Dyno Comparison....for what it's worth

[Sledroll]

All this math is beyond me , as I struggled to get my grade 12 diploma , only after going to summer school , for math.
But , what I have read is some of the magazines , speak of the turbo on the SW "kicking in" at about 6500 to 6700 !
Could this be why the dyno results only start at 6500 ?
What do you say about that ?

 

[kviper]

I will not argue this there are no equations for the reduction! Just like a track dyno or chasis dyno. Rpm of the output is not used that's how you get final power. Page 1,2 in the results is simply coming up throgh the RPM and running out of page room and continuing on the next page. I guarantee a Dyno operator does not have a multiplayer for every gear change, driver change or tire size and gear combo on a chasis Dyno for a car. The power is read at the out put and motor RPM is used to calculate HP. The power (torque) measured at the out put on a Apex is what it is!!! As MrSled said, the difference in the two sleds is real world!

 

[kviper]

By the way if you go to Dynotech and look at Apex #'s don't use the pre production 2011 runs as we know that's not production#'s!

 

[kviper]

Actually I should re phrase some things! There are reduction factor's how ever there's only been a couple that have used them that's why most to near all dyno sheets show torque#'s in the lower 80's. IN MY OPINION you can only use one RPM source not one for HP and a different one for Torque so if you use out put RPM an Apex would only come up 120's for HP #'s and actually thinking back in my many many conversations over the years (getting old) I may be incorrect on chasis dyno RPM source! But quite sure it's the same source for HP and Torque. Been many arguments on this over the years and I think most of it is just opinion's. Every dyno operator I've worked with though has said the same thing, don't get caught up in the number's just concentrate on gains! Line them up and I'll tell you which one is faster!

 

[Sasquatch]

All this math is beyond me , as I struggled to get my grade 12 diploma , only after going to summer school , for math.
But , what I have read is some of the magazines , speak of the turbo on the SW "kicking in" at about 6500 to 6700 !
Could this be why the dyno results only start at 6500 ?
What do you say about that ?

I probably agree!

 

[Sasquatch]

Ok, you're right and all of the data DTR publishes is wrong. Unbelievable.

I apologize for my remark earlier it just showed my frustration. The numbers are correct for engine crank torque and hp!

 

[Sasquatch]

Actually I should re phrase some things! There are reduction factor's how ever there's only been a couple that have used them that's why most to near all dyno sheets show torque#'s in the lower 80's. IN MY OPINION you can only use one RPM source not one for HP and a different one for Torque so if you use out put RPM an Apex would only come up 120's for HP #'s and actually thinking back in my many many conversations over the years (getting old) I may be incorrect on chasis dyno RPM source! But quite sure it's the same source for HP and Torque. Been many arguments on this over the years and I think most of it is just opinion's. Every dyno operator I've worked with though has said the same thing, don't get caught up in the number's just concentrate on gains! Line them up and I'll tell you which one is faster!

Look hp is a number based on torque. You cant change that because hp is a mathematically created number based on torque at a given rpm. The dyno spread sheet shows torque at engine speed. If you apply any gear reduction to that torque increases. You say that torque is based on clutch speed and it is so 10700 engine speed reduced by 1.23 = 8700 rpm, at this 8700 rpm the Apex engine produces 148 hp. You say it is though only making 72.9 torque at that clutch speed! That is impossible!

The math says at that clutch speed of 8700 72.9 torque the motor is only then making 120hp. I know this is wrong, you know this is wrong. Multiply this by 1.23 of which the clutch is doing and the torque climbs to 90 and hp to 148. Why this is lost on people I don't know but the dyno report shown on the first page shows 161 hp and torque just under a hundred. While the dyno is said to be wrong and out by 10 hp somehow it was also wrong and out by 20 pds of torque. Again impossible!

The numbers you are referring to are based on engine speed and for engine speed they are correct, to get clutch speed, numbers must be increased by 1.23 which is the ratio of the gear reducer. The numbers shown in the graph posted above are clutch speed and of course torque increases when a gear reduction is introduced. Put you car in low gear and torque increases by the % the output shaft speed is reduced from 1:1!

What you are missing though is if they do a dyno run using two different rpms one being output shaft (clutch) and the other being crank speed all numbers must be converted to one or the other. In the case of above picture graph they used clutch speed in the case of the graph you refer to they used crank speed. To get the dyno to show accurate numbers they had to reduce torque numbers from the output shaft by 1.23 to get the correct torque numbers at the crank. You say this can't be done but its easy to program and I quote from the DTR page showing that a simple math change can be added or subtracted.

"I went back and reviewed last years
F1100 test data. Sure enough, I found that the dyno was improperly programmed for 1/1
direct drive instead of 1.5/1 used for most sled engines. So if you go back to last year’s
test data and multiply each RPM step by 1.5 (and divide each torque reading by 1.5) you
will get identical torque and HP as shown here. The only difference is the precise friction
HP added by the dyno computer to compensate for the known HP loss from the very
efficient toothed belt drive. That friction HP compensator is only activated at 1.5/1, and
since the dyno was programmed improperly for 1/1 the HP lost to friction is not added
back in. Operator error! This is how I screwed up the first time we tested the DNE/ Gus
Bohne 700+ HP turbo—that time it was the opposite goof—the dyno computer was set at
1.5/1 while the monster engine was actually direct drive to the dyno. So when the engine
was spinning only 6500 RPM the dyno computer thought it was spinning 9750."



I'm not the sharpest knife in the drawer but I understand math and know anything can be proven or dis-proven by math as long as the numbers entered are correct. Entering incorrect engine torque numbers in place of correct clutch torque numbers quickly proves them to be wrong!

Numbers shown are crankshaft numbers not clutch numbers! Believe what you will but the Apex makes over 100 pds peak torque (102.7) by 2012 American Snowmobiler/DTR NY Shootout dyno certification, etc. Also I agree don't get to hung up on dyno reports as they are best used to show improvements. But lets say your right and I'm wrong. I'm very proud of my 72.9 pd torque 120 hp sled producing a 110 mph top speed staying with the 129hp 83.7 pd torque to 75 sled and then leaving it behind. Never mind the 250pd rider sled weight difference.

 

[Sasquatch]

The power (torque) measured at the out put on a Apex is what it is!!!

And you are correct. Output speed of 8700 and 148hp is 90 torque. It is what it is! This time your right! Math supports you!

 

[kviper]

Again not arguing your math. It's the theory. Another thing I learned after my second marriage is it doesn't pay to argue! LOL As long as I know where the power is made I can make my sled as fast as it can be no mater how the numbers are calculated. Agreed?

 

[MrSled]

Again not arguing your math. It's the theory. Another thing I learned after my second marriage is it doesn't pay to argue! LOL As long as I know where the power is made I can make my sled as fast as it can be no mater how the numbers are calculated. Agreed?

To me that's the only point in dynoing a sled.. is to find out where its sweet spot is and to establish a base line.

 

[snowbeast]

To me that's the only point in dynoing a sled.. is to find out where its sweet spot is and to establish a base line.

Bingo,now you can clutch for it.

 

[Sasquatch]

Again not arguing your math. It's the theory. Another thing I learned after my second marriage is it doesn't pay to argue! LOL As long as I know where the power is made I can make my sled as fast as it can be no mater how the numbers are calculated. Agreed?

Very true and I agree totally, dynos are a tool to show and make gains or losses. As we all know they become gospel and create much folklore and manhood wagging in the process. All dynos slightly differ from each other and as hard as they try to keep them (dyno's) tweaked to air temp and barometric pressure they still differ. Point being Hurricane has shown that a stock broken in Apex makes closer to the 160 that the pre 11 Apex dyno that everyone was pissed about showed. Course everyone was pissed about that too. Ive seen the dyno reports, I think I have most of them.

I was disputing the claim with little success it seems, that the Apex makes more then 73 pd torque and why! Theory and math go hand and hand one proves the other. I did not create the math or the theory I only used it as it was passed along! Funny thing is no one can disprove my conclusion of facts as I stated them, they only disbelieve them and say I'm wrong. Why? Cause of a dyno report. Somehow the dyno is important after all. LOL! Math never was my favorite class but it didn't take long to realize that without it performance in my favorite shop classes would suffer. I loved shop.

The sweet part about the 11 up Apex is you can be anywhere between 9700 and 11000 and the difference is 1 hp. The Nytro 8000 to 8400 but like all the Yamaha four strokes they will rev past that with little loss of power.

I'm still on my first wife of near 37 years but she is always right if I know what is good for me. Maybe that is why I'm still on my first wife and I argue here!

 

[kviper]

LOL on the wife part! I must have been a slower learner in that area, 21 years on second shot at it and there won't be a third!
We need the dyno to tune from but clutching still needs to be finalized in the real world!

 

[stevewithOCD]

I wish i was part of TTY before I got married!

 

[stevewithOCD]

SQUATCH: You may need to buy a wrist guard before you get metacarpal syndrome....lol...I guess that's better than a divorce. Every time you vent: we learn...at least those of us that listen!