Working with Metals: Titanium and Composites

Since the valves are much lighter in weight than stainless steel, the engines can run higher RPMs without danger of encountering valve float (when a valve moves so fast that its momentum causes it to continue opening even when it is time for it to close). A reduction in weight helps keep this from happening.

At Home with Titanium
So is there a future for titanium valves in your hot rod? Well they are probably available for your particular application, but for a price. As tough as titanium may be, it still lacks the strength and durability of the old standard steel valve. Titanium has a tendency deform where it comes into hard contact with other metals, and it galls, or sticks, when mating parts must continually slid across it.


In a racing engine that is not expected to last more than a few races, these drawbacks are entirely acceptable. In an engine that is designed to last a few hundred thousand miles though, they could begin to cause problems. A material like titanium is best suited for racing applications where extreme light weight and strength are priorities over cost and longevity.


Some other exotic metals that are used in aerospace are grouped in a category called super alloys. Super alloys are designed for high strength under high heat, such as what may be encountered in a jet or rocket engine. These materials are rarely necessary in automotive applications that are not involved in professional racing. They are typically heavy, and are designed to offer maximum strength under very high temperatures.

Composite Composition
As for exotic non-metals or composite materials, one of the most popular aerospace composite materials to make it into consumer use is carbon fiber. Carbon fiber fabric is infused with an epoxy that hardens much like fiberglass (or that dried gravy stain on your cotton shirt)—it is not carbon fiber alone that makes the material.