[Tigers] X-over pipes

[Steve Laifman]

Owain,

With a V-8 the firing order alternates between left and right sides, as 
does a V-6. With dual exhaust systems this creates "pulses" of exhaust 
gas which differs between banks.  Some firing orders are not left-right 
uniformly.

The exhaust in each of the dual exhaust pipes is in "pulses", out of 
phase with each other.  This leaves a lower pressure space between each 
bank exhaust.  The X-Over connects these banks for the sole purpose of 
filling the "voids" from one out-of-sequence bank to the other. This 
should make the passage of gases more uniform between the banks, and can 
actually reduce noise, as well.  The sound may be mellower.

Many of the Sports and Muscle cars come with this pipe from the factory.

Interestingly enough, my '54 Jag XK 120 straight six had dual headers.  
They were split into 3 cylinders each and parallel pipes were run into a 
single muffler with twin fittings for the "banks".  The same rationale, 
except the "mixing" occurred inside the straight dual pipe mufflers.  
The harmonic sound was one of the best, and mellowest, I have ever 
heard.  The harmonic vibrations were transmitted through the floor 
boards to the driver's seat (LHD). Great!  In latter years they used 
separated mufflers, and that thrill was gone.

The Ferrari Testa Rosa (red head) was "straight pipe" exhaust with no 
mufflers (this was a competition car.)

Standing next to one when the throttle is pressed could tear out your heart!

Just rambling on the subject of why we like "pipes".  Listen to the Bill 
Cosby 33 1/3 album about his Cobra.

Steve

___
Steve Laifman
Editor - TigersUnited.com
<http://www.TigersUnited.com>



Owain Lloyd wrote:
> pardon my ignorance.  what is the purpose of a crossover pipe between
> the exhausts, anyway?