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2017 Ski-Doo 850 E-TEC

The latest in 2-stroke technology tops 170hp on the dyno
2017 Ski-Doo Renegade X 850 E-TEC
Ski-Doo engineers claim the new 850 E-TEC will not have a decrease in oil or fuel efficiency, stating the 850 will see the same as the 800R E-TEC.
Kort Duce photo
The snowmobile world recently saw two of the most technologically advanced snowmobile engines ever built released in the same model year. AmSnow already put the Yamaha Sidewinder’s Genesis 998cc 4-stroke on a dyno, but DynoTech Research was equally excited to see what the new 850cc direct-injected 2-stroke E-TEC motor from Ski-Doo and Rotax would do. We were not disappointed!
2017 Ski-Doo 850 E-TEC engine front
2017 Ski-Doo 850 E-TEC engine back
Hot digits!
We wanted the numbers, and dyno testing this 850 E-TEC demo sled at DynoTech Research (DTR) was great fun! The Ski-Doo marketing people had teased us by suggesting that the new 850 E-TEC tested at “165 uncorrected HP” on their engine dyno. But was that test done in air temps of 20 F or 80 F?

Just for fun, DTR owner Jim Czekala checked Wikipedia, and that site suggests the Bombardier dyno facility is at an altitude of 1,100 feet (DTR’s dyno sits at 900 feet), but the STP correction factor (estimated HP that would be made at sea level in 60 F dry air) varies greatly with intake air temperature.

The only way to find out was to have Tom Ferry of Arctic Adventures grab an 850 E-TEC demo pre-production sled and bring it to DTR for a secret dyno session.
Fortunately, as we had hoped, the “broken-in” 850 sled they had (which has a 6% larger engine than the former 800) gulped 6% more uncorrected airflow (287 CFM vs 266 CFM). This translated into 6% more CHP (170hp vs. 160). The math was good, and we were happy! On a warm day at DTR headquarters in Batavia, N.Y., the 850 E-TEC made 160 actual uncorrected HP, which corrected “up” to just over 170 STP HP. We’ve used the same correction factor with DTR’s SuperFlow engine dyno for nearly 30 years.

Unfortunately, the new BUDS system (thanks to Jim from Cooper’s Sales and Service) wasn’t yet up to date enough to communicate with the ECU of the new pre-production 850, so we couldn’t advance the timing to see if there was more HP left “on the table.” Some readers of the DTR website will remember that advancing the 2016 800 E-TEC’s timing by two degrees added 4 or more HP, and it would have been great to see what that same tweak would do to the 850. Another 5hp?

What does the future hold for the 850?
170 is great, but that timing advance (and other possible power-adding projects) will have to wait until production 850s get miles on them, and the aftermarket companies start testing their power-adding goodies. Stay tuned to for more results on this incredible new 850 2-stroke!
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