Description:

Suzuki Bandit cools the engines with water for a long time, BMW is working on the water jacket for the boxer and the V2 of Moto Guzzi, the water is up to the cylinder feet. If the cooling fin soon become obsolete? MOTORCYCLE gathered information, opinions and predictions.


Fins do the same as the large ears of elephants: they increase the surface area for heat exchange, thus ensuring that a heated body can be cooled more effectively by the surrounding air. This is a simple technical problem, not more. Nevertheless, air-cooled engines that have properly cooling fins on the cylinders and their heads, for many people a matter of the heart. They are considered beautiful, simple and original.

Whether in the Porsche 911, the Ducati Monster or the Yamaha XJR 1300th Even their loud crackling and popping during cooling has emotional value.

Why is water cooling?
This water can be used as cooling medium, the air and the cooling fin intended job done much better. It absorbs the heat faster and faster they are back again, so we cool off while swimming in 24 degree water, while walking in the same hot air but more likely to overheat as a shiver. Applied to the engine technology means that a water cooling system can derive much more heat than even a very clever designed air cooling. Also, oil is on the dissipation of heat is only about half as good as water. The most vulnerable areas to heat the spark plugs and exhaust ports of an engine in an extraordinary degree of benefit of water cooling, and this has far-reaching consequences. If the heat is dissipated, a motor can produce more of it once. So the designers optimize the charge cycle, the compression, ignition timing and the combustion process and increase the speeds. In short: you increase the performance. In addition, an efficient water cooling improves quite significantly the smoothness, reliability and durability of an engine. The liquid cooling jacket absorbs the hard mechanical noise, compensates for temperature differences between individual areas, allows for tighter piston clearance, reducing emissions and wear. On the other hand, is associated with the installation of water-cooling water pump, thermostat, radiator, electric fans and a multifaceted Schlauchgeschlinge, as aesthetically satisfying only in rare cases. If it does, these components are hidden rather than revealed.

Favorable conditions in motorcycles.
Because bikes are light and the wind blows through, can meet some of them with air-cooled engines, both the current noise and emission standards as well as the dynamics requirements of today’s customers meet. Those who do not just want to be successful in racing, has around 100 hp enough reserves for all traffic situations. In the vicinity of the 100-horsepower limit most of the major air-cooled motorcycle engines is currently, they need to output of 95 to 110 hp between 1079 Ducati Monster 1100 Evo and 1251 cm ³ (Yamaha XJR 1300). The 110 PS (R models), but especially the 133 hp (HP2), the BMW from 1170 cm ³ DOHC brings the two-cylinder boxer, may be regarded confidently as engineering feat in this environment. This was confirmed by a Porsche engineer who is familiar with the last air-cooled six-cylinder boxer-house 993-series still the best.

“There you go, but goes with cooling fin,” you might say now. It’s that simple but not yet. If conditions worsen, air-cooled engines behind sweeping panels work, heavy touring bikes to drive with a full load for long highway stretches, then balance and structures with a lower specific heat capacity at the edge of collapse. Not coincidentally Piaggio Development Minister Romano Albesiano falls first and foremost a tour a motorcycle when he area of ​​operation of a future, water-cooled engine Guzzi outlines. The rear cylinders of Harley-Big-Twin engines and Freedom of Victory, which are used in Touring models would probably sing a dirge, if they could. Harley-Davidson will then work with all the tricks to the American tradition, remain true to engine.

As with Air / Suzuki engines happy memory from below the piston heads are sprayed with cooling oil, and the Touring models are the only Big Twin support an oil cooler in addition to hitzeabstrahlenden dry sump reservoir. The thermal management is so very much that the rear cylinder will automatically shut down just before the heat death. And just in case you have still the water-cooled engines of the V-Rod series. Ducati veteran Gianluigi Mengoli who mitkonstruiert under the aegis of Fabio Taglioni already on the vertical shaft engines from Ducati is, readily admits that the two-valve V2 of the Monster 1100 and Hypermotard 1100 Evo Evo is an Air / oil engine actually. In the hot zone around the spark plug flows enlarged section oil flow past the additional internal cooling fins, stuck in each cylinder instead of two oil lines to the heads as before, only one, the oil cooler was also increased. We see that the pure doctrine of air-cooled, rich ribbed engine without special heat exchanger obsolete with the motorcycle engine.

Air cooling as a cultural problem.
That the same physical conditions in different cultures are interpreted very differently, the example of Japanese engineers. While working with their European and American colleagues in detail and with all the tricks in order to exhaust the cooling air further, they have a strong need for security. Among the Japanese motorcycle manufacturers, so tell insider that there was a gentlemen agreement to comply in terms of exhaust and noise emissions set ourselves, very strict limits to the policy not to provoke further restrictions. Therefore needs a Honda CB 1300 with 116 HP from 1284 cm ³ a water-cooled engine, the slick surfaces of the fin even appears as a decorative element. The retro bike CB 1100 with classic air-cooled four-cylinder may develop just 88 hp. Because its market opportunities in the PS-drenched Europe with this performance are too low, it is offered here does not arise. Kawasaki admits the newly opened W 800 hp to do only 48, but they still exported to Europe. “48 PS have enough time, too,” comment many W-800-fans this throwback to old English parallel twins.

Preliminary Conclusions:
Yet to decide the application and the maximum power of a motorcycle engine, the question of cooling fins or water jacket. To about 100 hp is enough for plenty of air cooling capacity. However, when the emissions standards are stricter and the durability of the emission is fixed by law (see page 102), the designers must make fullest potential, even the water-cooled motors. The effort to maintain air cooling and cooling fin is then improve dramatically – not a favorable outlook.