Thinking about lower DB

[markbe01]

Hi,

I'd appreciate any thoughts on how to pull a few DB out and make the car quieter. Thanks for the input.

[edwardb]

Insulate the inside 100%, double up the firewall. Fill the door sills on the outside of the chassis between the body and the aluminum panels along the sills which is just opposite of where the pipes are. I mentioned this in my build thread and tried to stuff some insulation down into there after mine was done. Maybe helped, but can't be sure. You can feel the aluminum on the inside drumming a bit from the side pipes. Good insulation would cut that down and maybe help with sound levels. Next up is what pipes you choose. Factory Five's are loud. Regular Gas-N's are about the same DB but not as harsh. What I have. I believe Gas-N's are available in the touring option for the Coupe. Supposed to be quieter. Boig pipes are quieter, but only available unfinished, also require the Boig headers (as I understand) plus are a single pipe design. For me I want the classis dual pipe look. This video describes a homemade option if you're so inclined: https://www.youtube.com/watch?v=6cDpWwb-Yfc. Finally, windows are basically a must if you're concerned with sound and then you also need A/C. I have both and all good. But some try to get away without.

Final comment: IMO it's about expectations. Taking every measure possible is going to tone it down some. But at the end of the day, it's a loud car and you can only do so much. We wear ear protection and love our Coupe. Noise is just not a factor affecting our enjoyment of it.

[Jphoenix]

I’ve used Soundown insulation to quiet the diesel engines on my boat and my bus and it works great.

https://www.amazon.com/Soundown-INSULATION-BARRIER-32-54/dp/B000N9LCWS/ref=sr_1_3?gclid=Cj0KCQiAic6eBhCoARIsANlox84_RYySs TNPn7BWcvvKS9tmdVJ91ipPcV5uB2RA3sTmsvr1hIMIXjwaApM sEALw_wcB&hvadid=234065670681&hvdev=c&hvlocphy=1027744&hvnetw=g&hvqmt=e&hvrand=8908851583203283379&hvtargid=kwd-298629719038&hydadcr=24656_9648981&keywords=soundown+insulation&qid=1674865396&sr=8-3

Not cheap, but it works, comes in different thickness, the mass dampening barrier in the middle is the secret, barium-infused vinyl if I recall correctly. I cut it with a Fein tool, the center layer is tough, jigsaw might work.

http://www.jimphoenix.com/wp-content/gallery/pt36-engine-bay/IMG_4116.JPG

[David Williamson]

I have the Boig single pipe setup on mine, quieter but still loud. One factor in how loud the car will be is the engine design, a mild cam will not be as loud.
David W

[GoDadGo]

Ear Plugs!

[Jim1855]

And GoDad replies with the obvious, correct and least expensive solution. Would've been my suggestion as well. Quiet pipes don't help reduce 70mph wind & tire noise.
Jim

[David Williamson]

Yea ear plugs help but it is still loud. In the coupe the road and wind noise is not as much of a problem as it is in the Cobra. The ear plugs help but the low frequency rumble from the engine still goes through them.
David W