[DeTomaso] ANSA mufflers

[wkooiman at earthlink.net]

Pie are round, but pi r squared = area (i.e. flow) pi x diameter=circumference, which should reflect drag.

Wait a minute.  I just had a vending machine pie, and it was rectangular, so I guess not all pie are round.

What wasn't mentioned is how this impacts the sound.  My bet is the bigger the hole, the deeper the sound.

-----Original Message-----
>From: Pantera Place <PanteraPlace at hotmail.com>
>Sent: May 23, 2011 5:44 PM
>To: 'Pantdino' <pantdino at aol.com>, detomaso at realbig.com
>Subject: Re: [DeTomaso] ANSA mufflers
>
>Jim,
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>Thanks for the detailed calculations.   I believe the perforated holes are close to 3/16”.   Any math wizards on the forum that could run the numbers?   The two cuts in the main pipe are 1” X 1.25”.
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>Mike
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>From: Pantdino [mailto:pantdino at aol.com] 
>Sent: Monday, May 23, 2011 1:02 AM
>To: PanteraPlace at hotmail.com; detomaso at realbig.com
>Subject: Re: [DeTomaso] ANSA mufflers
>
> 
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>Mike, the law regarding relative resistances uses the radius, not the sq in size
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>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).
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>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.  
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>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.
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>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
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>I'm not an engineer but this is my understanding of the mathematics involved.  
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>So Mike (either or you), don't blow a fuse if this is wrong. :-)
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>Jim
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>-----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,
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>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. 
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>I’ve thought about a sound meter, I may need to follow-up on that.  
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>Mike            
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>From: Pantdino [ <mailto:pantdino at aol.com?> mailto:pantdino at aol.com] 
>Sent: Saturday, May 21, 2011 8:39 PM
>To:  <mailto:panteraplace at hotmail.com> panteraplace at hotmail.com;  <mailto:detomaso at realbig.com> detomaso at realbig.com
>Subject: Re: [DeTomaso] ANSA mufflers
>
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>Mike,  
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>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.
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>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.
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>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.
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>Jim Oddie
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>-----Original Message-----
>From: Pantera Place < <mailto:panteraplace at hotmail.com> panteraplace at hotmail.com>
>To:  <mailto:detomaso at realbig.com> 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> http://www.panteraplace.com/page200.htm 
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>Mike 
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