Sound deadening in the Coupe

[nick729]

Hello,

need some advice on sound deadening on my Coupe. I ordered the sound deadening kit from FFR, but i was surprised by the fact that it comes in 2 different types; the anti-vibration material ~2.2mm thickness self adhesive butyl compound with aluminum foil and the other is just foam.

Since the sound deadening is not complete in my case, some bits are missing and some seem to be random scraps (by the way most of the numberings on the foam pieces were random and did not correspond to the fitting guide), i am planning on ordering some more of the butyl compound stuff. The question is should i ditch the foam material all together and go with all butyl compound? Are there any drawbacks to it? Also, should i order 2mm, or go with 4mm (not sure how much of a difference the extra thickness will make)? Since i will be running stock exhaust with LS427, my thinking is that the only purpose butyl deadening will serve is to stop the panels from vibrating as there is no point in sound insulation when you have straight pipes at your ear, hence, there is no point in going thicker..?

The foam is meant to be used on the sides and top of the trans tunnel. Are there any obvious reasons not to use butyl compound instead of foam there? I plan on covering the top of the trans tunnel with leather.

Thanks!

Picture of the foam pieces
viber_image_2024-05-28_08-34-02-451.jpg

[edwardb]

I didn't buy the sound deadening kit from Factory Five for my Coupe build. But did something similar. I used Second Skin Damplifier Pro Butyl Rubber 2mm Sound Deadener (which also has a thin aluminum skin on one side) and Dynamat 11101 Dynaliner 1/8" Thick Self-Adhesive Insulation. I have both layers on the footboxes and firewall. I sprayed Lizard Skin everywhere else. But a single layer of Damplifier Pro would have been similar. Just my personal choice. Then all covered with carpet. Heat isn't an issue. Sound is controlled about as much as can be expected with the Coupe. Based on your description, I think what you have is OK. I'd use it.

You didn't mention it, but I did in my build thread and have offered the same advice several times. My opinion is that a significant amount of sound is from the side pipes tucked into the body and just inches from both seats. I highly recommend you thoroughly insulate the area between the chassis sides and the body below the doors. There's room in there to add significant insulation and easy to do before the body is installed. I tried to stuff some in there after mine was complete and I think it may have helped some. But during the build is the time to do it. You also may want to consider the inside roof area. I sprayed Lizard Skin and then UPOL Raptor as the finish layer. I didn't use the kit supplied headliner. Don't know how much it helped. But can't hurt. I have Gas-N side pipes where are quieter than the original steel side pipes that came with my kit but probably similar to the SS ones FF is supplying now.

At the end of the day, our Coupe is still loud and we use ear protection. I really don't know if there's any way to get around that. When we're riding in the Coupe, not unusual for my iPhone to start warning "Loud Environment." Thanks. I think we knew that.

[nick729]

I didn't buy the sound deadening kit from Factory Five for my Coupe build. But did something similar. I used Second Skin Damplifier Pro Butyl Rubber 2mm Sound Deadener (which also has a thin aluminum skin on one side) and Dynamat 11101 Dynaliner 1/8" Thick Self-Adhesive Insulation. I have both layers on the footboxes and firewall. I sprayed Lizard Skin everywhere else. But a single layer of Damplifier Pro would have been similar. Just my personal choice. Then all covered with carpet. Heat isn't an issue. Sound is controlled about as much as can be expected with the Coupe. Based on your description, I think what you have is OK. I'd use it.

You didn't mention it, but I did in my build thread and have offered the same advice several times. My opinion is that a significant amount of sound is from the side pipes tucked into the body and just inches from both seats. I highly recommend you thoroughly insulate the area between the chassis sides and the body below the doors. There's room in there to add significant insulation and easy to do before the body is installed. I tried to stuff some in there after mine was complete and I think it may have helped some. But during the build is the time to do it. You also may want to consider the inside roof area. I sprayed Lizard Skin and then UPOL Raptor as the finish layer. I didn't use the kit supplied headliner. Don't know how much it helped. But can't hurt. I have Gas-N side pipes where are quieter than the original steel side pipes that came with my kit but probably similar to the SS ones FF is supplying now.

At the end of the day, our Coupe is still loud and we use ear protection. I really don't know if there's any way to get around that. When we're riding in the Coupe, not unusual for my iPhone to start warning "Loud Environment." Thanks. I think we knew that.

Thanks for the reply!

So your recommendation as i understand is to use Butyl Compound 2mm everywhere and no foam, and there is no point in going thicker? I would plan on using it on all interior panels; footboxes, floor, below the doors, trans tunnel (sides and top), behind seats, hatch sides and floor.

I was planning on using 5cm sound deadening foam something like this (https://www.seamusician.com/image/se...-1250x1250.png) in the space you mentioned, but was told it is a bad idea as it will soak up moisture and therefore lead to all sorts of problems. Thinking about it, i don't plan on driving in the wet. After your comment i'm thinking maybe i should rethink this decission..? Do you have anything in mind you could recommend, or would the foam in my link be ok in your opinion?

I have the inside of the hood and body including the roof coated in Upol Raptor and i don't intend to use the provided headliner as i don't like the feel and look of the headliner, might need to rethink that once again

[Namrups]

I followed Paul's lead with the butyl layer covered with the foam layer then carpet in the footbox area. Also used Lizard skin sound and heat material on the rest of the interior panels covered by carpet. I also added 1" seat cushion foam in the exterior framing next to the seats. (pic attached) I did not use any thing on the tunnel cover as I covered that with padding and vinyl. I had some of the footbox foam left over so I added it to the door panel skin. I did use the FF supplied headliner. I also have the side windows installed. With all of this, these cars are loud. If I had to rate the change I would say it may have gone from a 10 being the loudest to maybe a 7 now. When using my phone for directions I can hear her talking but cannot make out what she is saying. My solution was to buy a pair of Apply Air Pod Pro's. They are noise cancelling. They connect to my non-apple phone using bluetooth. I was amazed how well they work. I can hear my phone without any issues now and the sound level of the car using them is a 3.

[David Williamson]

I used Dynamat everywhere on mine including under the head liner. I also put a thin foam pad under the fake leather cover on the top of the transmission cover to give it a little padding. I have Boig quiet pipes and it is still loud, no idea how much the Dynamat helps but it must do something.
David W

[Kbl7td]

Another couple areas no one talks about is the area just behind your seat in front of the rear wheels. My plan is to put another panel of aluminum skinning there as well. With closed cell foam sandwiched between with the butyl rubber.

Additionally inside the doors. I plan to again use the butyl kilmat inside the doors. Then attempt to pour in some expanding foam in the doors while they are laying with the outside skin flat. Hopefully can get an inch or some of foam which should help with noise and a firm door close.

As others have said, putting in the headliner will absolutely help. There’s a reason rooms with good acoustics have foam to help dampen sound from bouncing around. That hard top without headliner isn’t going to help.

[edwardb]

Thanks for the reply!

So your recommendation as i understand is to use Butyl Compound 2mm everywhere and no foam, and there is no point in going thicker? I would plan on using it on all interior panels; footboxes, floor, below the doors, trans tunnel (sides and top), behind seats, hatch sides and floor.

I was planning on using 5cm sound deadening foam something like this (https://www.seamusician.com/image/se...-1250x1250.png) in the space you mentioned, but was told it is a bad idea as it will soak up moisture and therefore lead to all sorts of problems. Thinking about it, i don't plan on driving in the wet. After your comment i'm thinking maybe i should rethink this decission..? Do you have anything in mind you could recommend, or would the foam in my link be ok in your opinion?

I have the inside of the hood and body including the roof coated in Upol Raptor and i don't intend to use the provided headliner as i don't like the feel and look of the headliner, might need to rethink that once again

The aluminum lined butyl (lots of brands) is mainly for sound. The foam (also lots of brands) is mainly for heat. In my reply I tried to say I used both layers in the footboxes and firewall and also what I'd recommend. Same as I understand you received from Factory Five. For the rest I used Lizard Skin. Mainly there the concern is sound. A stick-on sound product would also be fine. I wouldn't recommend the foam you suggested. I'd stick with materials intended for automotive use. Plus while thicker materials might give slightly better results it's at the expense of taking up already limited space. I don't drive my Coupe intentionally in the rain. Not at all (obviously) during our Michigan winters. With a closed top and windows, moisture isn't something I'm concerned about nor do I think it's an issue with the materials I described.

Good to see you're getting some other responses. This issue is talked about a lot with Coupe builds. Most messages are similar. The heat/sound issues can be mitigated somewhat. But it's going to be loud no matter what. Good luck.

[David Williamson]

The noise in the Coupe is almost 100% from the engine not road or wind like in the open top Cobra. In my coupe with a Dart 363 engine it is a low frequency sound and on the highway you hear each exhaust pulse from the side pipes.
David W

[nick729]

The aluminum lined butyl (lots of brands) is mainly for sound. The foam (also lots of brands) is mainly for heat. In my reply I tried to say I used both layers in the footboxes and firewall and also what I'd recommend. Same as I understand you received from Factory Five. For the rest I used Lizard Skin. Mainly there the concern is sound. A stick-on sound product would also be fine. I wouldn't recommend the foam you suggested. I'd stick with materials intended for automotive use. Plus while thicker materials might give slightly better results it's at the expense of taking up already limited space. I don't drive my Coupe intentionally in the rain. Not at all (obviously) during our Michigan winters. With a closed top and windows, moisture isn't something I'm concerned about nor do I think it's an issue with the materials I described.

Good to see you're getting some other responses. This issue is talked about a lot with Coupe builds. Most messages are similar. The heat/sound issues can be mitigated somewhat. But it's going to be loud no matter what. Good luck.

Just to clarify, the FFR sound Deadening kit is a single layer insulation, in some areas you are meant to use only the Butyl Compound (footboxes, floors, behind the seats and hatch area including sides) in other areas just the foam (trans tunnel sides and top below the doors on the inside and i believe the corner uprights behind the seats and some other miscellaneous small pieces).

After searching i came up with this for the empty spaces below the doors: https://comfortmats.eu/product/sound_trap/ Seems like this should work, it's intended use is for the inside of regular car pillars and is somewhat waterproof.

Thanks for the many replies guys, maybe i need to rethink my plan

[lewma]

I put dynamat all over the place and put sound deadening below the doors where the side pipes are. We took a couple of runs in the car late last week for Brake & Lights inspection, then California Highway Patrol inspection ( both passed ) but this thing is loud. Not entirely sure anything is going to greatly reduce the sound inside the car. It is what it is and ear protection is likely needed.

[nick729]

Does anyone by chance know if the body sits flush to the frame under the door sills or is there a gap there (how big?)? I have stored my body shell and thus can't check myself.

The foam i am planning on using under the doors is 95mm thick (~3.75") and the space under the doors is around 45mm (~1.75"). Wondering if i can save myself the bother of cutting it up.

This is the foam i plan on using: https://comfortmats.eu/product/sound_trap/

Thanks!

[David Williamson]

The body tucks under the lower frame rail under the doors. It is not water tight so any insulation you put in there should be closed cell foam or it will be full of water. I have 2 layers of Dynamat in the area.
David W

[Namrups]

IMO you can use sound deadening material all over the body areas including inside the doors. I have. But there is no way to deaden the sound through the windows. Any type of sound deading material helps but don't think you are going to reduce it to the point where you don't need ear protection. Again, my opinion. (Isn't the noise one of the reasons we build these cars? It was for me.)

[lewma]

Does anyone by chance know if the body sits flush to the frame under the door sills or is there a gap there (how big?)? I have stored my body shell and thus can't check myself.

The foam i am planning on using under the doors is 95mm thick (~3.75") and the space under the doors is around 45mm (~1.75"). Wondering if i can save myself the bother of cutting it up.

This is the foam i plan on using: https://comfortmats.eu/product/sound_trap/

Thanks!

Yes, the body door sill sits on the frame.

Good luck with sound deadening

[Alan_C]

Any one has both that can compare the sound level between a roadster and the coupe? Would the roadster appear to be quieter with the open cockpit and higher wind noise?
In addition to the sound deadening suggestions here, any other changes folks have found effective?
I already plan to buy aftermarket side pipes like those from Gas-N. On my MK4, I used the CAT/J-pipes with integral CATs. The CATs had two positive effects, one they did reduce the sound level and two they also reduced the amount of heat that reached the side pipes. The CATs appeared to act like heat sinks and hold heat that would otherwise reach the side pipes. I used Gas-N side pipes as well and you could have a conversation at speeds up to 70 MPH.
I am thinking of designing custom 4 into 4 headers with small CATs or mufflers to take some of the edge off the sound level. I too want to hear the exhaust sound, just not drown in it.

[nick729]

The body tucks under the lower frame rail under the doors. It is not water tight so any insulation you put in there should be closed cell foam or it will be full of water. I have 2 layers of Dynamat in the area.
David W

Thanks for the heads up. This foam is water resistant, not sure if that will help, also i only intend to drive the car in dry conditions - i've already ordered the foam so I guess I will decide what to do with it once i receive it.

What would be the main issue if the foam does somehow accumulate moisture? Mold?

I am well aware of the noise this car makes, i am more worried about vibrations rather than noise

[Namrups]

Thanks for the heads up. This foam is water resistant, not sure if that will help, also i only intend to drive the car in dry conditions - i've already ordered the foam so I guess I will decide what to do with it once i receive it.

What would be the main issue if the foam does somehow accumulate moisture? Mold?

I am well aware of the noise this car makes, i am more worried about vibrations rather than noise

I ran my coupe last summer in an unfinished state. I had not installed the Lizard skin (both sound and heat) nor any of the carpet. I had applied all of the panels sealing themwith silicone. There were a lot of vibrations and rattles. This past winter I "finished" the build with the Lizaed skin, carpet, sound mats inside of the doors and rubber around the doors and rear window. The rattles and vibrations were gone. The car sounds and feels much more solid now. Actually, at car shows, people are amazed at how solid the door sounds when closing it.

Scott

[burchfieldb]

Any who has both that can compare the sound level between a roadster and the coupe? Would the roadster appear to be quieter with the open cockpit and higher wind noise?
In addition to the sound deadening suggestions here, any other changes folks have found effective?
I already plan to buy aftermarket side pipes like those from Gas-N. On my MK4, I used the CAT/J-pipes with integral CATs. The CATs had two positive effects, one they did reduce the sound level and two they also reduced the amount of heat that reached the side pipes. The CATs appeared to act like heat sinks and hold heat that would otherwise reach the side pipes. I used Gas-N side pipes as well and you could have a conversation at speeds up to 70 MPH.
I am thinking of designing custom 4 into 4 headers with small CATs or mufflers to take some of the edge off the sound level. I too want to hear the exhaust sound, just not drown in it.

I plan on doing the same. I 3D printed a kit similar to the Icengine Works kit for a fraction of the cost, that I will use to lay it out. I have to build custom headers anyways, since I decided to make things difficult and run a Cleveland. Have tou looked into what CATs you might use?

[Alan_C]

I plan on doing the same. I 3D printed a kit similar to the Icengine Works kit for a fraction of the cost, that I will use to lay it out. I have to build custom headers anyways, since I decided to make things difficult and run a Cleveland. Have tou looked into what CATs you might use?

No research on CATs as yet. I believe Magnaflow makes HP CATs. A quick search online found these, but I did not look at dimensions.
https://www.amazon.com/MagnaFlow-539...A14H0YDY9OH3OC
I too will need custom headers as I plan to use a Gen V LT1 from a Camaro SS for the engine and 10-speed auto transmission. No support from FF or Gas-N for the LT1 as yet.
As you progress in your header design, if you are willing to sell a copy of the fabrication kit, I would be interested.
Right now my focus is on moving along on my garage expansion. So much lost time between the available schedules of the sub-contractors. Fortunately FF was willing to move me to the back of the coupe production giving me plenty of breathing room to finish construction. I will very likely not do too much on the coupe till next year as I still have to finish body, paint, and reassembly on my Mustang restomod. Having the coupe kit in house will be motivation to get the Mustang done to make room on the lift for the coupe chassis. My wife wants me to stay busy in retirement, so between her projects for me and my own, that is not a problem for years to come.

[burchfieldb]

No research on CATs as yet. I believe Magnaflow makes HP CATs. A quick search online found these, but I did not look at dimensions.
https://www.amazon.com/MagnaFlow-539...A14H0YDY9OH3OC
I too will need custom headers as I plan to use a Gen V LT1 from a Camaro SS for the engine and 10-speed auto transmission. No support from FF or Gas-N for the LT1 as yet.
As you progress in your header design, if you are willing to sell a copy of the fabrication kit, I would be interested.
Right now my focus is on moving along on my garage expansion. So much lost time between the available schedules of the sub-contractors. Fortunately FF was willing to move me to the back of the coupe production giving me plenty of breathing room to finish construction. I will very likely not do too much on the coupe till next year as I still have to finish body, paint, and reassembly on my Mustang restomod. Having the coupe kit in house will be motivation to get the Mustang done to make room on the lift for the coupe chassis. My wife wants me to stay busy in retirement, so between her projects for me and my own, that is not a problem for years to come.

I talked to Georgie about mine and he would make custom ones, but it was kind of pricey, and no CATs. He may do the CATs, but that was not a consideration of mine at the time. I will let you know how the 3D printed parts work before I commit to sellling. I did find these CATs, which seemed to get really good reviews, and they have lots of options depending on your needs.

https://www.gsportbygesi.com/g-sport...stems-products

[Alan_C]

I talked to Georgie about mine and he would make custom ones, but it was kind of pricey, and no CATs. He may do the CATs, but that was not a consideration of mine at the time. I will let you know how the 3D printed parts work before I commit to sellling. I did find these CATs, which seemed to get really good reviews, and they have lots of options depending on your needs.

https://www.gsportbygesi.com/g-sport...stems-products

Those CATs look good, but good golly I about choaked on the prices! It is good that I have time as my use of that is free.

[Alan_C]

I saw this CAT from Kooks, unfortunately similar pricing. Any idea as to how much length there is between where the pipes from the flange merge to a group and the flange for the side pipe attachment. Most of the CATs are 8 inches in length, the Kooks unit below is 7 inches. Seems like there would be enough room to work with?

https://www.summitracing.com/parts/k...90140#overview

[burchfieldb]

I saw this CAT from Kooks, unfortunately similar pricing. Any idea as to how much length there is between where the pipes from the flange merge to a group and the flange for the side pipe attachment. Most of the CATs are 8 inches in length, the Kooks unit below is 7 inches. Seems like there would be enough room to work with?


https://www.summitracing.com/parts/k...90140#overview

I was looking at the OBD2's, which are about $200 each. The space to work in is tight, so the location is going to depend on how crazy you get with the routing and how far your O2 sensor needs to be from the merge collector.

[Alan_C]

Copy that on the OBD2s. 3 inches for inlet and outlet, inexpensive and short at 7 inches in length. Not that it really matters, but at 4 inches in diameter, you could hide them pretty effectively with header wrap.

https://n75motorsports.ca/products/u...ytic-converter

[nick729]

After taking into consideration all the suggestions, i have decided to use this foam for the inside of the door sills: https://comfortmats.eu/product/sound_trap/

90mm thickness foam, which is used for A/B/C pillars in regular cars, it is water resistant and very soft and pleasant feeling. I cut it oversized so that it is compacted in the open spaces and will be squished down to about half it's original thickness with the body on. Cutting it is not that hard, just used two planks of wood to squish it down along the cut mark and cut it with a sharp utility knife.

viber_image_2024-07-10_10-57-05-734.jpg

[JimStone]

After taking into consideration all the suggestions, i have decided to use this foam for the inside of the door sills: https://comfortmats.eu/product/sound_trap/

90mm thickness foam, which is used for A/B/C pillars in regular cars, it is water resistant and very soft and pleasant feeling. I cut it oversized so that it is compacted in the open spaces and will be squished down to about half it's original thickness with the body on. Cutting it is not that hard, just used two planks of wood to squish it down along the cut mark and cut it with a sharp utility knife.

viber_image_2024-07-10_10-57-05-734.jpg

Where did you buy it from? I don't see any American resellers

[Dave Tabor]

For what it's worth I added ~100 lbs of Kilmat/butyl/foil and 1 cm thick heavy mass vinyl throughout the car (and filled the dead space under the door sills).

I still had to wear earplugs to so I ripped most of it out (harder than putting it in). All that stuff did was make the car slower. I did leave a piece of Kilmat in each door and couple of pieces on the roof interior.

Wrapping Kilmat around your head may work pretty well and cut down on the weight of the car.

https://www.amazon.com/Kilmat-Deaden...ct_top?ie=UTF8

Dave
Gen III #17
21,500+ miles.

[nick729]

@JimStone - I'm from Lithuania, so i just bought from a local dealer, as far as I can tell it is only available in Europe. You could order from a dealer in Europe, or alternatively find something similar in US. The foam is designed to go inside the A/B/C pillars in cars, so i'm sure something similar should be available in US.

@Dave Tabor - I am well aware of how loud the car is, it's just my personal choice to get rid of any possible vibrations and maybe marginally make the car quieter at the same time. With 630bhp, doubt i will be worried about making the car lighter and faster

[UpNorth]

I must say I’m a little puzzled at reading you guys.
This car is LOUD. Period.
I maybe wrong but I feel whatever you do on insulation you’ll still need to wear some kind of earring protection…
Working on muffling the sound at the exit of the engine is the only possible solution…And even then…
Flame suit on…

Cheers!

Francois Giroux

[lewma]

This car is LOUD. Period.

I agree