[DeTomaso] Famous Pantera 2000 RPM exhaust resonance

[John Taphorn]

Mike

Welcome back.  Hadn't seen you on the list recently.

Would like to let you know again how helpful your website is on jogging my 
memory when I am restoring this and that.  I can generally find the answer 
to my questions.

I appreciate your efforts - it is a great resource for the Pantera 
community.

Thanks
JT
----- Original Message ----- 
From: "Pantera Place" <panteraplace at hotmail.com>
To: "'DetomasoList'" <detomaso at realbig.com>
Sent: Sunday, September 25, 2011 2:24 PM
Subject: [DeTomaso] Famous Pantera 2000 RPM exhaust resonance


> As I've driven the Pantera more, I realized just by ear that the impact of
> the sound deadening work that I did was having a larger impact than I 
> first
> thought.   It definitely had an impact on engine mechanical noises, but it
> also seemed to be impacting the exhaust noise.
>
> To get a more precise measurement of the situation I did more DB sound 
> level
> testing today.  The idle DBa five feet behind the car it still in the 86 
> to
> 87 ranges, but to my surprise the interior sound is substantially reduced.
> The interior sound level at idle was 86 now it is about 80 (windows down)
> and around 75 with both windows up.
>
> Underway (windows down) in the 2000 RPM range it was 86 and now it is 
> around
> 80.  Windows up about 75.  What is most interesting the 2000 RPM harmonic
> doesn't really sound much quieter by ear.  Expect this is because the DBa
> filter does not pick up the low harmonic frequency like the DBc filter
> would.   Each 3 DB represents a doubling of the sound level.
>
> The windows up and down readings have a larger delta than they had before.
> The exhaust sound seems more remote now and external from the interior.
> This was all accomplished just by sheeting the back side of the removable
> fiberglass firewall cover with sound deadening material.  My car has the
> factory sound deadening material on both sides of the firewall but the
> engine hatch is aluminum with no deadening material.
>
> After I've run the sound deadening material for a while I'll be able to
> provide more information on its adhesion to the fiberglass, suitability,
> etc.
>
> Mike
>
>
>
>
>
>
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