The Engines, They Are A-Changin’: A Comparison of Air-Cooled and Liquid-Cooled Engines

Change is coming. And for Triumph, a company built on over a century of heritage and tradition with a loyal following of riders who firmly believe in both of which, change is something that will do more than lift a few eyebrows. The change referred to, of course, is the transition from air-cooled engines to liquid-cooled engines. But why is Triumph making these changes? What are the costs and benefits? Why are people taking up arms about it? If you’re thinking about getting one of the many new Triumphs like the Street Twin, Bonneville T120, or Thruxton R, you’re probably considering these questions for yourself. So let’s take a look.

Traditionally, Triumph, like almost all other motorcycle manufacturers, always used air-cooled engines to power their motorcycles. Air-cooled engines are simple, reliable, and look great. When you think of a classic motorcycle engine, you think of rows of nicely sanded fins adorning the cylinders. But those fins aren’t just for looks. Those fins are designed to dissipate heat into the surrounding air, so that as you ride, the air passing over the engine pulls the heat out of the fins and thus out of the engine. Hence — air-cooled.

Due to this design, air-cooled engines have a broader operating temperature range. Since they rely on the environment external to them to keep them cool, the engine operating temperature varies greatly: the engine sitting at a stoplight in July and the engine making a coffee run on a cold December morning are both simply relying on the environmental temperatures to keep cool.

The design of air-cooled engines also leave a bit more room for expansion and contraction in the engine itself, since the temperature range is so broad. This primarily means that they are less efficient because they literally allow for more wiggle room. As such, it also means there’s a little bit of internal leakage which saps some of your engine performance.

Air-cooled engines are also very clean looking. Since they don’t have radiators and hoses and pumps, there is less in the way of the engine, allowing it to be viewed in all its glory.

On the other hand, liquid-cooled engines regulate their own operating temperatures by encasing the engine in a liquid (usually antifreeze or water) that is cooled by a radiator. The pump circulates the coolant from the radiator, around the engine, and then back to the radiator in an endless cycle of cool. The radiator relies on air streaming into it while the motorcycle is in motion to keep itself cool, but in case you’re sitting at a stoplight in July and the engine starts creeping towards the uncomfortably toasty range of the operating temperature, the fans will kick in  and will feed air directly into the radiator when the sensors read that the engine is getting too hot, keeping your engine from turning into a barbecue.

Since liquid-cooled engines have narrower operating temperatures — meaning that they operate at a more consistent temperature — they tend to be more efficient. Less expansion and contraction means more consistency, and more consistency allows for a more efficient and precise design. It also means they arguably last longer because they endure less wear and tear. However, you do run the risk of being put out of commission if a rock flies into your radiator while you’re riding at speed, which is very costly to replace.

Liquid-cooled engines are also quieter due to the fact that they’re encased in liquid because it muffles the sound. But don’t think that’s a bad thing. With increasingly stringent regulations on how loud a motorcycle can be, a quieter engine means that a freer-flowing exhaust system can be used (being a louder, better performing exhaust system).

Now for the issue everyone is actually concerned with: the looks. Air-cooled engines have fins. Typically, liquid-cooled engines do not have fins because they don’t serve a function on them. However, Triumph, in keeping with their love and respect for heritage, has kept the fins on their liquid-cooled engines. The fins don’t adversely affect the engines, but do give them a true retro look. So you don’t have to worry about sacrificing your vintage motorcycle looks if you go with one of the new liquid-cooled engines.

 

 

While purists and true retro enthusiasts may cry foul at Triumph making the transition over to liquid cooling or that they have sold out by joining the crowd, you can at least trust that they’re going to continue making great bikes that run just like the ones you’ve grown to love.

In the end, neither is necessarily better than the other. The air-cooled bikes have true heritage designs, and the liquid-cooled bikes have the efficiency of modern technology. Take your pick — you can’t go wrong.

One comment on “The Engines, They Are A-Changin’: A Comparison of Air-Cooled and Liquid-Cooled Engines”

  1. Mohd. Imran says:

    Great post. Loved the clarifications!

    I am planning to get the ’17 T100 Black. This one is liquid cooled and I was wondering whether it’s safer and less complex to just buy a used air-cooled one as I heard the more electronics you have on a bike the more problems you will be threatened with in the future. Is this the case with the new liquid-cooled Bonnies?

Leave a Reply

Your email address will not be published. Required fields are marked *