Track speed vs Ground speed

[dvst8r]

Typically I hear track speed is everything, but I am a little confused or maybe I have it right but just need verification:

I have two sleds and these are the break downs:

-One makes ~170hp one makes ~140hp
-The 170hp one weighs about 570lbs ready to ride, the 140hp one weighs about 540lbs ready to ride.
-They both have 162" tracks, the 170hp one has 2.25 x 16, the 140hp one has 2.5" x 15 CE

On the same day on the same hill, with me riding each one, and the gps recording ground speed, and using the lie o meter to record track speed the 170hp sled will make 60-65mph track speed, and the 140hp sled will make 35-38mph track speed. However ground speed the 140hp sled will be almost 5mph quicker, and will out climb the 170hp sled. The only conditions I have not yet been able to try are spring conditions with extreme traction.

Now my question is why?

Is it setup, or skid design, or just that .25" extra lug depth and a bit better designed track?

 

[glassman]

It probably has alot to do with traction. Obviously the track is spinning more on one than the other, and maybe floating a little better too. The CE track is an outstanding performer in the pow, and seems to propel the sled better than alot of other tracks. Suspension set up will have alot to do with it as well. If one sled is trenching more than the other then it will naturally take more power to move it forward.

 

[maxwell]

bingo.....these are my findings with the 3" tracks. yes the trackspeeds are lower from the excess weight. but its actually making the ground speed that is on the speedo. where as the 2.5 or less competition is spinning those track speeds but not making the same ground speed.

 

[dvst8r]

This is kind of what I wanted to hear, as I have been debating putting a 3" on it, but wanted to make sure it would "solve" my issue.

 

[glassman]

I posted this elsewhere, but 2 pro rmk's side by side. One with the stock 163 x 2.4 , was showing 45-46 mph track speed on a relatively good powder day. (1 1/2 ft) Mine with the 162 x 3" was showing 38-39 mph track speed. We drag raced a few times up some decent hills and I could pass him pretty quickly. His definately was spinning more than mine, so traction is definately a factor. Like you said though, in more set up snow, it wont be as big of a difference.

 

[oler1234]

bingo.....these are my findings with the 3" tracks. yes the trackspeeds are lower from the excess weight. but its actually making the ground speed that is on the speedo. where as the 2.5 or less competition is spinning those track speeds but not making the same ground speed.

i can second this motion going from a 2.25 holey track to my 3" track