Ski-Doo Designer Shares Secrets Of 850 Turbo R Water Injection System

EDITORS NOTE: Each year, a new season of Snow Goer magazine is kicked off with Q&A interviews with top factory snowmobile engineers, designers and product developer. The goal is to take snowmobile enthusiasts a couple of steps deeper into the design process and the minds of the people who created the new tech. As this story that was first published in the October 2023 issue of Snow Goer is being posted, we’ve editing interviews conducted in the last week on new-for-model-year 2025 technology. To see them on a timely basis, subscribe to Snow Goer today. In the meantime, enjoy this informative look at Ski-Doo’s water injection system on the 850 E-TEC Turbo R that was published last year.

TECH 2024: Inside Ski-Doo’s Revolutionary Water Injection System

Ski-Doo raised millions of eyebrows – in the snowmobile world and beyond – in model year 2021 when it unveiled a Summit snowmobile with the first-ever two-stroke engine with a factory-installed turbocharger.

Use of the technology, however, was limited to mountain sleds, and Ski-Doo officials stressed that the turbo didn’t add power to the 165-horsepower Rotax 850 on which it was installed. Instead, it just replaced the power that would have otherwise been lost to altitude. 

After Polaris unveiled its own high-output Patriot Boost factory turbo in model year 2022 for both mountain and trail applications, Ski-Doo upped the horsepower output of its 850 Turbo for model year 2023 to 180 horsepower. But the resulting 850 Turbo R engine was still restricted to mountain applications.

That changes for model year 2024. But the tech-savvy folks at Ski-Doo didn’t just “drop” their 850 Turbo R into a short chassis and call it good. Instead, they unveiled it in an MXZ X-RS with Competition Package that features a water injection system that cools the intake temperature of the turbo-heated air during long wide-open-throttle situations. This lets riders stay on the throttle longer without the engine detuning itself, Ski-Doo officials claim.

To learn more about this injection system, its development and why water is mixed with methanol, we spoke with Product Development Manager Frederic Desjardins.

Rotax Turbo 850
This image tries to portray how and where the water and methanol mix is inserted to cool warm air on its way to the cylinders on 850 Turbo R sleds.

SNOW GOER: The 850 Turbo – and then the 850 Turbo R – have been out for a couple of years for mountain applications. When in the development timeline did you know it would also be used in a flatland trail machine?

FREDERIC DESJARDINS: “We have a roadmap for the Rotax 850. We knew we were going to be adding turbo, and we knew eventually we were going to have turbo for the trail. As you witnessed, we went step-by-step. First we introduced the 850 [for model year 2017]. A few years later the 850 Turbo [was unveiled] but with the same power level as the 850. This was done on purpose to learn what we didn’t know. I mean, we knew what we knew, but to have a large mass of vehicles out there in customers hands with different behaviors and so on teaches you a lot. So, after the 165 [horsepower turbo version] was out for two years, we were able to see our assumptions and validate everything – to see the strengths and weaknesses and such.

“Again, we took the same path: We went with more power in the segment that we knew – the mountain. Once we were clear with that one, we knew we were going to the trail, but we took the learnings from the first 180 [horsepower version] winter and then we made sure our trail version would be solid, because it would be the second year in the mountains. All of this was going on in parallel.

“It’s not a secret that we are leading the market, and this is mainly because of our innovations. So there is the pressure to be the leader and continue to innovate – we are strong and we want to stay strong. We want to be solid out there. So, we knew we were going to be in trail with the turbo since we started working on the 850. It was part of our whole plan.”

SG: At what point did the concept of doing something to cool the  intake air become a discussion? In broad terms, explain the problem you’re trying to solve by cooling the intake air, and what happens if you don’t.

DESJARDINS: “The base 850 N/A [naturally aspirated] is already a strong engine. And we are already at the limit of the 91-octane gas you can get at the gas station. To increase the power above this, we cannot have hotter air [before forced into the intake], because eventually hotter air means more sensitivity to knocking [caused by uneven combustion]. This is the first symptom you are going to see. When it starts to knock we have knock detection, so we start to protect the engine by retarding the timing. We reduce the power, and you have less response. It becomes a snowball thing where it’s not efficient, not as powerful and also not reliable. So we knew we had to cool the air.

“The air temperature is not that high compared to a four-stroke with turbo boost, though, because we are not boosting to a very high level, but it can still get too high for a high-performance two-stroke. An intercooler would not be as efficient in this condition. We would need a very big intercooler but, because of the smaller temperature difference between the intake air and the outside air, the efficiency of an intercooler would be marginal, plus [there would be] pressure loss. So, we are relying on the water injection [to cool the intake air].”

2024 Ski-Doo MXZ X-RS with Competition Package
2024 Ski-Doo MXZ X-RS 850 Turbo R

SG: You’ve stated in previous discussions that power-to-weight was also a big consideration. What other issues made you turn toward water injection and away from an intercooler?

DESJARDINS: “Response. If you have an intercooler in your pipeline, the charging air circuit becomes very long. And long air intake circuits mean inertia, and inertia means lack of response. We cannot afford to have lack of response in the trails with an MXZ. When you see bumps or come out of a corner, you want the punch and you want it now. If you do exclusively lake crossings, eventually an intercooler may do the job, but not for an MXZ application.”

SG: How did you land on the concept of injecting water into the intake system? Is the technology used in other motorized applications? We understand BMW is using it in automotive, correct? 

DESJARDINS: “Yes, BMW is introducing it in the car industry for really high-end performance vehicles. But if you go to racing you will see it, especially in drag racing. They can take a small engine and supercharge it, and they are water injecting as well in those applications. So it was out there in the racing application, mainly for drag racing or over-boosted engines. But it was complex and without much technology behind it. What we did is we took kind of a simple system but we put smart things around it to make sure it was seamless.”

SG: For this application, your XPS ICE features water mixed with methanol. What is the purpose of the methanol? 

DESJARDINS: “The best thing to use would be pure water, except for the [potential of] rust, obviously. But we are working on snowmobiles so we cannot use just water in the winter. The first thing we needed to fix was preventing freezing. We want to have as much water in our mixture as possible, because the water is what takes out the energy/heat. The water gives us the result we have, not the methanol. The methanol is just a medium to avoid freezing the water. And, with methanol, we have a better ratio of water-to-methanol vs. ethanol or other fluids that fulfill our demand. However, we do not use only water and methanol: We have our own recipe, that’s why we came out with the XPS ICE product.

“Anti-freezing is the number one focus. The second is foaming. Foaming is the enemy, because if you start to push bubbles you will not have any cooling effect. In other words, if you put windshield washer fluid in there, for example, you are going to foam and you are just going to inject bubbles. So, it’s anti-freeze, anti-foaming and anti-rust – we also have an anti-rust [agent] in our plan. And it must be cost-effective for our customers at the end of the day. But the methanol is doing nothing. As soon as it goes out of the nozzle the function of the methanol is done. It is not acting on anything.”

Frederic Desjardins
Ski-Doo Product Development Manager Frederic Desjardins, pictured at the Big East Powersports Show.

SG: Let’s dig into the system: What sort of information is being fed to the ECM/ECU so it can decide when injection is necessary?

DESJARDINS: “This is where you may not like my answer! I will tell you a [general] list, but obviously this is the edge we may have on the competition. Our goal is to maintain a low air temperature, this is the result we want. As you can imagine, we are registering the RPM, throttle position, fuel consumption, the time you are wide open, the time you need power, outside air temperature, elevation and many, many other parameters that the ECM is grabbing ‘X’ thousand times per second, and we inject the right amount of water for a given condition. But in the end our goal is to be under a given air intake temperature. All actions are taken to drive that air intake temperature. But we use all of the sensors we have on the sled to build the algorithm, and this algorithm is kind of a secret, if you will.”

SG: Where and how is the fluid injected, exactly? How did you land on its injection location? For how long, how much, and at what kind of pressure?

DESJARDINS: “We inject it between the throttle plate and reed valve in the intake duct. This is the best place we found to inject it to give time for the air to cool. What we want is to use the cool water to grab the hot energy and just vaporize. So, this was the best spot in our tests to inject the water. We inject at around 20 psi. The exact [injection] spot in the end is performance-based but it’s also related to the layout of the vehicle. Access, when you do mechanical work, and the gap between water-injected engines and the one without water injection [were additional factors], so it’s also about having modularity between models. There are many things that we have to take into account when we do a new layout. Performance is top, we don’t want to compromise on performance. But there are also other considerations. It included simulations, analyzing and dyno tests, and eventually emissions, too – everything is considered in this.”

SG: You mentioned emissions. How does this engine measure up?

DESJARDINS: “We are proud to say that our turbo engines meet EPA regulations. So the E-TEC combined with the Rotax Turbo and water injection is very, very good in terms of emissions and fuel consumption, too. For sure if you use all of the 180 ponies you are still going to meet the EPA emission, but you are going to need more fuel, as you can imagine.”

SG: How big is your reservoir that holds the water/methanol mix, how soon will people go through a tank load, and was placement of that jug strategic?

DESJARDINS: “The jug is 1.2 liters. You can use none, or you can empty the bottle after 22 to 24 kilometers [13 to 15 miles] of wide-open throttle. So, if you start from a dead stop [and pin the throttle], and let’s say it’s between 0 and -5 [Celsius], after 22 to 24 kilometers, your 1.2 liters will be gone. Now, if you are on a twisting trail, you may not use a drop in a full day because you need to reach a situation that will activate the system. Riding here, for instance, from Valcourt to Sherbrooke [in Quebec], there is low probability you are going to use any water. The only place [around here] that you are going to use it is on a lake. If it is quite cold outside, it can be over 10 seconds [of wide-open throttle] before the system injects any water. And if it is very, very cold, let’s say like minus 30 or minus 35, you may not use a drop even if you go wide open. But it is rare that you’d go wide-open for a long time at minus 35 (laughs).”

SG: What happens if you run out of fluid and the intake air heats up?

DESJARDINS: “If we don’t cool it at all, at the end you’re going to be left with a 165-horsepower engine. It’s not a bad thing in a way that the system is so seamless and so not intrusive that, in case you don’t have any liquid, you will be at worst like an N/A version, except with the turbo clutch setup. If you remember only one thing, it’s that this system will make the performance of your vehicle constant at any given temperature or altitude. Without a good air-cooling system, performance will be up and down and so would the long-term durability.”

 SG: We’ve learned from racing applications that humid air carries less oxygen and thus makes less power. Explain why that isn’t a factor or how that’s overcome when purposely injecting water into the intake.

DESJARDINS: “Here I will give you a bit of a secret. Our turbo is quite big, so we don’t use the full potential of it – we still have some room. When we inject water, we increase the boost so it is seamless for the customer. Because if you just inject water without increasing the boost, you are going to feel something. But all of this is happening seamlessly, and you feel nothing [different happening]. To compensate for that loss in the combustion chamber, we increase the pressure. We use additional boost pressure and other parameters to maintain the exact same power level.

“That speaks to how sophisticated the algorithm is and how sophisticated the electronics and the motor are that the team has designed. When you think about the ability to adjust the boost pressure because water suddenly is being injected, the parameters that it must process and the brainpower that it must take for the computer inside the machine is phenomenal. And we own all of this. The computer is our computer, the black box is our design, everything is in our hands with many patents around it. I am lucky to be surrounded by the best two-stroke team on earth.”

SG: What were the biggest hurdles or challenges when developing this system?

DESJARDINS: “The biggest thing was to have the full performance in a seamless way. Having water injection, we need to play with the fuel amount, with pressure and with other parameters to make it seamless. So, today our turbo is flawless, you don’t feel it, as you noticed when you drove it. Some people might like us to be a bit more harsh sometimes. I like to compare our [two-stroke] package with the [Porsche] 911, and the four-stroke turbo to a [Ford] Mustang. It’s refinement vs. the muscle feeling.  We are refined. From the engagement point to the top end, it is always linear. Once it starts to inject it stays linear. So the durability and everything around this makes it easy for the customer to manage. You asked earlier why the bottle was at the back [of the machine, behind the seat]. It was because we did not want to add a gauge or make people open a door [side panel] to look at the liquid level and such. So having it there with a clear tank, you see right away where you are at. It is high-tech, but it must be seamless for the end user.”  

SG: Now that the project is done, what makes you and your team most proud now that it’s in the field?

DESJARDINS: “There are a few things. The first thing is we are again the first to show new technology. We clearly go in the direction of innovation, and we are recognized as an innovator in the snowmobile business. We are first again with a given technology in a snowmobile. The second is that you can have MXZ DNA with a turbo. There’s a huge response, it’s light, you can go through the ditch with it, you don’t feel the weight of a four-stroke and in the bumps, you have the exact same feeling as an 850 N/A, and you have that full response with great power. So, we have the benefit of the turbo without any drop, any lag, anything. We are proud to be the first in the field, but it is not good enough to be first: You have to be first with something that is good but there is a second layer. Our technology is very, very good so this at the end is what we are proud of. And, personally, I am proud to represent BRP in this and lead this group, because the team we have to make this happen is the best. Like you, I read many things on two strokes in everything from motorcycles to chainsaws and this and that, but there is nothing out there that is at our level.”

Editor’s Note: Every Snow Goer issue includes in-depth sled reports and comparisons, aftermarket gear and accessories reviews, riding destination articles, do-it-yourself repair information, snowmobile technology and more. Subscribe to Snow Goer now to receive print and/or digital issues.

5 thoughts on “Ski-Doo Designer Shares Secrets Of 850 Turbo R Water Injection System

  • Methanol does increase octane and in fact cools better than water, despite his claims.
    They also had a lot of failures, caused by faulty injection parts putting excessive amounts of fluid in the engine while not running. This caused the engine to hydraulic after starting bending rods, cranks, etc. The parts required to fix the problem were on backorder most of the season.
    This system is going to be a maintenance nightmare, as anyone who’s run water Meth before will tell you, methanol is extremely corrosive. Just wait for the flood of problems online this fall when owners go to fire up their 25k sled.

    Reply
  • Super Charger patents are long expired and would be a cheaper more reliable option to boost power for sleds, SxS and ATVs. Less heat issues and fire issues as well. Plus no turbo lag ever.

    Reply
  • So now I have to fill my sled up with gas, oil, AND water….. great 👍

    Reply
  • Avatar for Brett

    I can tell you after your personally trying it and running it for over a season it is awesome, flawless, and it has a great smell!

    Reply

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