Connect, no.129, March - April 2004, p.8

Exhaustive testing proves Barrikade benefits

Temperature is plotted against time as the exhaust warms up

Motorcycles have changed over the past fifteen years with increasing emphasis on speed and power. In the past motorcycles were used purely as a form of transport but as car prices fell, the motorcycle industry needed to find other ways of enticing its riders.

The outcome was the birth of the superbike capable of speeds of 160mph on a racetrack and acceleration of 0-60mph in less than three seconds. This can be achieved by a variety of methods, but one of the most cost effective is fitting an after-market exhaust.

These exhausts consist of a perforated internal tube encapsulated in either glass fibre or a mineral wool to reduce noise and bring the outside temperature of the exhaust below 80°C. Because these exhausts have minimal or no baffle plates, the exhaust gases are allowed to flow without being restricted. This allows the engine to breathe easily and gain an increase in power and performance.

However, there are problems with some exhausts as the insulation material breaks down, gets caught in the airflow and is released into the atmosphere. This contributes to air pollution and, some believe, exacerbates respiratory problems such as asthma and bronchitis. Because of this, the rider needs to repack the exhaust, approximately every eighteen months, with new glass or mineral wool. If this is not carried out the sound will be above the legal requirement and the outside temperature of the exhaust will rise above 100°C causing damage to the bike and possibly the rider.

Barrikade^TM, TWI's patented heat-insulation material, is currently being assessed to overcome these problems but still give the required performance. It looks very promising with the ability to be moulded into complicated shapes and give the required protection without releasing fibres into the atmosphere.

Because Barrikade is so versatile, the density can be altered, allowing the sound attenuation of the bike to be tuned. Also, in the future, additive could be added to use this material as part of the catalytic emission control of the engine.

Being able to place this material exactly where you need it also gives greater freedom in the design and the shape of the exhaust. Barrikade could also be used to give additional performance enhancements in parts such as cyclones and venturi tubes to give even greater performance or improve the efficiency of the engine.