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

[Louis-Alain Richard]

Cody wrote :

 

Well excuuuuse me for using what I thought to be a moderately entertaining
analogy to help my point, which it seems you missed entirely. 

 

>No harm, that is part of an internet discussion.

 

The bottom line here is that there are many differences in the 10v and 20v
engines that change the acoustic properties. I could insert another analogy
about different size and length tubing in a trumpet vs a coronet, but I
guess that isn't acceptable. You have two distictly different cylinder heads
with a different number of differently shaped exhaust ports that couple to
differently shaped and sized exhaust headers. Different stuff makes
different results. 

 

>Indeed.

 

I would venture to say that the 'pulse' difference you hear has alot to do
with the exhaust header. The 10v engines use basically two different header
designs that I know of. The non-turbo engines use somewhat of a log style
header where the cylinder 1 header primary tube runs rearward and the rest
of the cylinders dump into that tube rather then having thier own primary
tubes. The the turbo 10v headers are halfway between a proper header and a
log - cylinder 1 gets it's own primary tube, but 3&4 and 2&5 share for at
leas parts of thier path to the turbo. Both of these designs have no pulse
tuning whatsoever which means that the pressure pulses of exhaust exiting
the engine will not reach the turbo at evenly spaced intervals. Some pulses
will be colliding and creating louder sounds, while other pulses might be
landing in a void and being muffled a little. The 20v's that I'm familiar
with have much much better header designs, especially the CQ bundle of
snakes header, but also the AAN style are designed so that each cylinder
gets it's own header primary that feeds into a collector. They aren't
precisely equal nor tuned length, but they are significantly better.

 


> Now, you are thinking exactly like me. Sound is tuned in the EM, and then
muffled by the rest of the system. No matter which exhaust you install, if
the initial sound is poor, the result will be louder but still the same
cheap note. 

 

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