this maybe a dumb question but why don't they make exhausts out of aluminum?

 

Probably because it's harder to weld aluminum and aluminum would also rust. Stainless steel resists rust pretty well.

 

Aluminum will not rust , Bad answer, Aluminum will distort or melt at lower tempts than stainless steel. Rotory engine exhaust is hotter than a piston engine exhaust . The standard exhaust materal for most piston cars ( aluminized steel thin wall tubeing ) will not last long at the higher temps the rotor engine puts out . Show me rusted Aluminum . Rust is iron oxide .

 

I agree that rust was not a good reason not to use aluminum (since it doesn't rust), but it does corrode. That corrosion may be as good a reason as any not to use it. It also expands too much under heat and would melt or at least get soft (and probably severely distort) at exhaust temperatures.

-Max

 

sounds about right

 

The melting point of pure aluminum is 660 degrees C. Thats 1220 degrees F. Is the exhaust really that hot?

 

Piston engine exhaust can go about 1200 degrees . A rotary can go 1800 degrees

 

You learn something new every day.