the free encyclopedia
Dynamometer - Wikipedia, the free encyclopedia
which is what you are gonna be on more then likely when you take your vehicle to the shop to get it Dynoed is.
Posting Guru
Joined: Aug 2007
Posts: 1,317
Likes: 0
From: Auburn, Wa
Still not convinced?
"Here is an example of another way horsepower could be directly measured. Say you have a horse hitched to a plow. In the hitch is a spring scale (like a fish scale). The horse pulls the plow one foot every second and you see 550 pounds on the scale. That horse would be generating one horsepower.
We see horsepower can be directly measured. However there is a problem directly measuring horsepower of modern day internal combustion engines because they produce rotary motion not linear motion, and unless the engine is geared down, the speed at which they do work (time and distance or RPM) is too great for practical direct measurement of horsepower. It seems logical then that the solution was to directly measure torque (rotational force eventually expressed in pounds at one foot radius) and RPM (time and distance, i.e. distance in circumference at the one foot radius) and from these calculate horsepower. Torque and RPM are easily measured directly. Early dynamometers used a brake device to load the engine. A torque arm was attached to this brake's stator. The brake's rotor was coupled to the engine's crankshaft. A spring scale or other measuring device connected the torque arm to the stationary fixture holding the engine and brake. During a test the brake's application loaded the engine. Torque and engine rpm were observed and recorded. Click here for a description of how this happens on our dyno. On modern day dynamometers horsepower is a calculated value. It's important to remember the dyno measures torque and rpm and then from these calculates horsepower. On the dyno it takes more water flow to the water brake to increase the load on the engine being tested. As the test engine's torque rises more water flow is needed. As the test engine's torque drops less water flow is needed. The dyno's water brake does not respond to Horsepower. Major adjustments to water flow are needed as an engine crosses its torque peak but none are needed as it crosses its horsepower peak. In other words the water flow to the brake during a dyno test follows the engines torque curve and not its horsepower curve. Torque is what twists the tire, prop, or pump. Horsepower helps us understand an amount or quantity of torque. (Torque + time and distance)"
From: RevSearch Engine Dyno; Torque vs Horsepower
Funny thing is, I don't have a dog in this race! I don't have a V-10 OR a powerstroke....
"Here is an example of another way horsepower could be directly measured. Say you have a horse hitched to a plow. In the hitch is a spring scale (like a fish scale). The horse pulls the plow one foot every second and you see 550 pounds on the scale. That horse would be generating one horsepower.
We see horsepower can be directly measured. However there is a problem directly measuring horsepower of modern day internal combustion engines because they produce rotary motion not linear motion, and unless the engine is geared down, the speed at which they do work (time and distance or RPM) is too great for practical direct measurement of horsepower. It seems logical then that the solution was to directly measure torque (rotational force eventually expressed in pounds at one foot radius) and RPM (time and distance, i.e. distance in circumference at the one foot radius) and from these calculate horsepower. Torque and RPM are easily measured directly. Early dynamometers used a brake device to load the engine. A torque arm was attached to this brake's stator. The brake's rotor was coupled to the engine's crankshaft. A spring scale or other measuring device connected the torque arm to the stationary fixture holding the engine and brake. During a test the brake's application loaded the engine. Torque and engine rpm were observed and recorded. Click here for a description of how this happens on our dyno. On modern day dynamometers horsepower is a calculated value. It's important to remember the dyno measures torque and rpm and then from these calculates horsepower. On the dyno it takes more water flow to the water brake to increase the load on the engine being tested. As the test engine's torque rises more water flow is needed. As the test engine's torque drops less water flow is needed. The dyno's water brake does not respond to Horsepower. Major adjustments to water flow are needed as an engine crosses its torque peak but none are needed as it crosses its horsepower peak. In other words the water flow to the brake during a dyno test follows the engines torque curve and not its horsepower curve. Torque is what twists the tire, prop, or pump. Horsepower helps us understand an amount or quantity of torque. (Torque + time and distance)"
From: RevSearch Engine Dyno; Torque vs Horsepower
Funny thing is, I don't have a dog in this race! I don't have a V-10 OR a powerstroke....
.... Depending on the dyno you can measure it either way. But on a Chassis dyno that you take your vehicle to it will measure HP. I showed you Professor in the simplest form of math how it works both ways.
HOMEWORK: go do 2 dyno pulls on a Chassis dyno on the second one tell the dyno operator to not hook up the sensor to measure your engine speed come back and report your finding with the graphs and show everyone.
Senior User
Joined: Feb 2006
Posts: 257
Likes: 0
From: Kingsland, GA
True statement. Dynojets are relatively cheap, therefore popular. My experience has been with Factory Pro eddy current dynos, and I have greater respect for their results. Dynojets are great for when its time to brag since they tend to have a significantly higher result. But again, comparing Dynojet dyno numbers under most conditions is futile.
Senior User
Joined: Feb 2006
Posts: 257
Likes: 0
From: Kingsland, GA
I've had a PSD for 2 weeks now after 5 years with a 5.4 and all I can say is I don't see a reason to ever buy a gas truck as long as I have to tow or haul something. Gassers just don't know what's up.