The intake charge pipes for the motorcycle were fabricated from carbon fiber. This composite material allows for a pipe of significantly lower weight than a steel or aluminum pipe while maintaining the same strength characteristics. Carbon fiber also offers far better insulation properties, so the intake air does not absorb any heat as the pipes travel near the head of the motor, as required by packaging.
To fabricate these pipes, the lost foam technique was utilized. To do this, the pipes were laid out in extruded polystyrene foam(EPS), in this case a foam wreath.
Figure P1: EPS piping
Figure P1 shows the EPS tubing cut to shape and mocked up in location on the bike. After a final shape is established, the pipes are wrapped in 4 layers of coaxial woven carbon fiber.
Figure P2: EPS pipe wrapped in carbon fiber
Figure P2 shows the pipe with the carbon in place. As each layer is added, a high temperature epoxy resin is applied, fully saturating the carbon fiber. Eventually, this resin will cure into a solid form, reinforced by the carbon fiber fabric. To ensure maximum strength, the pipe with the resin saturated carbon fiber was wrapped in a heat shrink tape. This squeezes out excess resin and any air bubbles caught between the layers of carbon fiber. It also ensures a solid, even pipe is made so that it is free of air leaks.
Figure P3: Charge pipe unwrapped
After the resin has fully cured, the heat shrink tape is removed from the pipe, leaving a final high gloss surface finish and strong, solid pipe as seen in figure P3. At this point, however, the pipe is still full of foam. To remove this foam, acetone or gasoline is poured into the pipe. Polystyrene foam was chosen originally for this application as it is soluble in gasoline and acetone. The foam dissolves away, leaving a light weight, strong, hollow carbon fiber charge pipe in complex shapes that would be difficult to otherwise mold and fabricate.