[s-cars] exhaust diameters

[Chris Covington]

On Fri, 8 Sep 2000 qshipq at aol.com wrote:
 
> After doing a couple dozen of these systems over the years at my shop, the 
> dual 2.5in system definitely makes a difference over a 3in.  I've tested a 
> couple back to back, and the dual 2.5 in terms of flow and performance is the 
> meow.  The math would show that a 4.0in single would flow even more, someone 
> else will have to btdt, I've seen that on a car (buick GNX), can you say 
> stove pipe?
> :)

How about dual 3" or 2.75"?  If 4" is too big to fit on our cars, these
should be doable.  

Heh, or triple 2.5" since we don't really have true dual exhaust anyway
(unless you have a new S4 or something with a V engine or two
'downpipes').  

I have to wonder about this whole penchant for "dual" exhaust systems.  
We have inline engines.  Any muscle car guy, like me, would laugh when you
say our Y systems are "dual exhaust."  Do that simple volumetric math,
triple should be even better right?  Triple exhaust anyone? ;)  

But seriously, since there is a Y, a "split" in the exhaust, those
mathematical formulae shouldn't apply for our I-5 engines.
They are intended for two sources, not only one.  Yes, X and H pipes help
on true dual exhausts, but these are entirely different than one pipe from
an inline engine splitting into two.  Any Thermo Engineers / MSEs here?
I'm a Computer Engineer, only took thermo, but I'd like some perspective
on this.  

If that is true, and Y splits in exhausts are so great - then why don't
all the high po V8/V6 etc. guys have quad exhausts when they have no
expenses to spare, and no fabrication that can't be done?  The weight, I'm
sure - and we're adding more with "dual" exhausts on our 200s.  Something
to consider, along with this "math" that's being offered.  Maybe that's
why there aren't many "dual" systems out there.

Chris
'91 2cq