Do all dynos require weight input?

[oldsmokey]

Just as it says do all dynos require the weight of the truck to be put into the computer before a dyno pull, or is it just a mustang thing. I have heard that on a mustang the operator can vary the hp readout greatly by changing settings and therefore they are not the best for dyno comps. Is there any truth to this?

 

[Begle1]

Does a 500 HP engine make more horsepower in a 3000 pound vehicle or a 12,000 pound vehicle?

 

[2007 5.9]

Does a 500 HP engine make more horsepower in a 3000 pound vehicle or a 12,000 pound vehicle?

:redx:

Umm, which is faster to 100mph...a 500hp 3000lb car or a 500hp 12,000 car???

The mustang dynos need weight input to accuratly measure HP.

If the rollers on a Mustang dyno weigh 3000lbs a 500hp truck that weighs 7100lbs on the street will obviously spin the 3000lb rollers to 100mph FASTER than a car that weighs 3000lbs. The computer on the dyno needs to calculate HP based upon real world weights and the vehicles ability to spin the XXXXlb rollers.

To the OP, as far as I know the Mustang dynos are the only ones that need the vehicle weight to measure HP. I am not too sure how the other dyno's calculate weight.

 

[oldsmokey]

Does that mean if all things remain constant and lower the weight the numbers will be higher and vice versa?

 

[Begle1]

:redx:

Umm, which is faster to 100mph...a 500hp 3000lb car or a 500hp 12,000 car???

If the rollers on a Mustang dyno weigh 3000lbs a 500hp truck that weighs 7100lbs on the street will obviously spin the 3000lb rollers to 100mph FASTER than a car that weighs 3000lbs. The computer on the dyno needs to calculate HP based upon real world weights and the vehicles ability to spin the XXXXlb rollers.

As long as the dyno knows the weight of its drum and how fast it was accelerated, what does the weight of the vehicle have anything to do with it?

I don't see how putting a ton of concrete in the back of my truck is going to cause me to spin rollers at a different acceleration? Unless we're having slippage issues?

 

[oldsmokey]

As long as the dyno knows the weight of its drum and how fast it was accelerated, what does the weight of the vehicle have anything to do with it?

I don't see how putting a ton of concrete in the back of my truck is going to cause me to spin rollers at a different acceleration? Unless we're having slippage issues?

I was thinking the same thing i dont really see the reason for entering the weight factor either. Thats why I wonder if you change the weight or have the wrong weight the numbers would be off.

 

[nwpadmax]

As long as the dyno knows the weight of its drum and how fast it was accelerated, what does the weight of the vehicle have anything to do with it?

I don't see how putting a ton of concrete in the back of my truck is going to cause me to spin rollers at a different acceleration? Unless we're having slippage issues?

That's easy.

Inertia dynos are based on using math to equate the acceleration of the rotating mass of the drum with the acceleration of a car of X weight in a straight line. It's an estimation technique because you're not measuring torque directly, but coming at it though equations based on horsepower.

I can see where if you had a drum much lighter than the car, then you would probably need to know the relative weights more accurately. If you made the drum heavy enough, its own inertia more accurately matches that of most cars and the approximation is "good enough".

DynoJet has a technical writeup of how they do the math.

Remember, the inertia dyno was invented to be a low-cost alternative to the much more complicated load cell units (eddy current absorber, water brake, etc.). The repeatability from run to run is usually very good because there are far fewer parts and not many operator controls.

 

[Burner]

do all dynos require the weight of the truck to be put into the computer before a dyno pull?

No

3k or 5k wheels....... the Inertia Dyno reads how fast you move "X" (the drums) from point A to point B. The drums ARE the mass.

To keep it simple no, not all dynos require weight of test car/truck.

 

[Loud&Obnoxious]

I may be wrong but I believe it is more for tuning the engine for real world conditions. The dyno loads the rollers to make the vehicle perform as it would on the street, its not just for measuring hp and tq.

 

[Tate]

Wouldn't the weight only need to be known if you are doing 1/4 mile simulations on the dyno?

 

[Glasseater]

I may be wrong but I believe it is more for tuning the engine for real world conditions. The dyno loads the rollers to make the vehicle perform as it would on the street, its not just for measuring hp and tq.

some dynos don't have the capability to put a load on the rollers, an inertia dyno is the example of this

 

[Begle1]

True or false:

1. An inertia dyno measures horsepower by timing the acceleration of a drum of a known mass.

2. An inertia dyno calculates torque through a function of horsepower and engine RPM.

3. Inertia dynos not designed for really high torque engines often have trouble placing enough load on the engine for the engine to produce full power before it reaches full RPM.

4. Inertia dynos have some way to place an additional load on the drums, to better test high-torque vehicles.

5. The vehicle's weight input would have to do with the additional loading that dynos do to better test high torque engines.

 

[oldsmokey]

Wouldn't the weight only need to be known if you are doing 1/4 mile simulations on the dyno?

Thats the same question that I asked but was told that changing the weight would change the results.

 

[Burner]

Man, you folks need to THINK about your questions...... LOAD dyno's and Inertia Dyno's are two different animals. The difference between the two is more than the difference between a gas motor and a Diesel motor.

Look, on an Inertia Dyno it doesn't matter how much the dang truck weighs. Look at our trucks...... same year GM truck comes in 2wd, 4wd, sb, lb, cc, ex cab, auto, stick and different tire sizes but they ALL have the same motor even though the weights are different. Other than the parasitic drag from dually tires, larger tires, longer drive lines or 4x4 transfer cases it's going to read the same HP. Use an Inertia Dyno and get a standard truck and do the HP, then put 1,000 lbs in the bed...ya know what, you'll get the SAME HP number, the same.....

A LOAD Dyno can do everything an Inertia can but it can ADD LOAD or resistance to the wheel. Then again, they cannot "tell" you 1/4 mile times, only a guess. Real times are made where?....at the track. It's not all about the motor, it's about set-up and the driver too.



....If you don't understand the difference, go READ up on the subject. And no, not on a forum. Go look it up in a Dictionary or something.:doh:

 

[Glasseater]

Man, you folks need to THINK about your questions...... LOAD dyno's and Inertia Dyno's are two different animals. The difference between the two is more than the difference between a gas motor and a Diesel motor.

Look, on an Inertia Dyno it doesn't matter how much the dang truck weighs. Look at our trucks...... same year GM truck comes in 2wd, 4wd, sb, lb, cc, ex cab, auto, stick and different tire sizes but they ALL have the same motor even though the weights are different. Other than the parasitic drag from dually tires, larger tires, longer drive lines or 4x4 transfer cases it's going to read the same HP. Use an Inertia Dyno and get a standard truck and do the HP, then put 1,000 lbs in the bed...ya know what, you'll get the SAME HP number, the same.....

A LOAD Dyno can do everything an Inertia can but it can ADD LOAD or resistance to the wheel. Then again, they cannot "tell" you 1/4 mile times, only a guess. Real times are made where?....at the track. It's not all about the motor, it's about set-up and the driver too.



....If you don't understand the difference, go READ up on the subject. And no, not on a forum. Go look it up in a Dictionary or something.:doh:

exactly, weight input has nothing to do with it

 

[Begle1]

Why do you hear about some inertia dynos not sufficiently loading down trucks to build horsepower? About dynos not being "set-up right" for Diesel's?

Is there any kind of set-up there? Auxiliary loading or otherwise?

Or is building boost with your brakes and then letting it fly really the best way to do it?

 

[oldsmokey]

exactly, weight input has nothing to do with it

Then why is it required with a mustang? I agree with you guys and the reason for the question. I dont think weight input has to do with it but I dont understand why its needed with a mustang.

 

[oldsmokey]

Man, you folks need to THINK about your questions...... LOAD dyno's and Inertia Dyno's are two different animals. The difference between the two is more than the difference between a gas motor and a Diesel motor.

Look, on an Inertia Dyno it doesn't matter how much the dang truck weighs. Look at our trucks...... same year GM truck comes in 2wd, 4wd, sb, lb, cc, ex cab, auto, stick and different tire sizes but they ALL have the same motor even though the weights are different. Other than the parasitic drag from dually tires, larger tires, longer drive lines or 4x4 transfer cases it's going to read the same HP. Use an Inertia Dyno and get a standard truck and do the HP, then put 1,000 lbs in the bed...ya know what, you'll get the SAME HP number, the same.....

A LOAD Dyno can do everything an Inertia can but it can ADD LOAD or resistance to the wheel. Then again, they cannot "tell" you 1/4 mile times, only a guess. Real times are made where?....at the track. It's not all about the motor, it's about set-up and the driver too.



....If you don't understand the difference, go READ up on the subject. And no, not on a forum. Go look it up in a Dictionary or something.:doh:

I didnt mention anything about an inertia dyno only why is a weight input needed with a mustang.

 

[Burner]

:bang:bang:bang:bang:bang:bang:bang









Sometimes ya just can't fix stupid........:doh: I give up.

 

[oldsmokey]

If im so stupid then why is it a requirment on mustang dynos. I understand the difference between load and inertia dynos. You keep saying there is a difference no sh#t. You spout off and say were stupid but yet you, the all knowing, has no answer to why weight is a required input.