The dyno and the Teryx

[Hunterworks]

I think the common denominator is CVT. This is the exact reason I wanted to lock it out.

I have just been unsuccessful locking this one out and starting it.

I have thought about making a tool that once the engine is started and in gear I can push against the bearing where the electric brake rides and push it in until the belt gets where I want it thus locking it out.

Problem is right now, this exhaust shootout has been on hold long enough and with the fuel injected Teryx coming we got to move quickly and get ready for it.

Todd

[Thunderhawk]

Todd,

Not all dynos measure torque. I don't know what dyno you use, so I can't say how yours works.

Engine dynos are set-up with an absorber unit (typically a water brake) and a torque transducer. Engine dynos measure torque through the transducer, then calculate HP. An engine dyno can load an engine and hold RPM, which is necessary for engine develpoment and testing work.


The most common chassis dyno is the Dynojet, which is an inertia dyno. Inertia dynos measure the rate of acceleration of the drum, which allows them to figure HP. Then they calculate torque backwards. Inertia dynos have a fixed roller weight (inertia weight) which approximates the weight of a vehicle. For example, if the inertia weight on a particular dyno is 600 lbs, then any vehicle on that dyno is treated as if it weighed 600 lbs, regardless of the actual vehicle weight. Some chassis dynos have an additional eddy current absorber unit added to better duplicate the actual vehicle weight, but this absober will still not allow a chassis dyno to function effectively in place of an engine dyno for testing and development.

[Hunterworks]

I have a Dynojet with an eddy current absorber.

By the way all dynos measure torque and convert it to HP.

[Thunderhawk]

Todd,

I'm sorry, but you're wrong. Not all dynos measure torque. Inertia dynos cannot measure torque, as they are not equipped with with a strain gauge (which is the device that actually measures the torque). Inertia dynos simply measure the rate of acceleration of the roller, and calculate the rest.

This will likely explain things better than I ever could. This is from Dynojet's WinPEP7 software:

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 (HP) is equal to applying a 550 pound force through a distance of one foot in one second. In real terms, it would take one HP to raise a 550 pound weight up one foot in one second. So to measure horsepower, we need to know force (in pounds) and velocity (in feet per second). Our Dynojet inertia dynamometer measures power according to the terms just described. The dynamometer measures velocity by measuring the time it takes to rotate a heavy steel drum one turn. The dyno 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, (F)orce equals (M)ass times (A)cceleration. Power is coupled to the drum by friction developed between the driving tire of the vehicle and the knurled (diamond shaped) steel surface on the drum of the dynamometer.

Torque
When an object rotates around a point, the object’s 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 one foot radius, is pulled with 550 pounds of force, the resulting force 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 because 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.



Please don't misunderstand my position here. I didn't intend for my statements here to be argumentative. I was just contributing some facts on the function and operation of different dynos. When the public understands how these dynos function, they can better interpret the results that they are given.

Harry

[Hunterworks]

Want to hear something funny? I went to Dynojet in Las Vegas back in April to advanced dyno school and they told that about torque.

Another, by the way, I have a strain gauge on mine too.

I'm cool with you, I know you are not arguing.

[Dynoray]

Originally Posted by Hunterworks

Want to hear something funny? I went to Dynojet in Las Vegas back in April to advanced dyno school and they told that about torque.

Another, by the way, I have a strain gauge on mine too.

I'm cool with you, I know you are not arguing.

You are right on Hunter, and as Mickey said, with a chassis dyno and a CVT, anything that makes big torque/hp quick and at lower RPM will spike your chassis dyno numbers but show better numbers all the way through.
Take a hole shot modual for a Prairie, all it does is put the ignition timing back in from 0-8MPH but it shows gains from 0-80 MPH.
We have engine and chassis dynos, as does Mickey now. Before mickey had his we argued about how a chassis dyno wouldn't work with a CVT and before we had the engine dyno for the Kawies I argued with people as well, thinking if it showed more RWHP it had to be better, couldn't be further from the truth. Although chassis dyno can work well for getting jetting close, that's about all they will do with a CVT and if your chassis dyno loads it hard, you'll end up rich in the field, if it'loads it light you'll end up a little lean in the field.
Ray

[Hunterworks]

These are the reasons I normally lock the CVT out so it can't shift gears but with the clutch design on the Kawi this makes it nearly impossible.

Maybe I just don't know but I figure if it does not get to the ground then what good is the power, if it does then the chassis dyno will measure it.

[Four Stroke Tech]

Originally Posted by Dynoray

You are right on Hunter, and as Mickey said, with a chassis dyno and a CVT, anything that makes big torque/hp quick and at lower RPM will spike your chassis dyno numbers but show better numbers all the way through.
Take a hole shot modual for a Prairie, all it does is put the ignition timing back in from 0-8MPH but it shows gains from 0-80 MPH.
We have engine and chassis dynos, as does Mickey now. Before mickey had his we argued about how a chassis dyno wouldn't work with a CVT and before we had the engine dyno for the Kawies I argued with people as well, thinking if it showed more RWHP it had to be better, couldn't be further from the truth. Although chassis dyno can work well for getting jetting close, that's about all they will do with a CVT and if your chassis dyno loads it hard, you'll end up rich in the field, if it'loads it light you'll end up a little lean in the field.
Ray

We never argued about dynoing CVT motors, that is V-FORCE JOHN thing. I only disagree with you over inflated numbers. My butt dyno was always closer to the truth then your numbers and then VFJ backed that up on his dyno.

[Dynoray]

Originally Posted by Four Stroke Tech

We never argued about dynoing CVT motors, that is V-FORCE JOHN thing. I only disagree with you over inflated numbers. My butt dyno was always closer to the truth then your numbers and then VFJ backed that up on his dyno.

I think we did argue a bit, LOL But I argued with people years ago as well, when all the CVT experts told me not to pay any attention to what a chassis dyno said, I thought at that time "if if shows more RWHP then it has to be better" after it was proved to me and more testing of our own I found that was so far from right it wasn't funny and it's, for the most part, completely wrong as the good motors show good RWHP number but the great motors don't.
We give out real world numbers, what an engine actually makes, now yes it still has to be put to the ground but I think having our engines powering the quickest all motor Brutes, and V's and Teryx's in the world that we know of is a pretty good indication that our motors make what we say they do, LOL
Ray

[Hunterworks]

Dynoray,

What business do you own or work at?