Sound decibel level of FFR cars.

[Kalstar]

I went with Factory Five this weekend to the Babson College car show. Lots of beautiful cars, Alfa c8, several Lambos , McLaren 12c spyder and my favorate a Spyker 8. Anyway back to the story. The organizers had an exhaust sound off so we said why not. FFR had brought the 33, 818r, Nate's coupe and my GTM.

GTM 105 db (stock H-pipe) cats but no mufflers.
818R 105 db (enlarged turbo).
33 Hot Rod 106 db (Not sure of engine specs) rear exhaust.
Coupe 112 db (5.0 with Powerdyne supercharger) stock side pipes.

Nate's car took the loudest exhaust of the day of about 35 cars that entered.

Figured this info would be of interest.

[BubbaDuss]

It is a little bit.

Curious if kit cars are subject to similar rules of production exhaust. The neighbor to my office has put adhesive warnings on my GTO for being to loud.
Now, I work with the police department here and decided to test it anyway. I clocked in at 79 decibels. and the legal limit in Florida is 77.

F.S. 316.293(5)a

but a kit car is not bound by many of the rules production vehicles must adhere to. I'm wondering if I will have to deal with his shenanigans in the future.

[LCD Gauges]

Thanks for the numbers. How did they measure the sound, (dBA, dBC?), and from what distance?

[Kalstar]

Thanks for the numbers. How did they measure the sound, (dBA, dBC?), and from what distance?

DBA at 1 meter.

[LCD Gauges]

So that was just a big rev-fest. The numbers would be even higher under load (dyno, or accelerating)! :cool:

I put some estimates on my web site for the GTM based on other supercar values. I'd also like to get some
readings inside the cabin at idle, highway, and accelerating once all the sound dampening, and glass is installed.

[crash]

IIRC the FFR PDG GTM is about 85 db under full load, as measured by the race officials at Thundrhill with this exhaust setup...although I did add two pre mufflers that are straight through 3" design ahead of the main muffler on each bank because it was too loud with this exact setup you see here.

[LCD Gauges]

I saw your video on making that muffler (x-section). I'm betting that pictured setup would have ranked fairly high at the dB contest!

[Joe Scott]

33 Hot Rod 106 db (Not sure of engine specs) rear exhaust.
.

The Flame Hot Rod is stock coyote, with our rear exit system

[kabacj]

this exact setup you see here.

I need to experiment with something like what you describe. Ideally I could swap the kooks cats for mufflers when I run limerock park where we must be sub 85 db and run without either normally.

Nice air jacks. Do u have one or 2 in the front.

John

[VD2021]

So that was just a big rev-fest. The numbers would be even higher under load (dyno, or accelerating)! :cool:

I put some estimates on my web site for the GTM based on other supercar values. I'd also like to get some
readings inside the cabin at idle, highway, and accelerating once all the sound dampening, and glass is installed.

I'm shooting for a goal of sub 65dB in the cabin at idle and sub 75dB under accelleration.

[crash]

I need to experiment with something like what you describe. Ideally I could swap the kooks cats for mufflers when I run limerock park where we must be sub 85 db and run without either normally.

Nice air jacks. Do u have one or 2 in the front.

John

We have two in the front. I don't want to disparage any company but there is an expensive way and a cheap(OK cheaper) way to buy the pre mufflers. Just be prepared, the good quality Stainless mufflers I used that are repackable ran about $300 A PIECE. Let me know if you are interested and I will PM you the info on them.

BTW- We ran at Laguna Seca with this setup and had no issues at all, which is amazing because EVERY other car I had ever taken to Laguna had sound issues.

[LCD Gauges]

I'm shooting for a goal of sub 65dB in the cabin at idle and sub 75dB under accelleration.

Out of Interest...

I read a while ago that Mercedes (I think) used out of phase acoustics played through the stereo to cancel exhaust
noise in the cabin. Something about mics/sensors in the exhaust, and then invert the signal in the cabin.

Not too sure on the technology there, it would take one hell of R&D program to position the speakers to cancel the
ambient sound waves.

My buddy has a dB meter so I'll be sure to measure the stats on my car. Please post yours as well; I have a feeling
you'll meet your goal!

[VD2021]

Out of Interest...

I read a while ago that Mercedes (I think) used out of phase acoustics played through the stereo to cancel exhaust
noise in the cabin. Something about mics/sensors in the exhaust, and then invert the signal in the cabin.

Not too sure on the technology there, it would take one hell of R&D program to position the speakers to cancel the
ambient sound waves.

My buddy has a dB meter so I'll be sure to measure the stats on my car. Please post yours as well; I have a feeling
you'll meet your goal!

Yeah. It's the same tech Bose uses in their noise cancelling aviation headsets and headphones.

I purchased a hand help dB meter for reference. My plan starts with the primary noise culprit (the exhaust) in my overall plan to help lower the noise floor in the cockpit.