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Re: SVO: Re: Some Ideas on Preformance Exhaust For The Turbo Coupe



On Mon, 17 Nov 1997, Dave Compton wrote:

> > He did say a 3"
> > down pipe would help but not as much as a bigger tailpipe/muffler
> > which needs to be changed first to make a down pipe flow better
> > anyway. 
> 
> I don't agree, but only have my observations to go on.  Granted both is
> better, but as exhasut gas cools it  needs less space.  That's why a stock
> system diminishes in size from front to rear. 

they do??  not saying that none do, but I have never seen one. Only times
I see it go down is in a y pipe on a V engine...
And I hav enever seen a pipe size change as drastic as 3" to 2.25". Thats
rejected.  how coem the outlet piping is not smaller on intercoolers? the
change in temp is high there too.

 Ergo,

what does ergo mean?

 make big tubing
> (downpipe) at front.  Yes, the rear will help too, but I believe that the
> improved compopnets contribution to poewr is almost equal.
> 

your saying that just having a bigger downpipe for about 40" of the system
is equal to having a bigger cat back, AND bigger mufflers? I would be
willing to bet that if you put a 3" downpipe(especially a crushbent one),
on a stock exhaust, you would be hardpressed to gain much of anything.
Want to know how much a stock down pipe affects flow by itself?  I have a
stock merkur pipe in the pinto that exits out the side right after the
ball joint, no muffler.  I will run the car with and without next time I
go to the track.  We'll see how much the pipe alone hurts performance.
But lets talk disturbances of flow.....
lets say you put on a 3" downpipe.  Right at the joint where the pipe goes
from the outlet of the turbos 2.25 inch to 3", there is a resistance to
airflow, that is not there with a stock pipe.  then the exhaust happily
flows thru the larger pipe, until we get to the point where it meets up
with your stock cat, or stock cat back.  thre is another decrease in flow
there, where the pipe has to drop down to 2.25" again.....And your running
the beutiful stock duals rite? well, that y connection there adds more of
a restriction. 
its a whole lotta reduction on flow.  made up for by the cooling of the
pipe? I doubt it.  
if the cooling affect helps so much, why do the nascar guys step UP their
header size as they go away from the head??  they should be going smaller
rite?
Like i said, I dont know the quantification of the cooling of the exhaust
and its affect on pipe size requirements, but it helps more than the
addition of a higher flowing, bigger muffler, especially with all the
resrtictions that system has...


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Scott
-71 Pinto, stock 2.3 turbo, 13.67@98, radials
	Big intercooler ON!
	T4 Compressor soon to be on!
-85.5 Escort, SOLD! 
-85 Merkur, let the modding begin! 
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