Snowmobiling enthusiasts often face the dilemma of choosing between 2-stroke and 4-stroke engines. The decision transcends personal preference, as opting for either will impact the snowmobile’s performance and the rider’s trail experience. This article will cover the unique attributes of each engine type to help you make an informed decision.
What is the difference between a 2-stroke and a 4-stroke snowmobile engine? The main differences between 2-stroke and 4-stroke snowmobile engines are their configuration, power delivery, and intended use. Depending on displacement, the kind of powerplant your snowmobile has, and how you ride, one engine type may prove superior or outdo the other.
We’ll dive into these differences and many more while answering which is better. As a bonus, I’ll throw in a comparison table of the fundamental specs of these power mills and lists of their highlights and drawbacks.
I can’t promise that choosing between these two snowmobile engines would come easily after reading this piece. However, I can guarantee you’ll feel more assured in making the right choice!
Forerunners of the Snowmobile Engine
To grasp the distinct attributes of 2-stroke and 4-stroke snowmobile engines, it’s crucial to explore their origins and the onset of their widespread commercial adoption. To do this, we must go back to the 18th and 19th centuries — an era marked by the beginning of global industrialization.
The inception of 2-stroke and 4-stroke power mills dates back to the pre-industrialization period. Initial endeavors to prototype internal combustion engines (ICE) began as early as the 17th century. However, the designs that laid the groundwork for contemporary, mass-produced snowmobile engines didn’t come to fruition until a decade before the 2nd Industrial Revolution.
In some sources, Jean Joseph Étienne Lenoir is credited for creating the antecedent to 2-stroke engines, the 1860 Lenoir engine. In others, it’s Sir Dugald Clerk and his 1881 patent. The first practical 2-stroke engine — a liquid-cooled twin-cylinder mill — is attributed to Alfred Angas Scott. Meanwhile, the first valveless design is credited to English engineer Joseph Day.
Regarding 4-stroke engines, Alphonse Beau de Rochas is credited with publishing the theoretical principles of this configuration in 1862. However, German engineer Nikolaus Otto accomplished the successful prototype in 1876.
Karl Benz, a German inventor, then crafted his single-cylinder gasoline 4-stroke motor in 1879. Subsequently, Gottlieb Daimler and Wilhelm Maybach achieved the development of the first high-speed, gas-fed 4-stroke engine in 1883.
The Trailblazing 2-Stroke
Debates persist regarding the beginnings of 2-strokes and 4-strokes and their chronological order. Clear evidence indicates the 2-stroke engine predates its counterpart by two years — as proven by the 1860 Lenoir engine.
Lenoir’s design ran on illuminating gas and employed a 2-stroke cycle. Categorically, it paved the way not only for 2-strokes but also for internal combustion engines in general.
However, a bigger percentage of the riding community alludes to the commercial availability timeline of each engine. In this context, the 4-stroke engine takes the win since it was the first commercially available power mill. Otto completed his 4-stroke design in 1876, while Sir Dugald Clerk produced his 2-stroke design in 1878.
Dates aside, it doesn’t help that Lenoir’s engine had glaring performance limitations and high fuel consumption — probably why it’s easily disregarded as a precursor to modern-day 2-stroke engines.
Still, we can’t overlook the fact that Clerk’s design was undeniably innovative (to say the least). This should be no surprise since his work was grounded in his pursuit of simplicity and desire to streamline the combustion process.
By compressing the four stages of the engine cycle into two strokes, the said design eliminated the need for a separate valvetrain, making the engine inherently lighter and more straightforward.
In subsequent decades, engineers and inventors further refined the 2-stroke engine. Its evolution continued into the 20th century, finding applications in motorcycles, chainsaws, and, eventually, snowmobiles.
The uncomplicated nature and potent power output of 2-stroke engines made them well-suited for recreational vehicles and preferred in scenarios where power-to-weight ratio and ease of maintenance are paramount.
The advent of the 4-Stroke Engine
The inception of the 4-stroke engine unfolded in the 19th century — in 1876, to be exact. Renowned German engineer Nikolaus Otto played a pivotal role in creating the first successful 4-stroke power mill.
Otto aspired to enhance the efficiency and reliability of existing engines by putting Beau de Rochas’ theories into practice. This led him to devise an ingenious mechanism dividing the engine cycle into four distinct strokes: intake, compression, power, and exhaust.
Central to Otto’s innovation was a separate combustion chamber, a deviation from prevailing engine designs at the time. This allowed for a more controlled and efficient combustion process, enhancing the engine’s overall performance. 4-strokes, now synonymous with Otto’s name, marked a significant departure from the hefty steam engines and simpler 2-stroke power mills.
By dedicating a stroke to each phase of the cycle, Otto’s design achieved an unprecedented level of precision and control. This, in turn, not only translated to improved engine efficiency but also paved the way for its smoother operation and reduced wear and tear.
Nikolaus Otto’s groundbreaking invention set the stage for the widespread adoption of 4-stroke engines across various industries, eventually reaching the snowmobiling realm during the 1990s. The design’s inherent advantages — such as enhanced fuel efficiency and lower emissions — made it a preferred choice for applications ranging from automobiles to industrial machinery.
TIP: For more details on how 2-stroke and 4-stroke engines work, refer to my post on How Do Dirt Bike Engines Work? (2 & 4 Stroke).
The Shift in Snowmobile Engines
2-strokes didn’t become the favored snowmobile engine until the 1950s — for the simple fact that snowmobiles weren’t invented until then. Emission regulations weren’t as strict as they are now. So, it would make sense for manufacturers to equip their snow machines with 2-stroke engines. However, as technological advancements shaped the industry, the latter part of the 20th century saw the rise of 4-stroke mills.
The transition to 4-stroke snowmobile engines aligned with evolving environmental regulations. These power mills were also known for their durability and enhanced fuel efficiency. Despite this shift, 2-stroke engines retained a significant presence, particularly in high-performance and racing models, where their immediate power delivery and lighter weight remained appealing for riders with a penchant for speed and agility.
Snowmobile Engine Comparison
Although 4-stroke snowmobile engines beat their 2-stroke counterparts in number by a landslide, some savants and riding enthusiasts still prefer the simpler engine design. High-performance racing applications are just one of the many reasons for this preference.
For a more extensive rundown of considerations and differences between the two engine types, refer to the table below:
| Parameter | 2-Strokes | 4-Strokes |
|---|---|---|
| Engine Life Expectancy (average) | 5,000—12,000 miles, depending on upkeep and if disused or utilized frequently | 10,000—30,000 miles, can extend to 40,000 miles with good maintenance |
| Horsepower | 7—210+ hp (5.2—156.5+ kW) depending on model and displacement | |
| Torque | 8.3—176.3+ Nm (0.85—17.98+ kgf-m, 6.1—130+ ft-lb), depending on engine type, displacement, and RPM | |
| Speed Rating | 8—128+ mph (12.9—205+ km/h) | 83—118+ mph (133.6—190+ km/h, 500cc and above) |
| Permissible Fuel Blend/s | Dependent on OEM specifications; oil-to-fuel ratio is typically from 40:1 to 50:1 | Gasoline variants dependent on OEM specs; B5 fuel with up to 15% ethanol for diesel-fed engines |
| Noise Level/s | From 50 feet away: 78 dB of noise or less (average); 68—73 dB @ 15 mph | |
2-Stroke vs 4-Stroke — Pros and Cons
In addition to the technical specifications above, here are some other pointers you may want to consider before opting for a specific snowmobile engine:
2-Stroke Snowmobile Engines
Pros
High Power-to-Weight Ratio
2-stroke snowmobile engines boast a remarkable power-to-weight ratio, ensuring robust acceleration and power delivery in a lightweight configuration. This is attributed to their ability to generate high RPMs, providing efficiency in power utilization.
Simplicity and Minimal Moving Parts
With fewer moving parts than their 4-stroke counterparts, 2-stroke engines shine due to their straightforwardness and ease of maintenance. This characteristic simplifies the manufacturing process and contributes to straightforward and cost-effective upkeep.
Wide Powerband for Immediate Response
2-stroke engines exhibit a wide powerband, delivering power within a narrow range of rotational speeds. This feature lends to the snowmobile’s enhanced performance and quick, immediate response.
Increased Horsepower Output
Due to their design and simplified combustion process, these power mills generate higher horsepower per cylinder displacement than 4-stroke snowmobile engines, contributing to their impressive performance capabilities.
Cons
Emissions Concerns
Compared to their same-class 4-stroke counterparts, 2-stroke snowmobile engines tend to produce higher exhaust emissions, including hydrocarbons.
Oil-Mixing Challenges
These engines necessitate the pre-mixing of oil with fuel, resulting in potential issues if the mixture is not precisely blended. Furthermore, this process adds complexity to the fueling aspect of 2-stroke engines.
Limited Longevity
Historically, 2-stroke engines only lasted 5000-8000 miles before necessitating engine maintenance. This limited lifespan may be a deal-breaker for some enthusiasts.
Frequent Upkeep
Maintenance for 2-stroke engines is more frequent than same-class 4-stroke counterparts, requiring riders to invest more time and effort in keeping the engine and the snowmobile in optimal condition.
Learning Curve
While upkeep on these power mills is simplified, 2-stroke engines may require riders to adapt to the intricacies of proper oil mixing and more regular maintenance schedules. The adjustment may come as a surprise to those who previously owned 4-stroke snowmobiles.
Reduced Mileage
2-stroke engines are often perceived as less fuel-efficient due to the combustion of the oil-gasoline mixture for lubrication — limiting the engine’s suitability for long-distance rides. This reduced mileage might deter riders who prefer extended journeys, similar to bullet #3.
Higher Operational Costs
Although the initial purchase cost may be lower, owning a snowmobile with a 2-stroke engine can lead to higher operational costs.
4-Stroke Snowmobile Engines
Pros
Environmental Compliance
4-stroke engines align seamlessly with evolving environmental regulations, producing fewer emissions and meeting stringent environmental standards. This compliance is crucial for certain regions where snowmobile trails are located.
Durability and Longevity
Renowned for these attributes, 4-stroke snowmobile engines are designed with a dedicated lubrication system. This design choice enhances their lifespan, contributing to extended periods of reliable performance.
Improved Fuel Efficiency
4-stroke engines often exhibit superior fuel efficiency, reducing the frequency of refueling and allowing for longer rides on the same amount of fuel. This increased fuel mileage is a big plus for riders who prefer leisurely cruising and extended journeys.
Efficiency at Lower RPMs
These power mills can achieve higher speeds with lower RPMs. This efficiency in power utilization contributes to both performance and fuel economy.
Higher Torque
As if to compensate for slightly inferior power output, 4-stroke engines generate higher torque per cylinder displacement — enhancing their overall power delivery and performance capabilities.
Longevity and Reduced Maintenance
Typically boasting a longer lifespan than their 2-stroke counterparts, 4-stroke engines often require less frequent upkeep, reducing the maintenance burden on riders.
Cons
Greater Complexity and More Moving Parts
Because they’re a more advanced technology, 4-stroke engines are typically more intricate and incorporate more moving parts than 2-stroke snowmobile engines. This results in elevated manufacturing and maintenance costs and a need for more advanced mechanical savvy regarding modifications and repairs.
Weight Consideration
Relative to bullet #1, 4-stroke engines generally carry more weight than 2-strokes. Additionally, their more robust cooling system, heavier build, and dedicated lubrication system contribute to this increased weight.
Power Band Characteristics
4-stroke snowmobile engines may boast a wider powerband, but they might not deliver the same immediate power as 2-strokes, especially in high-performance situations.
Inferior Power-to-Weight Ratio
Because they have slightly reduced power outputs and are heavier, these engines tend to have a lower power-to-weight ratio than 2-stroke power mills.
Lower RPM
Generally, 4-stroke engines have lower RPMs than their 2-stroke counterparts. This, in turn, may result in limitations in power delivery, especially at higher speeds. A lower RPM can impact the engine’s ability to generate sufficient power and torque, potentially leading to slower acceleration and reduced overall performance.
Higher Initial Cost
Regardless of whether used or brand-new, the initial purchase price of 4-strokes is often higher than 2-stroke snowmobile engines due to their more complex design and additional components.
Conclusion — 2-Stroke vs. 4-Stroke Snowmobile Engines
Exploring the evolution and differences between 2-stroke and 4-stroke snowmobile engines never fails to provide valuable insights. Each engine type has its strengths and weaknesses, catering to diverse situations and riding styles. Ultimately, determining the ‘best’ snowmobile engine hinges on performance expectations, personal and maintenance preferences, and environmental factors.
Hopefully, this guide helped you in this decision-making endeavor.
Kris is an avid off-roader and outdoor enthusiast who loves to brave the elements and take on challenging terrain. He also enjoys sharing his passion and knowledge with others so that they, too, can appreciate the ride.
About Kris