Moto Guzzi Concept Inconel Exhaust

Kevin Ash

Pictures: Kevin Ash (click on images)

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Another innovation on the Guzzi concept bikes is the use of space age material Inconel for the exhaust pipes.

This is an alloy of mostly nickel (up to 73 per cent) with chromium (up to 25 per cent) and other metals added in smaller amounts to fine tune the material`s properties. These can include, aluminium, iron, molybdenum, manganese, titanium as well as non-metals silicon, carbon and phosphorous.

Inconel`s especially useful properties are exceptional stability at high temperatures and a very high resistance to corrosion. This is why it is used for pipework and other components in many chemical processes, and also for turbine blades in jet engines, and as on the Guzzi, in the exhaust systems of Formula One cars.

Because Inconel is strong and stable even at hot exhaust gas temperatures the Guzzi`s pipes can be made thinner than conventional steel or even titanium ones, which means the system is lighter. In addition its resistance to corrosion is useful cosmetically and also means very thin pipe walls don`t matter as corrosion won`t eat its way through.

The difficulty with the material is that it is very hard to machine. It work hardens very rapidly, meaning that if it is bent for example, it immediately becomes much harder and stiffer, so any further bending demands a much greater force and is more likely to fracture the metal than change its shape further.

For the same reason Inconel quickly blunts or breaks cutting tools, so it is often cut using very high pressure water jets.

The corrosion resistance is due to the rapid formation of a very non-reactive layer of oxide over the surface of Inconel (which is a trade name). The same happens with aluminium, but in Incocel`s case the oxide is even more resistant to the effects of salt, air, water and so on, and acts as a very effective barrier to corrosion for the main part of the material.

* 2009 Milan Show Moto Guzzi Concept Bikes
* Moto Guzzi Concept Heat Pipe Cooling System