[urq] Why are the L5 Turbo engine sounds different ?

[John Cody Forbes]

> But how can we explain Andrew view, same exhaust but different head
> components ? 
> Anyone else has an explanation ? Other examples ?
> Any musician out there ? J
> 
> Louis-Alain

I think Huw is our resident acoustical expert ;-). C'mon Huw, lets hear your idea!

Think of it this way: The very source of the exhaust note is the bang of the combustion explosion inside the cylinder. You only get to hear the portion of that explosion that is still hapening when the exhaust valve opens. If you open the exhaust valve sooner you get to hear an earlier part of the explosion and you hear more of it if the valve stays open longer. If you also open that valve more you are going to speed up the finishing phases of the combustion process. Then take into account that all of these valve timing and lift changes are changing the way the pressure pulses move through the header you've got a pretty cut and dry explanation.

-Cody Forbes