exhaust size vs. temp Options

[ShadowFX]

lol yeah okay.. it sounds dumb but its for a physics assignment, would a bigger diameter exhaust have a difference on the exhaust gas temperature? if so, minor or major?

[SpedToe169]

Physics answer: Yes.

But not so mucn because the gas is expanding, it already does that a LOT when it leaves the cylinder. The biggest difference in temp could probably be attributed to the increased surface area for heat transfer due to the larger tube diameter. If you're really doing this for a physics class, its a pretty complicated problem to solve numerically. You have to know a lot more about the operating conditions of the engine to correctly solve it. You must define a control volume (where in the exhaust you're talking about) and have conditions for the gas flow through it. The engine must be in steady state operation (i.e. not speeding up or slowing down, not changing load, etc.). What level of class is this for?

Real world answer: Nope.

It won't make any difference unless your previous exhaust was waaaay too small and causing a lot of restriction on a turbo car. The pressure difference would not be great enough in any other situation to change the temperature a measureable amount.