Why the Future of Air Cooled Engines Isn’t Too Hot

Retro styled bikes are the current big thing in the motorcycle world. The Ducati Scrambler has been a huge sales success with other manufacturers such as Triumph and Moto Guzzi also riding on the popular resurgence of old school charm and character. Ironically though, this increasing popularity of retro bikes comes at a time when their power plant of choice – the air-cooled engine – is under increasing pressure to remain a viable option.

The death sentence for air-cooled engines was handed down in 1999 when the Euro 1 emission standard was introduced. European emission standards were brought in to reduce all that nasty stuff that finds its way out of a vehicle’s exhaust – carbon monoxide, hydrocarbons and nitrogen oxide. Today, the Euro 3 standard is the requirement that manufacturers must meet in the EU and has been so since 2006. Until now, motorcycle companies have been able to keep the emissions of air-cooled engines below the threshold without investing too much money to do so. But come next year, that all changes.

Why the Future of Air Cooled Engines Isn't Too Hot

The Ducati Scrambler’s engine is currently only good for Euro 3 standards

Beginning in January of next year, the Euro 4 standard will come into effect and that will see a reduction in allowed emissions of carbon monoxide, hydrocarbons and nitrogen oxides of nearly half. From Euro 1, total emissions allowed has been reduced by up to a massive 94%. In other words, in the space of 17 years manufacturers have been asked to nearly eliminate the pollutants from fuel burning engines. It’s akin to being asked to boil water without any steam being made.

Thus, air-cooled engines (alongside two-strokes) are casualties of such tough measures. Air-cooled engines suffer in comparison to water cooled motors due to the way they work. One reason is because air-cooled engines take time to warm up, meaning it can be some minutes for the bike to run optimally. Unfortunately (and perhaps stupidly), emission testing is done on immediate engine startup, hence air-cooled engines are already running at a handicap.

The other issue is that air-cooled engines just aren’t as good at having their temperatures controlled properly. The very nature of water cooled engines means that their temperate is generally uniform throughout whereas an air-cooled motor can have different temperatures throughout – this means it is much harder to achieve optimal fuel burn and hence emissions will generally be higher.

This impending crunch for air-cooled technology has all but seen them disappear from showrooms. Models that are currently for sale will be allowed to remain so until the end of 2016 but after that, all new motorbikes sold must meet Euro 4 standards. That means Moto Guzzi, Royal Enfield and Harley-Davidson (bar the V-Rod) – whose entire range incorporates air and/or oil cooled engines – will need to make some big changes in order to be able to continue to sell motorcycles in Europe come 2017. It also means that BMW and Ducati will have to make modifications to their Scrambler and R nineT.

Why the Future of Air Cooled Engines Isn't Too Hot

Harley-Davidson’s hybrid air and water cooled technology

Some of those changes are already underway. Harley-Davidson is at the front of the curve here. Under their “Project Rushmore” development, HD introduced a hybrid system of air and water cooling. The technology uses radiators that are hidden as best as possible which is used to cool the cylinder heads of the engine. Unlike solely water cooled engines, the system remains largely invisible. BMW Motorrad did a similar thing with their R1200GS which uses radiators that you wouldn’t even notice unless you looked hard.

Manufacturers will be able to rely on such technology in order to keep within Euro 4 guidelines – if they’re willing to invest the money to do so. It’s highly likely that Moto Guzzi will follow the lead of Harley-Davidson and BMW. Whether Ducati does so for just a single model – the Scrambler – remains to be seen although given that their intention is to make Scrambler stand out as a brand of its own, it seems likely they have something in store to keep it going from 2017 onward.

The other alternative is for manufacturers to use smaller air-cooled engines. Because the emission regulations are all about actual emissions and not as a percentage of total engine size, it means smaller engines will more easily meet the requirements because they require less fuel. How small, though? Well, if we use the current Ducati Scrambler as an example it will need to be smaller than 803cc as it only meets Euro 3 guidlines. It may mean only the likes of Royal Enfield and their circa 500cc range can remain unchanged.

That is until 2020, when Euro 5 will be introduced and new air-cooled powered motorcycles will go the way of the VHS and cassette tapes – things you can only buy second hand.

Why the Future of Air Cooled Engines Isn't Too Hot

Moto Guzzi’s entire range uses air and oil cooling for its bikes, which won’t be enough to pass Euro 4 guidelines

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  • gdbizns

    Well, water does actually cool down too, it even freezes! It takes a while to heat it up, and first you have to heat up the engine, then the water… So, if measures were taken of air-cooled and watercooled cold engines, they would be about the same… You can’t measure emissions of a cold engine, the cat won’t work until heated up a little (Same thing goes when you whack the throttle open, even on a well tempered engine). But, in former days there was a saying that an aircooled engine needs to have larger tolerances because it must work in higher temperatures than water-cooled engines. And that’s why the emissions would be higher… But… When oil-cooling was added to critical points, this seems to be not a problem any more… I’m no specialist but would not be surprised to learn that aircooling would some day make a comeback as euro-whatever-compliant, now when we have this modern technical knowledge on hand. But. Factories just like to produce cheap stuff… More profits. They like to cheat, too (like they did at VAG)…

  • White Rabbitt

    Any and all persons that advocate emmission standards for motorcycles should be killed dead. PERIOD