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Discussion Starter #1
After I got my baseline hp number for the teryx exhaust test, I got to playing around with the dyno and I was thinking about how someone might screw with the dyno numbers to make their part do better so I just put 20% of a load with the load control and guess what the number jumped up two or three HP.

See a dyno measures torque and then mathematically converts it to HP.

You usually get the highest numbers where the engine is doing the most work therefore if you put a load on it, it does more work therefore the number goes up.

This is just one of many ways to manipulate numbers.

The following are a few more ways to manipulate the numbers:

Change to smooth tires between runs

Change to smaller tires between runs

Add more tire pressure

Change the correction factor in the dyno software between runs.

Loosen or tighten the tie down straps on vehicle.

Point is, take dyno numbers with a grain of salt unless you know for sure you can trust the person running it.

One promise I have made is to never manipulate numbers and keep comparisons fair as they can be and then let the chips fall where they may.

Trust me we would have a few more performance products for UTV's if I trusted the manufacturers. Since we bought our own dyno we found out more what didn't work than what does.
 

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Uh..Ohh.. Discussions like these may mean bad news for something or somebody(?):) We have faith and know the truth is out there!!
 

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Discussion Starter #4
Take a note, HW does not sell air intakes, exhaust and clutch kits for the Rhino 660 or 700 for that matter. The clutch kits for a rhino won't work and the intake and exhaust only work on a highly modified engine, they are pure waste on a stock engine.

Todd
 

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This is why I don't use a dyno for all my R&D work. Until you put it on the ground, run it around a track,up a dune or down the drag strip you don't know if a cam,porting,pipe,carb or compression ratio did any good or not. You may get big peak numbers on the dyno from one pipe but on the track your lap time go down. How quick it pulls out of the corners and off the line is the real test. Again I'm not downing anyone or dyno's for that matter it's just not the final answer.
 

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dynos are nice for a baseline and a/f reading,but like mickey said the real test is on the track
 

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After hearing Mickey & Todd, I come away with the feeling that the dyno is an excellent tool for comparing performance products if you can maintain the same levels for all the other variables while you're testing so you're comparing apples to apples.....hence the need for honesty. Then when you've sorted out & determined the top several products you find a track or dune or whatever & see if what you have really is the big improvement you think it is. And yes, with all the variables in a racing situation the best or fastest may not win. At least with Mickey & Todd doing all the work & having all the investment, we don't have to. Thanks again guys for sharing.:wave:
 

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Discussion Starter #9
FST,

I can see that but let me ask you something.

Explain this?

The dyno measures torque by measuring how quick the vehicle on the dyno accelerates the drum compared to RPM.

From my point of view, if one product on the engine spins up the drum quicker than another then it will do the same thing on the track.

The dyno is dumb it just knows when something moves the drum at a faster rate than before and I can't see how something that makes it spin up slower would out perform on the track.

By the way, I am not arguing with you. If you can explain it to me then I am ahead.
 

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FST,

I can see that but let me ask you something.

Explain this?

The dyno measures torque by measuring how quick the vehicle on the dyno accelerates the drum compared to RPM.

From my point of view, if one product on the engine spins up the drum quicker than another then it will do the same thing on the track.

The dyno is dumb it just knows when something moves the drum at a faster rate than before and I can't see how something that makes it spin up slower would out perform on the track.

By the way, I am not arguing with you. If you can explain it to me then I am ahead.


I in no way think you are trying argue with me. Here is one thing that I had to learn, my 900's make alot of torque and good HP on the dyno, but the more torque you put down at first it will make it read higher HP on the chassis dyno. If my 900 and my 840 show the same HP on the chassis dyno the 840 will win the race in a drag. The 900 will come off the line the first 10 feet harder but the 840 will run it down and pass it. The simple fact that I had to learn is the torque will mess you up. I have always liked torque motors and love strokers but they have to be built with bigger valves and sometime bigger cams to run with or out run a smaller motor. The chassis dyno's just don't show everything with these CVT motors(in fact they mask what is really going on),hence the reason why I got both dyno's by the same company with the same 9" toroidal flow water brake absorber. Land & Sea didn't make them a year ago but now you can buy the same system I have for the Kawie V-twin motors, everyone should have one.
 

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Discussion Starter #11
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
 

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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.
 

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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
 

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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
 

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Discussion Starter #17
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.
 

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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.
 

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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
 
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