Shoot Out Results For XTX>>>>>>>

[**sj**]

rotating mass is a far lesser tax than the inefficiency of the 121 compared to the 144.. should I say the better efficency of the 144...

the analogy of standard rotating mass as in a crankshaft or balanced item doesnt apply IMHO since you are dealing with a non balanced ...non precision movement with intermittent mechanical friction...

 

[rxrider]

It's a Apex XTX and sorry but the 128 is faster on the big end. Put them on the hard pack and the 128 will win.

Larry

Around here the XTX is pulling higher MPH than the 128 so far, sled have 300+ miles on them or 500 kms. My friends at the dealership ride both sleds.

Jan-O
rxrider

 

[grader]

another way to think about track rpm, at any given speed the longer track is turning a lower rpm.

 

[Dano]

another way to think about track rpm, at any given speed the longer track is turning a lower rpm.

Made me think twice on that one. Tracks go same RPM as they have same pitch. If driven from the centre, then that would hold true. Questionable rolling resistance difference between the 2 is the question.

Dan

 

[jaydaniels]

another way to think about track rpm, at any given speed the longer track is turning a lower rpm.

Made me think twice on that one. Tracks go same RPM as they have same pitch. If driven from the centre, then that would hold true. Questionable rolling resistance difference between the 2 is the question.

Dan

Yeah, I had to think twice on this as well. I don't think its so much RPM rather track speed. It will take more time for the longer tack to make one revolution but its traveling at the same speed and that is what determines the speed you are travelling.

 

[fourload]

A 144 inch track spins about 12% slower than the 128 incher at the same speed. However the 144 incher weighs about 8 lbs more. The rotational energy at a given speed for both tracks is virtually the same for both tracks. The 144 has about a 1% edge in the effiency dept if my rotational energy formulas from college were calculated right. The 144 wins in traction and looks like it has a more efficient approach angle. On paper the 144 looks quicker and faster unless the gearing is slowing it down on the top end!!!

 

[kviper]

The XTX skid is more efficient for two main reason's, Flatter approach angle and the tipped up rail does not make the stud's or track lug's have to break loose to make the bend around the rear wheel's due to it being off the ground, As Mike Knapp stated.

 

[Dano]

A 144 inch track spins about 12% slower than the 128 incher at the same speed. However the 144 incher weighs about 8 lbs more. The rotational energy at a given speed for both tracks is virtually the same for both tracks. The 144 has about a 1% edge in the effiency dept if my rotational energy formulas from college were calculated right. The 144 wins in traction and looks like it has a more efficient approach angle. On paper the 144 looks quicker and faster unless the gearing is slowing it down on the top end!!!

Your drivers are spinning the track at the same spot at the same pitch in either track length, therefore you can theoretically have a mile of track behind you and spin the same RPM for the same speed for any other track. You can’t convert the thought of a center driven circle such as a tire, into a theoretically round snowmobile track when you power the circle at the side as appose to the centre.... Of course, clutch and gearing changes are often needed when adding rotating weight and resistance when driven with the same hp at engine crank. None of the Apex’s have the power to max out the gears and fully shift out the clutches at peak rpm or else we would be seeing speeds of 125-135 mph. However, to find the best mechanical advantage in gear, drivers and clutch combos is the million dollar question.
Sorry, don't want to come across as "lazybastard" lol

Dan

 

[**sj**]

The XTX skid is more efficient for two main reason's, Flatter approach angle and the tipped up rail does not make the stud's or track lug's have to break loose to make the bend around the rear wheel's due to it being off the ground, As Mike Knapp stated.

we all know this was true with the previous years...but look at the se's skid and the xtx...approach angle ...well someone might need to look closer....

also the rear lugs breaking loose theory would seem to only be a factor in deep snow...glare ice wouldnt have the same affect..

that said the tipped up rail might "precurve" the rotational energy...

 

[kviper]

The XTX skid is more efficient for two main reason's, Flatter approach angle and the tipped up rail does not make the stud's or track lug's have to break loose to make the bend around the rear wheel's due to it being off the ground, As Mike Knapp stated.

we all know this was true with the previous years...but look at the se's skid and the xtx...approach angle ...well someone might need to look closer....

also the rear lugs breaking loose theory would seem to only be a factor in deep snow...glare ice wouldnt have the same affect..

that said the tipped up rail might "precurve" the rotational energy...

Drive the two skid's on smooth bare ice and take a close look at the stud mark's, You will see what i am talking about. Bigger rear wheel's would have some benefit in this case scenario as it would pitch the stud's/lug's at a slower rate away from the ice. You can also take note to the amount of ice chip spray from the two skid's when just rolling by.

 

[KnappAttack]

kviper is correct that the tipped rails allow studs to pull out of the ice prior to making the corner. This frees up power. If you don't stud, it still allows the track to pull up off the groomed trail also freeing up power. You're not chunking out ice or snow out of the way. It's an old drag and speed run trick I used to employ. I'd machine the rear wheels smaller and slot the rails to bring the wheels way off the ice, I'd then machine the hyfax at an angle much like the tipped rail being used in the XTX. We would always pickup a few MPH by doing this. Everyone else would add big wheels and ride on the wheels thinking they were more efficient using the larger dia. We just laughed at these guys. I would make mine smaller and always go faster thru extensive testing on the timers and radar.

8 pounds rotational mass with the track has minimal effect on acceleration.

I have testing data to confirm this. I took just over 8 pound of rotating mass off my pro-stock 800 sled by using titanium cleats and studs in lieu of steel. Using the same traction pattern and amount of studs on two identical tracks. Made three runs on the heavy track, and three runs with a track being just over 8 pound lighter on my 800 pro-stock. Net gain in ET was nothing!!! The sled did not even pickup one-hundredth of a second. Spent over a thousand dollars to shave off 8 pounds of rotating mass to gain nothing.

So much for 1 pound of rotating mass being equal to 7 pound of static weight in a snowmobile track. Myth busted!

 

[bottlerocket]

Wow Im shocked the weight lose of any kind for that matter didnt gain. $1000.00 for the test is pricey and thanks for the info. You should sell the info to recoup....

 

[**sj**]

rotating mass is a far lesser tax than the inefficiency of the 121 compared to the 144.. should I say the better efficency of the 144...

the analogy of standard rotating mass as in a crankshaft or balanced item doesnt apply IMHO since you are dealing with a non balanced ...non precision movement with intermittent mechanical friction...

maybe without the credentials and money investment...but I think this is what I said...lol

 

[rxrider]

Another thing to thing about, the track is pulled around by the drivers, not pushed... the upper part of the track is under tension the lower part has less tension to it. Thus the angle where the track passes over the upper rear idlers inside the tunnel will play a big part in the equation. A longer skid will have less angle past this point than a shortie....

Any comments on my theory is highly appreciated