There is no formula as per,because cvt calibration changes with actual hp output and different models will be different. Also with your turbo there will not be much change,because you are creating your own atmospheric pressure.
I had recently just answered sombody with a question about altitude and the effects on cvt calibration. I just found it and copied it here,it may help some understand the effects of altitude on a cvt:
Cvt clutch calibration is simply this:
..controlling the rate of shift of the belt.
First lets look at the effects of high elevation. As you know,as you go up there is less oxygen. Even if you have a EFI fuel injected model,..it will help correct the air/fuel ratio to maintain as much hp as possible...but ,no matter what,..there is less air up there..less air,and therefore to correct the mixture it compensated with less fuel. Less O2+less fuel = less hp plain and simple right.
A 750cc at 10,000 ft elev may only make the hp of a 500 cc at sea level on a good day.
As for the cvt belt system,remember you are controlling the "rate of shift " of the belt during acceleration. ANY time you change:
- total hp output(like mods or altitude),
-gearing(like bigger tires ot different final drive gears),
-PEAK hp rpm requirement(like racing camshafts),etc
..the cvt should be re-calibrated to acheive optimum performance.
And thus many snowmobile manufacturers offer the same engine package on many snowmobile models,but different cvt clutch calibration for the ones intended for high altitude applications.
For explanation sake,think of it sort of like a 10 speed bicycle maybe. If you have a very strong athlete on this bike,he may peddle easily up a long hill in a tall gear selection on the bike. ....if you put a weak sicly skinny kid on the bike he may need to move the chain up a couple gears on the rear sprocket to be able to get up the same hill .
Proper cvt calibration is sort of like that. You calibrate it to control the "rate of shift of the belt/pulley system)..to keep thew engine operating at the proper rpm zone where the engine makes peak hp.
If you are at a very high elevation ( less hp)....and for instance the peak operating rpm where that engine makes power is at 6000 rpm. ..If you are still calibrated to upshift as quickly as you can get away with at sea level,it may upshift the belt to too high of ratio for the available horsepower and will lower the operating rpm during the shift phase. The engine is now revving lower than the "best rpm" for the engine during acceleration....and your performance is suffering. You are now like the weak sickly kid on the bicycle going up the hill...you have less power,but you cannot shift to a lower ratio quickly or accurately enough(or hold the correct rpm) because you not driving a manual shift,and the cvt system is not calibrated properly for the available hp.Your weights may be still too heavy to actually shift back all the way to low ratio unless you let it roll out a long ways when coming to a stop.
At high elevations you actually do not want to upshift the system too fast,and put yourself in too high of belt ratio too soon,as it will labour your rpm and can actually cause slippage because you do not have the belt in the correct ratio for the situation.In high elev situations you need to upshift slower than you can get away with at lower elevation.
If it was a standard shift car and someone pulled one plug wire off and you had less hp you would need to stay in lower gears longer to climb a hill right?
The biggest difference in clutch kits for one vehicle is usually the flyweights. Some companies offer up to 8 different kits for each of the teryx and RZR models,big tires low,big tires high,mud tire,sand,etc.
Our Dalton clutch kit for the RZR is only one kit,it contains some optional primary springs for engagement preference,and a set of our patented "quick adjust" flyweights.The whole prifile,and shape of the weight needed changed from the typical polaris stuff we had on the shelf for snowmobiles or atv's,..but a case specific flyweight profile helped immensely with low end belt grip and lower belt temps in certain conditions,..This also allowed most efficient calibrations without needing to drive spring pressures too high in the secondary clutch .This package has a ton of flexibility.The quick adjust flyweights are also full width on top of the curve so they do not eat up rollers like some weights I have seen.
The nice thing about this kit is that you don't have to question whether you "bought the correct version",....or ...did I tell the guy the correct info?....what if I change my mods or tires???...as it is fully adjustable and the instructions in the kit show the various ,tested settings for the different tires, altitude, and application.
With these flyweights you dont even need to pull the clutch or remove the belt or take the weights out of the clutch at all to adjust them. You just turn the clutch and add or subtract from each flyweight while the weights are still in the clutch.
Some people only run big mud tires in the spring,and use stock size all summer,...and some people run at 2000 ft elevation most of the year,but make a trip for two weeks every year to the mountains. For people in tis situation they can easily recalibrate for their trip or tires without buying anything more....and someday they may purchase a big tire,or different applcation and you just adjust the kit according to the instruction sheet.
As with any Dalton kit,it comes with a 30 day satisfaction guarantee to the end user.
I'm just a hillbilly maybe,and I don't like getting into graphs and fancy terms when I'm trying to explain something to someone unfamiliar,but it is a bit of explanation of the reasons why altitude effects cvt system. I hope it helps a bit for your understanding.
Dale
Dalton Industries.
