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Old 02-28-2009, 09:35 AM   #23 (permalink)
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Originally Posted by davidgrey50 View Post
A stupid question: Why couldn't an exhaust system (at least the cooler downstream parts) be made of aluminum. Weight is the enemy, and all that...
Structural integrity of the pipe itself aside; cost. Exhaust is a component where the steel can be very thin because the shape of the product is structurally sound (section modulus relative to the direction of loading i.e. vertical vibration). Aluminum would have to be thicker because it is weaker and it is more difficult to bend although it can be done. Weight savings would be reduced by added thickness, plus aluminum costs quite a bit more per unit weight.

The C5 Corvette Z06 used titanium exhaust pipe which was even lighter than aluminum would be plus can handle the heat as well as steel. It was even more expensive. While weight is AN enemy, in almost all vehicle applications there is a cost/benefit tradeoff that is attached to weight reduction and "exotic" unseen parts typically cost high and benefit few.
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