Top end MPH on 17 SW.

[scottt]

I have a 17 LTX LE 137 thats all stock except for a TD powertrail 250hp SM tune,dalton primary weights and B/O secondary spring. Temps or snow conditions for nice top end runs havent been that great. Last time out it was mid 30's and the snow was a little loose. Stopped at 2 different lakes for some top end runs. !st lake was a little loose and the speedo hit 120mph but Gps was only 112. 2nd lake was a little better and at 117-118 speedo was 115 gps. Pretty sure air temps and a tighter snow pack would help but still I was expecting closer to 120 gps. Boost read a pretty much stable 15.3 range and rpms averaged around 9000..Am I expecting too much for the air/snow conditions? Didnt know if my setup was unusually slower than it should be. Thanks

 

[Simplespeed]

What track and traction products ? What is your gearing ? What is your suspension set up? How much is your weight fully dressed? What octane are you running? What primary weight and spring? What is your clutch offset measurement? Have you ever blown a belt ?

 

[scottt]

Stock 1.25 track with studs up the middle. Stock gearing. Suspension is like factory specs. Probably 225 lb dressed. 91- 92 octane. Stock primary spring and the 1/2" long weight in the dalton arms. I asked for 58mm at the cat dealer and they said they got it but personally I don't know. At the beginning of the season ( and first time I've really rode it) it did blow a belt at about 50 mph at wot for about 2 seconds. Since then I've replaced the belt with a new 8dn belt and has been fine since. It does squeal now and then idling after riding it some Since blowing the belt. My first season with this sled so I really don't know what it's been through. I put a new dmc 21 tooth and bop driveshaft saver as preventive maintenance. It was untouched from the factory in there.Had to get the driveshaft bearing replacement kit as the damage from the factory bearing already messed up the driveshaft.

 

[earthling]

All the power in the world won't allow you to out run the limits of your gearing. It may help you find those limits faster.
There is a lot more to speed than just HP. What RPM are you turning. That will tell you where you are in gross terms with clutching. Then you have to pay attention to a lot of little details. You shouldn't expect to outrun the gearing and stock, you are 21/41 gears so about 124MPH with overdrive. That would be on great ice, you are in the ballpark probably for your conditions. Make sure the rest of your sled is setup right, there are a ton of resources and comments made by guys who are really fast on this site. Try a couple of searches, lots of information to dig out.

 

[scottt]

Yes I agree...just read where some stock SW's were running more mph than I am. I'm new to SW's so just asking what you guys thought.

 

[74Nitro]

I have GPS'd 126 with slightly heavier stock weights and MS16 on a 19 SRX. Good conditions but not perfect.
But the SRX is lower with one inch track.
You should be able to break over 120 GPS for sure with 250hp.

 

[Simplespeed]

The reason why I asked if you blew a belt is sometimes this tells me your clutching is off or more importantly your center to center and or offset is off.. Blowing belts can effect both. Now that you stated you have a squeal its mostly likely out to lunch so to speak… You also probably need to work on suspension set up and get your sled on good hard pack to find your true mph.. Loose snow, with short studs will not mph with a so so suspension set up… Also boost leaks will hurt your power….

 

[scottt]

The reason why I asked if you blew a belt is sometimes this tells me your clutching is off or more importantly your center to center and or offset is off.. Blowing belts can effect both. Now that you stated you have a squeal its mostly likely out to lunch so to speak… You also probably need to work on suspension set up and get your sled on good hard pack to find your true mph.. Loose snow, with short studs will not mph with a so so suspension set up… Also boost leaks will hurt your power….

If it seemed to stay over 15 psi the whole time at wot would that indicate it doesn't have any leaks?

Maybe if the conditions were pretty close to perfect I could gps another 5 mph to reach 120. I haven't had the sled long enough for those ideal conditions. I just thought it should of been better than 115 the other day. 9000 rpm seemed to be where it wants to be? I'm far from being knowledgeable on any of this stuff. This summer I could dive in some and check out some of the clutching and clearances .I do have semi aggressive snow trackers on the skis too.

 

[0degC]

I have a 17 LTX LE 137 thats all stock except for a TD powertrail 250hp SM tune,dalton primary weights and B/O secondary spring. Temps or snow conditions for nice top end runs havent been that great. Last time out it was mid 30's and the snow was a little loose. Stopped at 2 different lakes for some top end runs. !st lake was a little loose and the speedo hit 120mph but Gps was only 112. 2nd lake was a little better and at 117-118 speedo was 115 gps. Pretty sure air temps and a tighter snow pack would help but still I was expecting closer to 120 gps. Boost read a pretty much stable 15.3 range and rpms averaged around 9000..Am I expecting too much for the air/snow conditions? Didnt know if my setup was unusually slower than it should be. Thanks

Since you added 50hp I would gear it up, just a bit. Then get on some hard pack and try again.

 

[fourload]

I have the same tune on mine but I run stock weights with a thunder orange sec spring and a dalton 35/39 helix.I also run a XS belt. I weigh 230 and mine is studded up the middle with 1.45 gold diggers. I have seen 122gps 127 speedo in really good conditions on our lake. Most of the time in looser snow I can run up to around 120 on the speedo. Conditions and temps mean a lot. I also hold 15.3 psi for my runs most of the time. Good enough to run away from any sled around here except a few higher tuned Winders . You said you run a DN belt? These are a little longer and will run a couple of mph slower.

 

[jonlafon1]

If it seemed to stay over 15 psi the whole time at wot would that indicate it doesn't have any leaks?

Means nothing.. Boost leak test is the only way to know if its leaking.. Guessing if its never been leak tested then you have some spots that leak.. Nothing you did wrong just age, miles, heat cycled clamps.

 

[Simplespeed]

I have the same sled and mine ran strong but lacked mid range so the changes made were, boost leaks eliminated, clutch off set changed to 59.5 , a updated helix, spring and shock changes to all suspension settings, clutches were checked and balanced, rollers replaced , primary weights worked on… Also worked on rear transfer rod along with shock to get sled to launch forward and get rid of ski lift.

 

[Simplespeed]

I have the same tune on mine but I run stock weights with a thunder orange sec spring and a dalton 35/39 helix.I also run a XS belt. I weigh 230 and mine is studded up the middle with 1.45 gold diggers. I have seen 122gps 127 speedo in really good conditions on our lake. Most of the time in looser snow I can run up to around 120 on the speedo. Conditions and temps mean a lot. I also hold 15.3 psi for my runs most of the time. Good enough to run away from any sled around here except a few higher tuned Winders . You said you run a DN belt? These are a little longer and will run a couple of mph slower.

You running 1.45 studs on a 1 1/4” Rip Saw or you running a 1” track ? Your top end should be faster if your running 1” track….

 

[scottt]

Means nothing.. Boost leak test is the only way to know if its leaking.. Guessing if its never been leak tested then you have some spots that leak.. Nothing you did wrong just age, miles, heat cycled clamps.

I'm pretty sure it's never been tested...was bone stock when I got it,,,didn't even have some of the more critical preventive maintenance things done. Has 5100 miles on it now. I put the tune on it after I bought it but before I rode it so I don't even know what to expect from a stock SW. I get no ski lift when going wot..just a strong pull on the handle bars. It does seem to nosedive alot when you get off the throttle at the end of a 115 mph run...so much different than my apex was.
The SW still has its original 1.25" track.

 

[earthling]

I'm pretty sure it's never been tested...was bone stock when I got it,,,didn't even have some of the more critical preventive maintenance things done. Has 5100 miles on it now. I put the tune on it after I bought it but before I rode it so I don't even know what to expect from a stock SW. I get no ski lift when going wot..just a strong pull on the handle bars. It does seem to nosedive alot when you get off the throttle at the end of a 115 mph run...so much different than my apex was.
The SW still has its original 1.25" track.

You may be do for a shock rebuild, sounds like a front spring in the skid as well.