Quote:
Originally Posted by serialk11r
If the whole thing is aluminum expansion wouldn't be an issue but I guess the headers see some high temperatures and that would be bad. However how much mechanical stress does the exhaust even go through? And how would it have corrosion issues when hot? Sorry if these are dumb questions I sorta don't see what's so bad about aluminum, steel doesn't seem to be any better  |
The expansion/contraction, coupled with its weakness as it gets hot (all metals have a curve about how their strength changes with temperatures, some drop off faster than others), and the vibration that the exhaust is subject too, means welds, and possibly the stressed bends are going to break.
This is even true with steel and stainless steel to a lesser degree, as seen by the use of flex sections and slip fitting to relieve stress on the joints. But stainless holds its strength better with temp.
As for the corrosion, maybe I worded it wrong. It's probably something more to do with the temperature of the stuff in the exhaust acting on the aluminum. This isn't something I have much experience with, though. But just think of chemistry, cold acid reacting on something, vs hot acid reacting on something. Aluminum doesn't really resist corrosion, it's that the corrosion on the outside ends up acting like a barrier.
That's the best I can do, sorry.