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Since it debuted in 1953, the Chevrolet Corvette has grabbed the materials spotlight. First with its innovative plastic body panels, later with dozens of other major body, powertrain and suspension components. The low-volume 2001 Corvette Z06 continues the tradition with the first major use of titanium in a mass-produced vehicle. It marks a new era for the space-age material, which until now has been confined to very limited use in automotive, mostly related to racing. But titanium isn't the only materials story for the '01 model year and beyond. In fact there's lots going on with steel, aluminum, plastics and the rest of the automotive materials menu. For a full rundown, read on.

Forty years ago, America's first astronaut heroes flew spacecraft wrapped in a space-age metal called titanium and drove Chevrolet Corvettes that were wrapped in fiberglass. Now, the updated 2001 version of the Original Seven astronauts' vehicle of choice is equipped with an exhaust system made of that same titanium that protected them from the high temperatures of orbital re-entry.

Although the titanium exhaust isn't the only material story on Chevrolet's new Corvette Z06, it is the most significant in terms of weight savings. The Arvin Industries (now ArvinMeritor Inc.) creation makes the most significant contribution to the Z06's increased horsepower-to-weight ratio, trimming 36 lbs. (16 kg) from last year's hardtop, which the Z06 replaces, and 117 lbs. (53 kg) from the standard Corvette coupe.

"It was totally a weight deal since exhaust systems are quite heavy," says Tadge Juechter, Corvette's total vehicle integration engineer. "It is very expensive, but it is a life-of-the-car system."

Mr. Juechter says the titanium exhaust system - which starts behind the catalytic converter, includes the primary muffler, exhaust pipe, secondary muffler and extends to the tips of the tail pipes - costs about twice that of its stainless steel counterpart.

Titanium, although plentiful in ore, is complicated and expensive to refine, produce and weld. Plus, it's several times more expensive than stainless steel, although cost is coming down.

It has been used in jet engines since the 1950s and in spacecraft since the 1960s because of its light weight and high heat and corrosion resistance. The same qualities make titanium attractive for automotive applications. The only hurdle is its price.

Arvin has been developing a titanium exhaust along with material supplier Titanium Metals Corp. for about seven years. The companies approached the Corvette team with the concept as an experiment. By using scrap titanium from other non-automotive products, and adjusting the thickness of the material, they were able to reach General Motors Corp.'s cost goals for the project.

In addition to saving weight, titanium gave advantages to engineers in fabrication and design, which enabled them to reduce exhaust backpressure, mainly enhancing high rpm gas flow. It also gave the Z06 a distinctive, more aggressive exhaust note than the standard Corvette.

Creating that high-powered exhaust is a V-8 powerplant with a new high-compression aluminum cylinder head and a modified aluminum engine block.

While the aluminum engine components save weight, the new thin-wall design cast-iron exhaust manifolds, which replace stainless steel on the new engine, add weight. But, says Mr. Juechter, "It was done primarily for flow reasons. Passages could be made in the right shapes and the interface between the head and manifold makes the transition smoother for the exhaust gases."

New pistons for the LS6 engine are cast from high-strength M142 aluminum alloy and are barrel shaped to withstand the new rev limit of 6,600 rpm, up from 6,200 rpm.

Another response to the power increase is that the aluminum metal matrix composite driveshaft had to be replaced with one of aluminum alloy 6061.

"It would have been more expensive to use a stronger metal matrix, so we went with a larger piece of aluminum," explains Mr. Juechter.

To save weight, the Z06 Corvette uses thinner glass in the windshield and back light. "The great thing about Corvette is that every part gets its own materials selection, then it is put together as a system," says Mr. Juechter. "This is another chapter in its history of innovative materials selection."

If you can't afford the Z06, the standard Corvette also has some new materials innovations for 2001, including a soft top for the convertible made of new fabric that cuts noise an additional 3.1 decibels. The innovation comes from Haartz Corp. and Collins & Aikman's Dura Convertible Systems. Haartz developed the "Twillfast MC" multi-ply composite fabric, which has never before been used for a convertible top.

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