We’ve been waiting for this news for ages, and I’m sure many Polaris enthusiasts have been asking for it as well; when will Polaris have a 4-stroke engine (Polaris ProStar S4 Engine)? We have to go back to 2012 which was the last year of the 4-stroke engine at Polaris, at that time, there was a turbocharged version of about 130 HP and a naturally aspirated version of 80 HP. Although in the snowmobile, the 4-stroke engine was no longer in the Polaris line-up, it should be mentioned that the technology has been around for years in the off-road world, and several engines are available… Including a two-cylinder ProStar engine of 1000 CC…
The trail snowmobile market has evolved a lot in the last decade, a certain category of enthusiasts want peace of mind, not to worry about oil, smell, and also the reliability of a 4 stroke engine by design.
Polaris is back in 2023 with a 4-stroke bike that will take on a very large market share, mostly held by BRP with its 900 ACE. As usual, Polaris did not give us any figures on this new mill, but it is a 1000 CC two-cylinder 4-stroke ProStar. Used for many years in the off-road world, this system uses a dry oil pump system, with an external tank and an electronically controlled throttle. To ensure that power is delivered to the track, engineers continue with the P22 primary clutch.
The newcomer’s power output is estimated at between 90 and 95 horsepower, which plays directly into the same niche as its competitor the 900 ACE from BRP. For 2023, it will be possible to get the S4 in the Indy Adventure, Indy Adventure X2, Voyageur 146 and Titan Adventure 155.
Our test…
During our stay at West YellowStone, we tested this engine several times to make sure of its behavior and performance. It is important to mention that a naturally-aspirated four-stroke engine (without turbo) loses power at altitude, between 3 and 4 percent per 1000 feet. The city of West YellowStone is at about 6600 feet. So from the start, the engine loses between 18 and 20 % of power, which means that an engine developing 90 horsepower in Quebec, develops between 73 and 74 horsepower, and it decreases more and more as you go up…
The Polaris ProStar S4 Engine is not a revolution as such, but it is certainly one of the most anticipated among Polaris enthusiasts. Without a doubt, it delivers the goods for this niche, with a touring flavor. This engine provides a performance similar to the competition with some particularities.
On the acceleration side, you can feel the torque pounds at low revs, which offers a correct and relatively linear acceleration. The clutches are well calibrated and give good support to the horsepower. After a few kilometers, you can feel the ease with which the pounds of torque maintain a cruising speed. And when you push hard, its behavior shows the power, to reach speeds more than respectable…
It is important to underline the work done on the suspensions with the arrival of an extra weight at the front. Although heavier, its behavior remains agile, without requiring too much effort from the shoulders to drive. We tested the Indy Adventure, Indy Adventure X2 and the Voyageur 146, with the S4 engine, in the case of the first two, the behavior was very similar, with both a coupled rear suspension offering excellent handling. On the Voyageur side, we noticed better stability with more confidence in turns. The added weight keeps the skis on the ground when exiting a turn, improving the overall handling of the vehicle.
The Polaris ProStar S4 Engine offers a bit of vibration at low RPMs with a duller sound with a bit of vibration, this becomes less as the RPM increases.
Without a doubt, this new engine was eagerly awaited by fans, and it will certainly please many!
