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Breakthrough Carbon Fibre Auto Manifold

06 January 2006

What is claimed to be the first auto intake manifold ever moulded from continuous carbon fibre-reinforced thermoplastic opens up new possibilities for such composite mouldings in more intricate, complex shapes.

The lead-off model in the line, made for the popular Honda H22 engine, is 75% lighter than the stock metal part it replaces and delivers 13 HP more than current aftermarket manifolds. It was made using the patented Diaphorm moulding process, which features low pressures and inexpensive tooling and machinery.

“Weight savings and power gains in the Honda manifold show what can be expected of continuous fiber reinforced composites in more sophisticated shapes,” says Robert M. Miller, president of Diaphorm Technologies. “The piece represents a breakthrough in composites technology on several levels – design, application and processing.”

The manifold’s weight saving stems from the composite’s lower density and higher strength-to-weight ratio compared to aluminium. The power gain stems from a larger internal volume than the stock part as well as an improved air flow design due to the intricate free flowing shape. Both improvements lead to delivery of more air/fuel mixture per stroke to the engine.

The manifold line, along with other carbon fibre performance auto products in the pipeline, will be marketed under the FiberTuned brand name. Diaphorm produces the manifold from two 60-40 carbon fabric-nylon mouldings joined by adhesive, then bonds in the mounting plate and injection ports. Reinforcing material is biaxial stretch-broken carbon fibre. Both mouldings involve much more complex shapes than have been seen to date in continuous-fibre reinforced thermoplastic mouldings. They feature aspect ratios up to 8:1, compound 3-D angles without cutting the fibres or darting the fabric yet with corner radii down to 1/16 in. “Heretofore, you could find such intricate shapes only in one off custom hand lay-ups,” says Mr. Miller. “Here we’re doing it in an efficient, repeatable production environment suited to medium to high volumes.”

“This manifold demonstrates how part designers can take advantage of advanced lightweight, durable materials, assured that the part can ultimately be cost effectively manufactured in volume,” says Mr. Miller. He added that the Diaphorm process is ideal for structural composites in small to medium lot sizes. Lower setup costs and relatively low-pressure processing are said to yield per-part costs that can be 20 to 70% lower than compression mouldings in comparable lot sizes.