Stihl MS 391 Specifications (5 Key Features for Pro Woodcutters)

As someone deeply involved in the world of wood processing and firewood preparation, I understand the importance of getting the most bang for your buck. That’s why I’m always on the lookout for tools that offer a great balance of performance and price. The Stihl MS 391 chainsaw is a model that often comes up in these discussions, especially among those who need a reliable workhorse without breaking the bank. In this article, I’ll delve into the key specifications and features that make the MS 391 a compelling option for professional woodcutters, and how these features translate into measurable benefits for your projects.

Stihl MS 391 Specifications: 5 Key Features for Pro Woodcutters

Tracking key performance indicators (KPIs) in wood processing and firewood preparation is essential for optimizing efficiency, reducing costs, and ensuring the quality of your final product. Whether you’re a seasoned logger or a weekend warrior, understanding these metrics will help you make data-driven decisions and improve your overall operations. Below, I’ll outline five crucial features of the Stihl MS 391 and how they relate to key project metrics in our industry, providing actionable insights to help you achieve success.

Why Track These Metrics?

Before we dive in, let’s quickly address why tracking metrics matters. Imagine you’re running a firewood business. Without tracking metrics like wood volume yield or drying time, you’re essentially flying blind. You might be wasting valuable resources, selling poorly seasoned wood, or missing opportunities to improve your processes. By tracking these metrics, you can identify bottlenecks, optimize your workflow, and ultimately, increase your profitability.

Here are the five key features of the Stihl MS 391, along with the project metrics they impact:

1. Engine Power and Displacement

• Definition: The engine power, typically measured in horsepower (hp) or kilowatts (kW), indicates the engine’s ability to perform work. Displacement, measured in cubic centimeters (cc), refers to the volume of the engine’s cylinders. The Stihl MS 391 boasts a 64.1 cc engine producing 4.4 bhp (3.2 kW).

• Why It’s Important: Engine power directly impacts the chainsaw’s cutting speed and ability to handle larger diameter logs. Higher power allows for faster cutting, reducing the time required to process wood. It also enables the saw to handle tougher wood species and larger tasks with greater ease. For example, if you regularly cut hardwood like oak or maple, a more powerful saw will significantly improve your efficiency.

• How to Interpret It: A higher horsepower rating generally translates to faster cutting speeds and the ability to handle larger, more demanding tasks. However, it’s crucial to consider the overall design and efficiency of the engine. A well-designed engine with moderate horsepower can often outperform a poorly designed engine with higher horsepower.

• How It Relates to Other Metrics: Engine power is directly related to Time per Cut (TPC) and Wood Volume Yield Efficiency (WVYE). A more powerful engine will generally result in a lower TPC and a higher WVYE, as you can process more wood in less time. It also affects Fuel Consumption Rate (FCR); higher power typically means higher fuel consumption.

  • Time per Cut (TPC): This metric measures the time it takes to complete a single cut. A powerful engine, like the one in the MS 391, can significantly reduce TPC, leading to faster overall project completion. I once worked on a project where we compared two chainsaws with different engine powers. The more powerful saw reduced the TPC by 20%, resulting in a substantial time saving over the course of the project.

  • Wood Volume Yield Efficiency (WVYE): This metric assesses how much usable wood you obtain from each tree or log. A powerful and efficient saw can help minimize waste and maximize yield. For example, a cleaner, faster cut can reduce splintering and other forms of waste, leading to a higher WVYE.

  • Fuel Consumption Rate (FCR): This metric tracks the amount of fuel consumed per unit of time or volume of wood processed. While a more powerful engine might consume more fuel, it can also be more efficient in the long run if it allows you to process more wood in less time.

  Example:

  Let’s say you’re cutting firewood. With a less powerful saw, it might take you 10 minutes to cut a log into manageable pieces. With the MS 391, you might be able to do the same job in 7 minutes. This translates to a 30% reduction in TPC, allowing you to process significantly more firewood in a given timeframe. However, the MS 391 might consume slightly more fuel per hour compared to the less powerful saw. Therefore, you need to consider the trade-off between speed and fuel consumption to optimize your overall efficiency.

2. Bar Length and Cutting Capacity

• Definition: Bar length refers to the length of the guide bar on the chainsaw, which determines the maximum diameter of wood that can be cut. The Stihl MS 391 is typically available with bar lengths ranging from 16 to 20 inches. Cutting capacity is the actual diameter of wood that the saw can comfortably and efficiently cut.

• Why It’s Important: Bar length directly impacts the size of logs you can handle. A longer bar allows you to cut larger diameter trees, while a shorter bar is more maneuverable for smaller tasks. Choosing the right bar length for your typical workload is crucial for efficiency and safety. Using a bar that’s too short for the job can be dangerous and inefficient, while a bar that’s too long can be cumbersome and difficult to control.

• How to Interpret It: Consider the typical size of the trees you’ll be cutting. If you primarily cut small to medium-sized trees, a 16-inch bar might be sufficient. However, if you regularly cut larger trees, a 20-inch bar would be a better choice. It’s also important to consider the power of the saw. A longer bar requires more power to operate effectively.

• How It Relates to Other Metrics: Bar length is closely related to Wood Diameter Capacity (WDC) and Saw Chain Sharpening Frequency (SCSF). A longer bar allows you to cut larger diameter trees (higher WDC), but it also requires more frequent sharpening (higher SCSF) due to increased friction and wear.

  • Wood Diameter Capacity (WDC): This metric represents the maximum diameter of wood that the chainsaw can effectively cut. A longer bar increases the WDC, allowing you to handle larger logs. However, it’s important to ensure that the engine has sufficient power to drive the longer bar.

  • Saw Chain Sharpening Frequency (SCSF): This metric measures how often the saw chain needs to be sharpened to maintain optimal cutting performance. A longer bar and tougher wood species can increase the SCSF, requiring more frequent maintenance.

  Example:

  Imagine you’re clearing a plot of land for a new construction project. The trees on the property range in diameter from 10 inches to 24 inches. In this case, a 20-inch bar on the MS 391 would be ideal, allowing you to handle the majority of the trees without struggling. However, if the property only had trees with a maximum diameter of 14 inches, a 16-inch bar would be more than sufficient and potentially more maneuverable. Furthermore, cutting hardwoods like oak with a 20-inch bar will require more frequent chain sharpening compared to cutting softwoods like pine with a 16-inch bar.

3. Weight and Ergonomics

• Definition: Weight refers to the overall weight of the chainsaw, typically measured in pounds (lbs) or kilograms (kg). Ergonomics refers to the design of the chainsaw, including the handle placement, balance, and vibration dampening features. The Stihl MS 391 weighs approximately 13.7 lbs (6.2 kg) without the bar and chain.

• Why It’s Important: Weight and ergonomics directly impact operator fatigue and safety. A lighter saw is easier to handle and reduces fatigue during extended use. Ergonomic features, such as anti-vibration systems and comfortable handles, can further reduce fatigue and improve control, minimizing the risk of accidents.

• How to Interpret It: Consider the amount of time you’ll be spending using the chainsaw. If you’re only using it for short periods, weight might not be a major concern. However, if you’re using it for several hours a day, a lighter saw with good ergonomics will significantly reduce fatigue and improve your overall productivity.

• How It Relates to Other Metrics: Weight and ergonomics are closely related to Operator Fatigue Rate (OFR) and Accident Frequency Rate (AFR). A lighter saw with good ergonomics will result in a lower OFR and a lower AFR.

  • Operator Fatigue Rate (OFR): This metric measures the rate at which the operator becomes fatigued during chainsaw operation. A heavier saw with poor ergonomics will lead to a higher OFR, reducing productivity and increasing the risk of errors.

  • Accident Frequency Rate (AFR): This metric tracks the number of accidents or near-misses that occur during chainsaw operation. A fatigued operator is more likely to make mistakes, increasing the risk of accidents. A lighter, more ergonomic saw can help reduce fatigue and improve control, leading to a lower AFR.

  Example:

  I once worked on a large-scale logging project where we were felling trees for several hours each day. We used a variety of chainsaws, some of which were significantly heavier than others. The operators using the heavier saws reported higher levels of fatigue and were more prone to making mistakes. We eventually switched to lighter, more ergonomic models, which significantly improved operator comfort and reduced the number of accidents. The MS 391, with its relatively light weight and ergonomic design, can help minimize operator fatigue and improve safety, especially during long workdays.

4. Fuel Efficiency and Tank Capacity

• Definition: Fuel efficiency refers to the amount of fuel the chainsaw consumes per unit of time or volume of wood processed. Tank capacity refers to the size of the fuel tank, which determines how long the chainsaw can run before needing to be refueled. The Stihl MS 391 has a fuel tank capacity of 20.3 oz (0.6 liters).

• Why It’s Important: Fuel efficiency directly impacts operating costs. A more fuel-efficient saw will save you money on fuel in the long run. Tank capacity affects how frequently you need to stop and refuel, which can impact productivity. A larger tank capacity allows you to work for longer periods without interruption.

• How to Interpret It: Compare the fuel efficiency of different chainsaws based on their specifications and user reviews. Consider the size of your typical projects and how frequently you’ll need to refuel. A larger tank capacity might be beneficial if you’re working in remote areas where refueling is difficult.

• How It Relates to Other Metrics: Fuel efficiency and tank capacity are closely related to Fuel Cost per Volume (FCV) and Refueling Downtime (RD). A more fuel-efficient saw will result in a lower FCV, while a larger tank capacity will reduce RD.

  • Fuel Cost per Volume (FCV): This metric measures the cost of fuel required to process a specific volume of wood. A more fuel-efficient saw will result in a lower FCV, reducing overall operating costs.

  • Refueling Downtime (RD): This metric tracks the amount of time spent refueling the chainsaw. A larger tank capacity will reduce the frequency of refueling, minimizing RD and increasing productivity.

  Example:

  Let’s say you’re running a firewood business. You estimate that you process 10 cords of wood per week. A more fuel-efficient saw might consume 5 gallons of fuel per week, while a less fuel-efficient saw might consume 7 gallons. At a fuel cost of $3 per gallon, the more fuel-efficient saw would save you $6 per week, or $312 per year. Furthermore, a larger tank capacity will reduce the number of times you need to stop and refuel, saving you valuable time and increasing your overall productivity. Even a few minutes saved per refueling can add up over the course of a week or month.

5. Anti-Vibration System

• Definition: An anti-vibration system is a design feature that reduces the amount of vibration transmitted from the chainsaw’s engine to the operator’s hands and arms. This is typically achieved through the use of rubber mounts or other vibration-dampening materials. The Stihl MS 391 features an advanced anti-vibration system designed to minimize operator fatigue.

• Why It’s Important: Excessive vibration can lead to a condition called “white finger” or “vibration white finger” (VWF), which is a painful and debilitating condition that affects the blood vessels and nerves in the hands and fingers. An effective anti-vibration system is crucial for protecting the operator’s health and well-being, especially during prolonged use.

• How to Interpret It: Look for chainsaws with well-designed and effective anti-vibration systems. Read user reviews and consult with experienced loggers or arborists to get their opinions on the effectiveness of different systems. A good anti-vibration system should significantly reduce the amount of vibration felt by the operator, allowing for longer and more comfortable use.

• How It Relates to Other Metrics: An anti-vibration system is closely related to Operator Health and Safety (OHS) and Long-Term Productivity (LTP). A more effective anti-vibration system will improve OHS and increase LTP by reducing the risk of VWF and other vibration-related injuries.

• Long-Term Productivity (LTP): This metric measures the operator’s ability to maintain productivity over the long term. VWF and other vibration-related injuries can significantly reduce LTP by forcing operators to take time off work or even change careers. An effective anti-vibration system can help prevent these injuries and maintain LTP.

Example:

I’ve personally witnessed the devastating effects of VWF on experienced loggers. Some of them were forced to retire early due to the pain and discomfort caused by this condition. Using chainsaws with effective anti-vibration systems is a crucial step in preventing VWF and protecting the health and well-being of chainsaw operators. The Stihl MS 391’s anti-vibration system is designed to minimize vibration and reduce the risk of VWF, allowing operators to work comfortably and safely for longer periods.

Applying These Metrics to Improve Future Projects

Now that we’ve explored these five key features of the Stihl MS 391 and their impact on project metrics, let’s discuss how you can apply this knowledge to improve your future wood processing or firewood preparation projects.

1. Track Your Data: The first step is to start tracking your data. Use a spreadsheet or a dedicated software program to record key metrics such as TPC, WVYE, FCR, OFR, and AFR. This will provide you with valuable insights into your current performance and identify areas for improvement.

2. Set Realistic Goals: Once you have a baseline of data, set realistic goals for improvement. For example, you might aim to reduce your TPC by 10% or increase your WVYE by 5%.

3. Experiment and Optimize: Experiment with different techniques and equipment to see what works best for you. For example, you might try using a different type of saw chain or adjusting your cutting technique. Track your results and make adjustments as needed.

4. Regularly Review Your Progress: Regularly review your progress and make adjustments to your goals and strategies as needed. This will ensure that you’re continuously improving your performance and maximizing your efficiency.

5. Invest in Quality Equipment: Investing in high-quality equipment, such as the Stihl MS 391, can significantly improve your performance and reduce your operating costs in the long run. Choose equipment that is well-suited for your specific needs and that offers a good balance of performance, durability, and fuel efficiency.

6. Maintain Your Equipment: Regular maintenance is essential for keeping your equipment in top condition and maximizing its lifespan. Follow the manufacturer’s recommendations for maintenance and repair, and address any issues promptly.

7. Prioritize Safety: Safety should always be your top priority. Wear appropriate personal protective equipment (PPE), such as a helmet, eye protection, hearing protection, and gloves. Follow safe operating procedures and never take unnecessary risks.

Personalized Stories and Unique Insights

Throughout my years in the wood processing industry, I’ve learned that there’s no substitute for experience. I’ve also learned that data-driven decision-making is essential for success. By tracking key metrics and analyzing your results, you can identify opportunities to improve your efficiency, reduce your costs, and enhance the quality of your work.

For example, I once worked on a project where we were tasked with clearing a large area of forest for a new development. We initially used a variety of different chainsaws, but we quickly realized that some were significantly more efficient than others. By tracking metrics such as TPC and FCR, we were able to identify the most efficient saws and focus our efforts on using those models. This resulted in a significant reduction in our overall project costs and allowed us to complete the project ahead of schedule.

Challenges Faced by Small-Scale Loggers and Firewood Suppliers Worldwide

I understand that small-scale loggers and firewood suppliers around the world face unique challenges, such as limited access to capital, unreliable equipment, and fluctuating market prices. However, by focusing on efficiency and quality, you can overcome these challenges and build a successful business.

• Limited Access to Capital: Start small and reinvest your profits back into your business. Consider leasing equipment instead of buying it outright.

• Unreliable Equipment: Invest in high-quality equipment that is durable and reliable. Maintain your equipment regularly and address any issues promptly.

• Fluctuating Market Prices: Diversify your product offerings and explore new markets. Build strong relationships with your customers and suppliers.

Conclusion

The Stihl MS 391 is a versatile and reliable chainsaw that offers a good balance of performance and price. By understanding the key features of this saw and how they relate to project metrics, you can make informed decisions and improve your overall efficiency. Remember to track your data, set realistic goals, experiment and optimize, and prioritize safety. By following these steps, you can achieve success in your wood processing or firewood preparation projects.

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