The Harley-Davidson Dyna lineup is a popular series of motorcycles known for their classic cruiser styling and air-cooled engines. While Harley-Davidson has incorporated liquid-cooling in some of their more recent models, the Dyna series has traditionally featured air-cooled powerplants.
Understanding Harley-Davidson’s Cooling Systems
Harley-Davidson motorcycles have historically utilized two primary cooling methods:
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Air-Cooling: This is the traditional cooling system found on many Harley models, including the Dyna lineup. Air-cooled engines rely on the natural flow of air over the engine cylinders and fins to dissipate heat. This design is simpler, lighter, and requires less maintenance compared to liquid-cooling systems.
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Liquid-Cooling: More recently, Harley-Davidson has introduced liquid-cooled engines in select models. This includes the Street series, Sportster S, V-Rod, Ultra Limited, and some Custom Vehicle Operations (CVO) models. Liquid-cooled engines use a coolant fluid circulated through the engine block and cylinder heads to absorb and dissipate heat.
The Harley Dyna Series
The Harley Dyna series, which was produced from 1991 to 2017, is known for its classic cruiser styling and air-cooled engines. Some key specifications of the Dyna models include:
| Model | Engine Displacement | Cooling System |
|---|---|---|
| Dyna Super Glide | 1,584 cc (96.7 cu in) | Air-Cooled |
| Dyna Low Rider | 1,584 cc (96.7 cu in) | Air-Cooled |
| Dyna Wide Glide | 1,584 cc (96.7 cu in) | Air-Cooled |
| Dyna Street Bob | 1,584 cc (96.7 cu in) | Air-Cooled |
As you can see, all Dyna models featured air-cooled engines, which was a hallmark of the Dyna lineup. Harley-Davidson did not offer any water-cooled Dyna models during the production run of this series.
Liquid-Cooled Cylinder Heads
While the Dyna series did not feature water-cooled engines, Harley-Davidson has incorporated liquid-cooled cylinder heads in some of their models since 2014. This was primarily done to improve cooling of the exhaust valves, rather than cooling the entire engine block.
The liquid-cooled cylinder head design works as follows:
- Coolant Circulation: A small coolant pump circulates coolant through the cylinder heads, specifically around the exhaust valves.
- Heat Dissipation: The coolant absorbs heat from the exhaust valves and transfers it to the surrounding air through a small radiator.
- Improved Cooling: This targeted liquid-cooling of the exhaust valves helps to prevent valve float and improve engine performance, particularly at higher RPMs.
However, it’s important to note that this liquid-cooled cylinder head design is not the same as a full water-cooled engine found in other Harley models. The Dyna series continued to use traditional air-cooled engines throughout its production run.
Advantages and Disadvantages of Air-Cooling vs. Liquid-Cooling
Both air-cooled and liquid-cooled engine designs have their own advantages and disadvantages:
Air-Cooled Advantages:
– Simpler and lighter design
– Lower maintenance requirements
– Lower manufacturing costs
Air-Cooled Disadvantages:
– Less effective cooling at high RPMs and under heavy loads
– Potential for hot spots and uneven cooling
Liquid-Cooled Advantages:
– More effective cooling, especially at high RPMs and under heavy loads
– Ability to maintain more consistent engine temperatures
– Improved performance and reliability under demanding conditions
Liquid-Cooled Disadvantages:
– More complex and heavier design
– Higher maintenance requirements (e.g., coolant changes)
– Higher manufacturing costs
The choice between air-cooling and liquid-cooling often comes down to the intended use and performance requirements of the motorcycle. Harley-Davidson has utilized both cooling systems in their lineup, with the Dyna series remaining firmly in the air-cooled camp.
Conclusion
In summary, the Harley Dyna series is not a water-cooled motorcycle. The Dyna lineup has traditionally featured air-cooled engines, which is a hallmark of the classic cruiser design. While Harley-Davidson has incorporated liquid-cooled cylinder heads in some of their more recent models, the Dyna series has remained true to its air-cooled roots throughout its production run.
Reference:
– Harley-Davidson Cooling Systems Explained
– Harley-Davidson Dyna Series Overview
– Liquid-Cooled Cylinder Heads in Harley-Davidson Engines