Gearing up a turbo 800 pro

[briand]

Bringing this back to get any updated responses if any. Was originally posted in September 2015.


Just wondering here how everyone is gearing there turbo. Right now mine is stock gearing but have read a lot that some are gearing there's up rather then down. I have given serious thought to this as well for this year and would like to here from those that have geared up how they like it . Thinking of using 1.85 to 1.95 ratio. Hows belt heat? Did it increase track speed? if so by how much. Overall are you satisfied?
It just seems to me that if you found the best ratio before turbo and say it was around 2.15-2.26 range with a turbo you would need to increase the ratio to a 1.85 - 1.90 for the power difference you have now to get the best clutch efficiency. Any thoughts to this.

 

[Spaarky]

One of the best Tsleds I have ever rode was geared 1.75:1. I always ran 1.85:1. I am a little bigger guy, so that is how we set up mine. It was good for all around riding. It has to work with clutching to make it work though.

The trend is to a bit lower gearing. I think Burandt is running around a 2.25:1. Some of the guys are running almost the same as stock NA sleds. It comes down to personal preference.

 

[briand]

One of the best Tsleds I have ever rode was geared 1.75:1. I always ran 1.85:1. I am a little bigger guy, so that is how we set up mine. It was good for all around riding. It has to work with clutching to make it work though.

The trend is to a bit lower gearing. I think Burandt is running around a 2.25:1. Some of the guys are running almost the same as stock NA sleds. It comes down to personal preference.

No question about re clutching. IT's always fun to tinker with a new setup for me anyways. Have lots of secondary springs and a fair selection of helixes to try with it.

 

[phatty]

I went to 2.25 on mine (TKI belt drive/gears)
I also went to 7 tooth 3" drivers with the 2.5 CE track. Ridiculous hook up. Was a very noticeable and good difference from buddies turbos with stock gearing. Highly recommend it.

 

[wellfed777]

phatty

do you mean your final ratio of 2.25 includes driver change ?
also what CE 2.5 the 9174 ?

thanks

 

[B&M Fabrications]

One of the best Tsleds I have ever rode was geared 1.75:1. I always ran 1.85:1. I am a little bigger guy, so that is how we set up mine. It was good for all around riding. It has to work with clutching to make it work though.

This intrigues me... Seems logical though, taller final drive will load the engine harder and make the turbo spool differently. We may have to play with this type of setup this year.

 

[mountainhorse]

comparative ratio

phatty

do you mean your final ratio of 2.25 includes driver change ?
also what CE 2.5 the 9174 ?

thanks

2.25 on his TKI belt drive... PLUS the driver change give a COMPARATIVE ratio of 2.44:1 (compared to a stock 8 tooth driver)

 

[phatty]

2.25 on his TKI belt drive... PLUS the driver change give a COMPARATIVE ratio of 2.44:1 (compared to a stock 8 tooth driver)

Correct, and yes I ran the 9174 track.

 

[Spaarky]

This intrigues me... Seems logical though, taller final drive will load the engine harder and make the turbo spool differently. We may have to play with this type of setup this year.

We always ended up around stock weight, if you can believe that. Once we got the weight down, we had to add more fuel on the bottom.

The sled was a 2000 700 rmk. It flat ripped. That sled had every back yard builder trick in the book. Now it has another cylinder.

If you need more specifics, I can help out.

 

[briand]

This intrigues me... Seems logical though, taller final drive will load the engine harder and make the turbo spool differently. We may have to play with this type of setup this year.

Is it because its loading the tubo more or is it because your getting more into the clutch ratio we need with turbos (my own speculation here) or both. interesting thought.

Here's my thinking hopefully i can explain it here.

For me i always tried to setup gear ratio and clutching for maximum land speed and track speed while climbing or playing around in the powder. at about what i think is 1 to 1 shift out. Usually that was at about 3/4" from the top of primary. this is what seemed to be the best for me when i was stock. ( maybe its still not 1 to 1 but that's what i found to work the best) I Had the stock gear ratio, think its 2.1 with 20/42 gears. With lower gears could have got the belt a little higher in primary but i was happy with the stock ratio. Was getting around max of 45-46 mph track speed in 1.5 to 2 ft of powder.
Now with the turbo at 12 # at 7500 ft and peaks track 163" X 2.5" i am at about .5 inches to the top of primary track speed is close to 58-60 mph but now it seems the primary has lost some of its performance. Seem to be a bit lazy shifting out past about 55 mph. I think with the heavy load of climbing and deep snow the primary cant shift as efficiently past 3/4" to the top of primary. I feel if you increase the ratio say to about 1.95 you will get this ratio in the primary back to about 3/4" and maybe a increase in maximum track speed a few MPH.

Think about it this way to, when my stock pro puts out roughly 150hp sea level, at 10000 ft my power is at say 105 hp 30% loss. Now with a turbo say power is at 210 hp at sea level, at 10000 ft your still getting what 200hp. How can the low ratio for 105 hp sled at 10000 feet work the best for a 200 hp sled at 10000 ft?
Seems to me we are leaving a lot out on the table here.

Anyways this is my thoughts let's hear yours.

 

[B&M Fabrications]

Pretty much the logic behind it. Im going to start with stock gearing on my turbo axys and go up from there. Our turbo pro runs stock gear and is in the 60 to 65 mph track speeds but it's like you said...seems to be about maxxed there on the primary. The harder you load an engine the more heat it makes and heat drives the turbo as well as making the pipe hot.

 

[briand]

Just bringing this back up to the top. Anyone else want to comment now that some might be riding or getting close?

 

[briand]

TTT

Ok due to work and lack of snow during times this winter that i could have got away to mountains i have not been able to try the gearing up ratio i wanted to do. Just would like to here from others that might have how did it work for you? Notice any difference? I still hope to try this and hopefully this turns out well.

 

[mcfly13]

My question would be wont you create more clutch heat in belt slippage
Guess it really depends on where you ride
On and off through the trees veered way up is going to create clutching issues

 

[briand]

My question would be wont you create more clutch heat in belt slippage
Guess it really depends on where you ride
On and off through the trees veered way up is going to create clutching issues

Yes I think it will create a little more heat. For tree riding on and off the throttle I doubt this would work but the type of riding I do I think heat build up would not be a issue.

 

[black z]

How you want to ride the sled is going to determine the gearing. Personally I plan to gear down slightly, but I like more technical tree riding and slower speed stuff. If I was a chute climber I would definitely experiment with gearing up.

 

[briand]

Well today I ended up gearing my turbo pro up to 1.90 (20 - 38) from 2.10 (20-42)
Cant say how it will work up high in the steep and deep but down low at home here it definitely pulls a lot harder. did some testing here and found i had to remove about a 1 gram and switch out the black purple ( 160-240) secondary spring to a black white (160 - 260) team spring to get my rpms back. now it's spot on again at 8400-8500 rpm. sled pulls a lot harder and longer. Before I saw it from 20 to 60-65 then the pull would start to taper a bit but now it pulls harder in the 20 to about 73 mph zone before it tapers down a bit. I did not see any increase in belt heat but then again not up high in deep stuff either. checked and adjusted belt deflection to the min and it starts out the same as it did before. Very impressed so far and now just waiting to see how it preforms up high.

Like I said in a post above I don't think this will work for boondocking in the trees but for hill climbing might be worth a try.