DeTomaso Mailing List: August 97, Message #121
     



From: pantera@shiseis.com (Shane F. Ingate)

Subject: Pantera noise & Laguna Seca dB limit

Date: Mon, 4 Aug 97 11:03:29 PDT



All,

	Yesterday (Sunday), San Diego Panteras staged a "noise-level"

test at San Diego Jack Murphy "Qualcomm" Stadium autocross meet.

This was staged along with tech-inspection for those participating

at the Ferrari Club day at Lagus Seca, after the Historics.  We had

an interesting selection of Panteras with disparate exhasut/muffler systems,

so it was fun to listen and measure the different exhaust notes.



	We staged a couple of tests, each with with the Radio Shack

digital meter 50' perpendicular to the motion of the car, and asking the

drivers to pass with as many revs as they could muster in 1st, 2nd and

3rd (in my car, this equated to redline in 1st, 5000 in 2nd and 2500 in 3rd).

Our meter has not been calibrated, so there may be some errors in the system.

I present the highest readings we obtained for the runs.



	There are several ways of using the meter; one can use "A" or

"C" weighting (corresponding to frequency range, 50-30,000 Hz and

500-30,000 Hz respectively), and "slow" or "fast" response, which averages

the sound lever over a long or short time period, respectively.

We started out using the C weighting with fast response, and then

after a speaking with the local SCCA folk, used the same system

as do the SCCA, namely A weighting with slow response.



	The muffler systems ranged the whole gamut, from a 180-degree

header with welded on tube resonators and Super-Trapp plates (Alan

Fosters GT 4), GTS headers and early stock mufflers (mine),

big-bore headers and later stock mufflers (Lee Youngflesh), a hybrid

system of big-bore headers and 1 big-bore muffler and 1 later stock muffler

(Daniel "we are experiencing technical difficulties" Jones) and stock

headers and later stock mufflers (Brock Tella).



	So how did we go?



Who				C weight/fast	A weight/slow

-------------------------------------------------------------

Foster				-		92.3 dB

Foster (1st @ 7000rpm)		-		97

Ingate				99 dB (ouch)	90

Jones				93		85

Youngflesh			90		84

Tella				90		84



	The problem being that we have subsequently learned that the sound

level at Laguna Seca is measured using A weighting with a fast response.



	Sigh, guess we gotta do it again.



	At least my car passed tech!  Ceya in Monterey!



	Shane Ingate in San Diego



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