[DeTomaso] ANSA mufflers

[Pantdino]

Mike, the law regarding relative resistances uses the radius, not the sq in size
So take half the diameter of the inlet pipe, multiply that by itself 4 times  (for example, 2 to the fourth power = 16), and you will get a number (X).

Then do the same for each of the "cutout" holes the exhaust gas can flow thru and divide by two because there are two of them.   This will give you a number. (Y) The relationship between these numbers will tell you the relative restriction of your two holes compared to the one larger one.  It will be Y/X, where Y will probably be bigger than X and tell you by what factor the two outlet holes are more restrictive than the inlet.  

I'm not sure how one would add a factor for the many small holes.  You could calculate the resistance for a 3/32" hole and multiply by 210 but I'm not sure where to go from there.

If I were you I would convert to millimeters to make the calculations easier.  Multiply the decimal expression of inches by 2.54 to get mm.  So 3/32" = 0.093" = 0.24mm approx

I'm not an engineer but this is my understanding of the mathematics involved.  
So Mike (either or you), don't blow a fuse if this is wrong. :-)

Jim





-----Original Message-----
From: Pantera Place <PanteraPlace at hotmail.com>
To: 'Pantdino' <pantdino at aol.com>; detomaso at realbig.com
Sent: Sat, May 21, 2011 6:48 pm
Subject: RE: [DeTomaso] ANSA mufflers



Jim,
 
Thanks for the engineering info on the perforated pipe.  I believe the inlet pipe at the front of the muffler has about 2.074 sq. in. of area.  The estimated 210 3/16” holes in the perforated main pipe total about 5.88 sq. in. of area plus the new cut outs I made.  Each cut out is about 1.25 sq. in. for a total of 2.5 sq. in.  Any ideas on the calculations for the flow restriction of the main pipe with the new cut outs?  I must be getting close to exciding the inlet pipe restriction. 
 
I’ve thought about a sound meter, I may need to follow-up on that.  
 
Mike            
 
From: Pantdino [mailto:pantdino at aol.com] 
Sent: Saturday, May 21, 2011 8:39 PM
To: panteraplace at hotmail.com; detomaso at realbig.com
Subject: Re: [DeTomaso] ANSA mufflers
 

Mike,  

 

the resistance of airflow thru a tube is inversely proportional to the fourth power of the radius-- so if you double the diameter of a hole the resistance decreases to 1/16th. So yes, the resistance thru all those little holes is much greater than thru a single  large hole.

 

What you describe regarding being disappointed with new mufflers being too quiet is why I have not replaced the rusted-out, ratty-looking Ansas on my car.  I like the sound and that is more important to me than appearance.

 

Do you have a sound level meter?  You can get one at Radio Shack very inexpensively.  It would be interesting to see what levels you get behind your car compared to a GTS, Hall, and other systems.

 

Jim Oddie



 

 

-----Original Message-----
From: Pantera Place <panteraplace at hotmail.com>
To: detomaso at realbig.com
Sent: Sat, May 21, 2011 2:57 pm
Subject: [DeTomaso] ANSA mufflers

I've been working on a series of modifications to my ANSA mufflers to
improve the exhaust flow and relieve back pressure.   The latest work is at
the bottom of this page http://www.panteraplace.com/page200.htm 
 
 
 
Mike 
 
 
 
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