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10-20-2014, 05:44 AM
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CC Member
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Join Date: Apr 2014
Posts: 103
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Not Ranked
db measurements sidepipe FIA
Have anyone done any measurements of the noise on their ERAs?
The Norwegian regulations for amateur built vehicles dictates the vehicle must meet a European sound regulation. The maximum sound level is 87db.
The microphone is to be placed 20" from the exhaust outlet, at a 45 degree angle in the direction that puts the mic the furthest away from the body.
Throttle is applied to bring the engine up to 3/4 of peak power rpm, or if that rpm is not available, 3/4 of engines maximum contructed? rpm. Say rev limiter anyone?
I´m guessing open pipes are definitely out the window, how quiet are the quiet ones at say, 4000 rpm for a 289/302/331?
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10-20-2014, 08:25 AM
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CC Member
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Join Date: May 2001
Location: California,
Ca
Cobra Make, Engine: NAF 289 Slabside Early Comp Car with 289 Webers and all the goodies. Cancelling the efforts of several Priuses
Posts: 6,592
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Not Ranked
Sort of makes it sound like a 66 Mustang on the showroom floor. (:
__________________
Rick
As you slide down the Banister of Life, may the splinters never be pointing the wrong way 
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10-20-2014, 01:09 PM
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Half-Ass Member
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Join Date: Jun 2005
Cobra Make, Engine: ERA #732, 428FE (447 CID), TKO600, Solid Flat Tappet Cam, Tons of Aluminum
Posts: 21,897
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Not Ranked
Quote:
Originally Posted by J.Jensen
Have anyone done any measurements of the noise on their ERAs?
The Norwegian regulations for amateur built vehicles dictates the vehicle must meet a European sound regulation. The maximum sound level is 87db.
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That's going to be a toughie.... I have the "quiet type" pipes on my ERA and she idles at just under 95 decibels.
Last edited by patrickt; 10-31-2016 at 11:50 AM..
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10-20-2014, 03:29 PM
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CC Member
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Join Date: Apr 2009
Location: Little Rock area,
AR
Cobra Make, Engine: ERA Street Roadster #782 with 459 cu in FE KC engine, toploader, 3.31
Posts: 4,483
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Not Ranked
87 db is pretty low. You would probably have to use a reverse flow undercar mufflers with a side exit and then I'm not sure it can be met. Those regulator guys can kind of put a damper on fun.  |
10-20-2014, 05:57 PM
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CC Member
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Join Date: Apr 2014
Posts: 103
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Could the pipe be filled with some type of wool or something to muffle it just for the inspection and take the pipe off and remove it after the paperwork is done?
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10-20-2014, 06:43 PM
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Half-Ass Member
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Join Date: Jun 2005
Cobra Make, Engine: ERA #732, 428FE (447 CID), TKO600, Solid Flat Tappet Cam, Tons of Aluminum
Posts: 21,897
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Not Ranked
Quote:
Originally Posted by J.Jensen
Could the pipe be filled with some type of wool or something to muffle it just for the inspection and take the pipe off and remove it after the paperwork is done?
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Maybe. I've seen some small block Cobras that were pretty quiet (too quiet). Since you're asking about small block FIAs, that might work to get you by. |
10-21-2014, 07:58 AM
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CC Member
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Join Date: Nov 2003
Location: New Britain,
CT
Cobra Make, Engine: Size 10 Feet
Posts: 2,993
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Not Ranked
Generally, the 427 exhaust is considerably louder than the FIA. If necessary, however, there is quite a bit of room in the FIA down-pipe where some extra silencing material can be positioned. Permanently, of course.  |
10-21-2014, 08:05 AM
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CC Member
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Join Date: Apr 2014
Posts: 103
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Not Ranked
God no, permanent would suck. But a downpipe could maybe be replaced for an open one - to keep the silent for reinstallation for the annual inspections (every two years)?
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10-28-2014, 09:31 PM
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CC Member
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Join Date: Jun 2007
Location: Caldwell,
NJ
Cobra Make, Engine: ERA 427, 482ci sideoiler
Posts: 138
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Not Ranked
If the government inspection is going to incorporate an analysis of the exhaust gases, as well as decibel output, then you will need to retune the engine for the test. So, have a street exhaust/tune and track only exhaust/tune, that you can switch between. If you are not experienced with converting between the two, have the company you pay to do the tuning/exhaust work show you how to convert between the two.
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10-29-2014, 02:11 AM
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CC Member
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Join Date: May 2006
Location: Portland,
OR
Cobra Make, Engine: ERA FIA, 1964 289->Webers
Posts: 3,689
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Not Ranked
My 289 has fairly low compression & would probably be considered quiet next to most. I have the sidepipes with the "cherry bomb" style center piece. If you keep the RPMs down its reasonable. @ 3000-4000 rpm it's not going to be quiet on any meter.
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ERA FIA 2088
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10-29-2014, 03:23 AM
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CC Member
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Join Date: Apr 2014
Posts: 103
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Not Ranked
Quote:
Originally Posted by ERA174
If the government inspection is going to incorporate an analysis of the exhaust gases, as well as decibel output, then you will need to retune the engine for the test. So, have a street exhaust/tune and track only exhaust/tune, that you can switch between. If you are not experienced with converting between the two, have the company you pay to do the tuning/exhaust work show you how to convert between the two.
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No exhaust gas analysis. Only requirement is no colored smoke on acceleration  |
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