Additional layers of insulation

[skullandbones]

Hi all,

I'm building a roadster but thought the thread would be more interesting on the 818 side since I followed a thread that discussed the various way of reducing sound resonance. I think these projects actually create a problem by using flat aluminum panels (which was focused on in that above mentioned discussion). So using the aluminum creates a great light and strong subframe but the "tin can" syndrome also comes along with the positive aspects. I am using some additional layers of insulation (cheap in this case as I already had them from remodeling). One layer is a thin green rubber material used under laminate floors to dampen sound. The other layer is a traditional carpet pad (premium quality). Actually, it looks the same as when it was installed.

Dynamat is producing a product called DynaPad which uses the same strategy based on "Dissimilar Layer Insulating" technology. So the physics has been done and the concept is being used in many applications besides automotive. When I was insulating my cockpit behind the seats, I realized that the 818 firewall will look very similar to this same portion of my project. So I thought I would include some pics to show and see what people think about the idea. It seems many in the roadster camps have pretty much established their line of action based on their experiences with their builds but I haven't seen them talking a lot about using extra layers of dissimilar pads in the process. BTW, it's extra labor and a little extra weight. Also, there are critical areas where the clearance can be tight but for the most part, the extra space taken is wasted space anyway. I am also using a Dynamat like product which is great but I am thinking it will be the primary heat shield whereas the other layers are more for sound absorption.

The advantage of the 818 like the GTM is that the primary source of unwanted sound is coming from one direction because of the design. Unfortunately the roadster's cockpit is surrounded by those "noise makers".

Have a look. Thanks, WEK.:cool:

[NonProfit]

Looks great WEK!

I was considering some form of rubberized undercoating on the underside. Have you any insight as to if that's a good idea?

[narkosys]

some of the peeps in the GTM forums are spraying their aluminium panels with truck bed coatings. it apparently deadens the sound as well as provide the usual rock protection.

i am surprised that they don't put in beads in the panels as they help make the panels stronger.

P

[Xusia]

I definitely planned to use similar techniques to make it quieter (mine will be a daily driver, so I want some degree of "luxury!" LOL). Things may change once I'm into the project, but my plan at this point was to use something like Dynamat to line the inside of the cockpit in as many areas as practical, and the spray the underside of the body with truck bed liner (Oregon gets a lot of rain, so this is protection against rust and deterioration as well as sound proofing). I know it will add some weight. It's a trade off I'm happy to make.

EDIT: I will be looking to apply some spray foam where it makes sense to dampen vibrations and therefore reduce sound transfer. Mostly I'm looking to block road noise and engine noise. YES I want to hear the engine, but only when I want. I don't want to be forced to hear it all the time.

[VD2021]

I understand what you're going for with the different layers of material. You are definitely on the right track and what you have done will make a reduction in the noise floor.

I have experience in this area and would like to add some information that may be helpful.

When it comes to reducing the noise floor and quieting the cabin my experience is to duplicate (with in the limitations of the vehicle) what has been very effective in production autos. This with an emphasis on the higher end and luxury vehicles. This is normally accomplished in three parts or layers. 1) Dampen the panel. 2) Block the noise. 3) Absorb noise and decouple the panel from the sound blocker.

This is accomplished in different ways for different parts of a vehicle. The floor will normally have formed panels with a dampener applied. This is normally followed by the vehicles carpet which contains a sound absorber/decoupler (the carpet's insulation) and a sound blocker (the heavy mass loaded portion above the insulation). Fire walls may follow the dampener with an even thicker insulation to compensate the the engine noise and heat. The roof may or may not have a dampener or a sound absorber/decoupler. If not the headliner panel and the liner material are it.

So our kits where designed to be light and fast and with this comes a loud noise floor. Our Exhaust and engines are inches away from our ears and the roadster is open to the environment. This makes if extremely difficult if not impossible, in some cases, to get the noise floor down. The three part approach can still be very effective.

1) Dampen the panels. For our kits, adding bends and/or rolls is not practice for most of us, but adding the dampener (mat or liquid) will do an excellent job dampening the aluminum panels. Which is best, mat or liquid? The answer is both. IMO a combination will make for an easier install, but is purely preference. There may be a area where you are unable to properly install mat that you can shoot with the liquid or the reverse. With the panel dampened it will have a greatly reduced tendency to resonate and transfer sound through the panel.

2) Add a sound absorbing/decoupling layer. Automotive carpet insulation is a great sound absorber and decoupler (I would expect the home carpet insulation would work, but It doesn't have the same make-up as the automotive type). Foam (closed cell) is another option. This layer decouples or physically separates the panel from the sound block and also absorbs some of the sound that passes through the panel. The separation of the panel and sound blocker is required. If the sound blocker is placed directly next to the panel it will transfer the sound that is passing through the panel instead of blocking it.

3) Add a sound blocker. This can be accomplished in different ways and with different items. A mass loaded vinyl over the insulation/foam, a door panel with a layer of mat applied to the back of it. Dyna Pad which is a combo product of 2 and 3. You can also have great results with only 1 and 2 of the list.

[VD2021]

I definitely planned to use similar techniques to make it quieter (mine will be a daily driver, so I want some degree of "luxury!" LOL). Things may change once I'm into the project, but my plan at this point was to use something like Dynamat to line the inside of the cockpit in as many areas as practical, and the spray the underside of the body with truck bed liner (Oregon gets a lot of rain, so this is protection against rust and deterioration as well as sound proofing). I know it will add some weight. It's a trade off I'm happy to make.

When considering this for a DD its really not a huge weight addition. Mat and liquid dampeners are .3-.5lbs per sqft, depending on the thickness. A closed cell foam or automotive insulation may add 3 to 5 lbs to the vehicle. If you were to install 25sqft of dampener and foam, in the 818, you're looking at an addition in weight of ~8-10lbs.

A mass layer sound blocker will come in at about the same weight as the dampener so you would effectively double the weight addition.

[Silvertop]

This is going to be a very useful thread for a lot of us, I think. Keep the tips coming, guys..........!

[HelluvaEngineer]

For my corvette I used Dynamat on the floors, firewalls, doors and anywhere else I could glue the stuff that made sense. It was amazing what a difference it made. Plus my feet did not get hot when I was driving it hard. I was going to do the same thing on the 818. But I was also thinking about putting some foam into the tube frame pieces? Not sure if that would be overkill or not. I have never had a full tube frame car before, just restored/modded a number of older cars (and my Legacy GT)

[VD2021]

H,
Thanks for posting your results as it brings up a point that I feel should be brought out.

Most if not all production autos will greatly benefit from the addition of only mat (a dampener). Why?...... Well the three part system is already in place and the mat addition is increasing the systems effectiveness. The autos current dampener being too thin, drying out or just being inferior set the stage for very good results.

We don't have this benefit with our kits because the system is not there, at the start, to be improved upon. For the best results (Or to achieve what we're use to in our production auto) We have to build the system from scratch all while working within the limitations of the kit (two of which are flat panels and limited space).

[MiniVanMan]

When it comes to reducing the noise floor and quieting the cabin my experience is to duplicate (with in the limitations of the vehicle) what has been very effective in production autos. This with an emphasis on the higher end and luxury vehicles. This is normally accomplished in three parts or layers. 1) Dampen the panel. 2) Block the noise. 3) Absorb noise and decouple the panel from the sound blocker.


This is the key point right here. Know what tool you're using and for what job. There is no one tool that does it all. Dynamat mats are dampeners and do little to nothing to block noise. Unless you add layer upon layer, creating a mass loaded blob of butrate goo. Sound blockers are best decoupled.

Mass loaded vinyl (MLV) is an excellent sound blocker. You can source it from several places. Not hard to find. It does add weight. You want to use it in combination with a decoupler. Pick your poison there. Carpet padding, etc. The application of MLV should be thorough with no gaps between the seams. MOST effective on the firewall and floor board.

For resonance/vibration, you want to use a dampener (Dynamat being the most commonly known). Dampeners in this form are usually a butyl (sometimes cheaper asphalt is used) base with an aluminum flashing. MORE IS NOT BETTER HERE. MORE is just heavier. Go for 25% coverage. Placement is more critical than actual quantity. 25% of the panel, covered in the center will do the trick. Flat panels are more prone to vibrations than curved panels. Dampening a corner, or bend is pointless as these won't resonate much to begin with. So, again, 25% coverage on all flat or mild to moderately curved panels will provide plenty of damping without adding massive amounts of weight to the car.

Read through this guy's site. (He's also a friend). http://www.sounddeadenershowdown.com/cgi-bin/index.cgi

All the information you need is on that site. He also offers excellent products for very good prices, but that's just a shameless plug for a friend. My only real recommendation is stay away from vendors that claim 100% coverage of dampening material. SDS is the first company to come along and push the 25% idea. It doesn't sell as much product so it's not as profitable. He introduced the "tile" (CLD tiles) to the industry, and many are now copying. He used to do independent testing for the various vendors like Dynamat, Secondskin, etc, etc, etc then started his own company.

[skullandbones]

H,
Thanks for posting your results as it brings up a point that I feel should be brought out.

Most if not all production autos will greatly benefit from the addition of only mat (a dampener). Why?...... Well the three part system is already in place and the mat addition is increasing the systems effectiveness. The autos current dampener being too thin, drying out or just being inferior set the stage for very good results.

We don't have this benefit with our kits because the system is not there, at the start, to be improved upon. For the best results (Or to achieve what we're use to in our production auto) We have to build the system from scratch all while working within the limitations of the kit (two of which are flat panels and limited space).

Good points! There have been several sentinel moments over the course of this build. Although FFR furnishes you with a fundimentally sound projuct (no pun), the project is a blank canvas so to speak. So when I have these Aha moments, I realize how much you can affect the outcome of the project by your mods and approaches to how you solve various issues. It keeps me grounded to the point I don't begrudge the extra work which will not be seen most of the time in the finished product. So I'm hoping the sound environment will be affected by this process so that I can enjoy the experience a little more. There is a fine line between a sound that is annoying and when it fades into the background as white noise. I am looking forward to hear the suction of the cool air tube, the sound of the engine ramping up with alum flywheel, and maybe reducing the multiple extraneous and unwant noises. It may even make the sound of the side pipes more defined. BTW. I'm stealing a trick from AZPete by adding isulation on both sides of the x members at the bottom of the doors right next to the side pipes. Also, I plan on doing something to dampen the doors but haven't gotten to that detail yet. I think it will involve cutting into the door shell to attain access to the interior. Has any one ideas on that part as well? The 818 doors are larger than the roadster ones so they will probably be a source of resonance, etc. I think I am going to reserve the decision to add Lizard Skin or something similar to the outside of some panels depending on how my evaluation goes with this project as I drive it. Thanks, WEK.

[blueoval_bowtie_guy]

The first thing I thought of when I saw the 2nd layer was how you were going to get it dry when it gets wet. Then I saw where you live, so that isn't much of an issue. Here in the Northeast, we REALLY have to make sure that anything we use in a car that even stands a chance of getting wet is to make sure that we don't use anything that will absorb water (even moisture).

I used dynomat under my carpeting when I built the roadster. The first summer it was on the road the interior was bare aluminum. My wife and I both needed earplugs to ride in it. Once I put in the dynomat and carpet, we haven't needed the earplugs since.

[JAubin]

I added Raam Mat (similar to Dynamat) to my subaru when I did a custom audio setup in it. Covered that with 1/4" closed cell foam glued to the aluminum backing with 3M spray adhesive. Worked pretty well but wasn't crazy expensive. Just another source of materials... http://www.raamaudio.com/

[skullandbones]

It's true. We look at rain and humidity in an entirely different light. Months without rain and humidity at 15% makes you worry about retaining moisture in things including yourself. We celebrate the rain when it goes come. I will probably carry a light water resistent car cover (maybe nylon) to avoid the possible sudden downpour. But it's not a real issue around here. I have heard of guys drilling holes in the floor panels to avoid a "bathtub" effect when they get caught out (where it does rain). I suppose in a humid environment the possibility of mildew and mold (smell, etc) would be a not so attractive side effect if you aren't careful. I also see a rag top of some kind in my future. Thanks for your input. Just goes to show you how many tradeoffs there are in this game. WEK.

[Xusia]

LOL! Some people seriously over think things! You shouldn't have to drill a hole in a convertible to combat the effects of rain. Running the heater and fan both at max with the windows down, then leaving in a garage with the top down if possible, or at least the windows down overnight usually does the trick. In fact, it's always good practice to leave the windows down when parked in the garage to allow excess moisture to escape.

[carlewms]

Minivanman,

I just received my roadster kit and the ideas for sound control. Thanks for the link as well; good explanation of what is happening in the car sound wise. My questions are:

1. Where does heat insulation fit in to the layering? Is it a separate material or will the MLV serve the purpose?
2. How does a product like LizardSkin compare?

I am trying to keep the engine compartment side of the aluminum bare (perhaps protected with Sharkhide) and do the noise and heat control from the interior of the cockpit. I would use LizardSkin or similar spray on product in the wheel wells and underside of the car.

Thanks-Carl

[MiniVanMan]

Minivanman,

I just received my roadster kit and the ideas for sound control. Thanks for the link as well; good explanation of what is happening in the car sound wise. My questions are:

1. Where does heat insulation fit in to the layering? Is it a separate material or will the MLV serve the purpose?
2. How does a product like LizardSkin compare?

I am trying to keep the engine compartment side of the aluminum bare (perhaps protected with Sharkhide) and do the noise and heat control from the interior of the cockpit. I would use LizardSkin or similar spray on product in the wheel wells and underside of the car.

Thanks-Carl

I'm a sound guy. I know very little about heat barriers. In my estimation, I wouldn't rely on a vinyl product like MLV to handle heat duties. It may block heat, but it's still vinyl. I'd find something more suitable for that particular need. Lizard skin looks good, but somebody else will have to chime in on that. Sounds like a pretty good option though, if heat and sound solutions are your goal. Lizardskin sound dampener with Lizardskin Ceramic Coating looks good to me. The Lizardskin sound dampener is exactly that, a damper, just like the butyl and foil based sheets. How well it holds up to heat if you put it on the engine side, and then coat it with the ceramic coating, I don't know.

What I'd do, given that Lizardskin is what it says it is, Lizardskin sound damper, topped with Lizardskin Ceramic coating. I'd put the ceramic coating on both sides, and the sound damper on the cockpit side. Then find a closed cell foam suitable as a heat barrier. That foam would work triple duty as a heat barrier, sound absorber and a decoupler for the MLV. Then put your MLV over that. That would all go on the cockpit side as well.

For your floors, and all the flat sheet metal panels, I'd still go with a butyl sheet like the CLD tiles or brand of preference. For the firewall, a liquid like Lizardskin is a good option.

These are just suggestions. Somebody may come along and say I'm bat crap insane, and offer a better heat control solution. Like I said, I'm not an expert in that area.

[narkosys]

ok...you're bat crap insane :P (but what you said makes a lot of sense and are really good ideas)

P

[carlewms]

Thanks for the great ideas! I am building a non racer so weight really is not an issue but building a car that is relatively comfortable to drive is important.

[VD2021]

I'm a sound guy. I know very little about heat barriers. In my estimation, I wouldn't rely on a vinyl product like MLV to handle heat duties. It may block heat, but it's still vinyl. I'd find something more suitable for that particular need. Lizard skin looks good, but somebody else will have to chime in on that. Sounds like a pretty good option though, if heat and sound solutions are your goal. Lizardskin sound dampener with Lizardskin Ceramic Coating looks good to me. The Lizardskin sound dampener is exactly that, a damper, just like the butyl and foil based sheets. How well it holds up to heat if you put it on the engine side, and then coat it with the ceramic coating, I don't know.

What I'd do, given that Lizardskin is what it says it is, Lizardskin sound damper, topped with Lizardskin Ceramic coating. I'd put the ceramic coating on both sides, and the sound damper on the cockpit side. Then find a closed cell foam suitable as a heat barrier. That foam would work triple duty as a heat barrier, sound absorber and a decoupler for the MLV. Then put your MLV over that. That would all go on the cockpit side as well.

For your floors, and all the flat sheet metal panels, I'd still go with a butyl sheet like the CLD tiles or brand of preference. For the firewall, a liquid like Lizardskin is a good option.

These are just suggestions. Somebody may come along and say I'm bat crap insane, and offer a better heat control solution. Like I said, I'm not an expert in that area.

Lizardskin is a great product and my suggestion, for it's use this application, would be the same. However it is probably the most expensive route.

If Lizardskin is not in the budget then I would suggest an automotive foil-backed insulation. These are usually good to ~700 degrees F of indirect heat and is an excellent sound absorber/decoupler. Use a foil-backed dampener followed by the foil-backed insulation. The combination of these two items will do an excellent job keeping the heat transfer at bay. A good sound blocker, over the insulation, would complete the system.

[jlahl3160]

In addition to what has been already well said by others, flame retardants are added to automotive grade carpet and insulation, using materials without the retardants in significant quantity can add risk.

Also stiffening the flat sheet metal will improve sound inside by raising the natural frequency of the metal panel. The stiffening can easily be done with a powered bead roller – if you know a local sheet metal shop that would help.
13089
or
Using a routed out piece of plywood as a form with ball-peen hammer / bolster chisel..
To see what can be done please see from Thailand…. Incredible work… Time and patience is the key here :
http://vwrides.com/viewtopic.php?t=43&postdays=0&postorder=asc&start=15

I’ve also seen “hydro formed” metal by pounding sand with a hammer and a female die

A manual bead roller .. though not recommended at $180 unless you plan on doing a lot of work this way.
http://www.harborfreight.com/18-inch-sheet-metal-fabrication-kit-34104.html

Less effective, but better than flat, is cross breaking as used in sheet metal duct work.
13088

John

[skullandbones]

I like the idea of adding sound dampening to the aluminum panels but I would be surprised if the panels are as workable for these techniques as aluminum used by FFR. I have begun to do some fabrication with aluminum and have found tried and true methods I have used on other metals don't always work equivalently on the aluminum. I suppose different alloys have different properties but I have to use variations and sometimes completely different strtegies to accomplish cuts or reforming aluminum. It's a different animal for sure. I'm not saying it can't be done just saying based on my experience it isn't as easy with aluminum usually. IMO, WEK.

[NicksPapaw]

For vibration and sound dampening, I used a dynamat type of insulation on the interior panels on my cobra. I also put bed liner on the outside of the panels. Absolutely NO vibrations from the panels. As far as heat is concerned, remember your engine will be in the back and you will be moving forward most of the time. :) Heat transfer on the 818 should be minimum.

[MiniVanMan]

As far as heat is concerned, remember your engine will be in the back and you will be moving forward most of the time. :) Heat transfer on the 818 should be minimum.

I used to repair electronic targeting components of the Apache helicopter. We had a notorious component that would always fail by a few millivolts or so. One day one of my Soldiers asked me what to do about it, so I had him "hold the cable connecting the unit up in the air so the electrons would flow down easier". He held that thing for 15 minutes before coming and telling me it wasn't working. Needless to say we were all busting up laughing.

I tell that story because of the idea that you can "run away" from heat transfer. Heat transfer is not direction dependent. Now, I know what you probably mean by airflow will be moving back across the engine and away from the cabin, but I doubt it will make a significant difference. Treating the cabin against heat transfer is still probably a very good idea.

I may be proven wrong in this regard, and we won't know anything till somebody actually does a test. At this point it's pure speculation.

[RM1SepEx]

For vibration and sound dampening, I used a dynamat type of insulation on the interior panels on my cobra. I also put bed liner on the outside of the panels. Absolutely NO vibrations from the panels. As far as heat is concerned, remember your engine will be in the back and you will be moving forward most of the time. :) Heat transfer on the 818 should be minimum.

Funny, my heat transfer professor would be rolling over, out of control laughing. Both the heat source and the barrier are moving at the same rate. All that matters is the tempature differential, distance, "r" value of the insulation and reflective properties of the surface.

We will have two signifigant heat issues, radiation from very hot exhaust and turbo components and conduction and convection from the heat of the rest of the engine and cooling components.

We will need some sort of reflective surfaced material with some sort of heat insulation to stop that heat from conduction through the aluminum to the interior.

reflective barriers over the turbo and exhaust will make a HUGE difference as would ceramic coated headers, header wraps, and even the stock exhaust shields

[flynntuna]

For vibration and sound dampening, I used a dynamat type of insulation on the interior panels on my cobra. I also put bed liner on the outside of the panels. Absolutely NO vibrations from the panels. As far as heat is concerned, remember your engine will be in the back and you will be moving forward most of the time. :) Heat transfer on the 818 should be minimum.

There's a firewall between the engine and fuel tank, and another between the fuel tank and the passenger compartment. Won't those two firewalls help in both heat and sound transfer to the cabin?

[skullandbones]

There's a firewall between the engine and fuel tank, and another between the fuel tank and the passenger compartment. Won't those two firewalls help in both heat and sound transfer to the cabin?

I didn't think about there being two firewalls. That will give the builder more opportunities to isolate the sound and the heat. I hope people are able to actually measure some sound and heat levels to compare the different methods of insulation. I am definitely going to do some heat measurements and publish but the sound tests will be more difficult. Thanks, WEK.

[NicksPapaw]

[QUOTE=RM1SepEx;79059]Funny, my heat transfer professor would be rolling over, out of control laughing. Both the heat source and the barrier are moving at the same rate. All that matters is the tempature differential, distance, "r" value of the insulation and reflective properties of the surface.

We will have two signifigant heat issues, radiation from very hot exhaust and turbo components and conduction and convection from the heat of the rest of the engine and cooling components.

We will need some sort of reflective surfaced material with some sort of heat insulation to stop that heat from conduction through the aluminum to the interior.

Will all that gasoline sitting between you and your engine not create a bit of insulation? Also, you have a padded seat between the cockpit wall and your azz. That also provides a bit of insulation. In the roadster, you have the exhaust pipe sitting 6 inches from your toes. The dynamat does a pretty good job controlling that by itself. Also, your heat transfer professor probably never stood down wind from a roaring fire vs. upwind. Agreed that they are moving at the same rate. Disagree that moving air does not have an effect on the outcome. Granted, I am not a heat transfer professor, but I have roasted a bunch of marshmallows on a cold windy night. :D

[VD2021]

I really hate to see a good thread move off track.

When nomenclature is misused and members start the "1UP'ing", the OP's topic gets muddied and a good thread fades away.

It would be cool:cool: If we could stop the "1UP'ing and get back on subject.:)

[skullandbones]

I'm imagining what I would do with the thought of a lot of heat generated by turbo heat. I think it is safe to say that a turbo (even a 4) will create more heat than most of the V8s (small blocks) in the roadsters, for instance. That seems to be verified by what I have read in "Maximum Boost" by Proost. He says that heat control of one variety or another is the most important factor in turbo applications. So I would probably apply the Dynamate like product on both firewalls and maybe even spray the lizard skin on the engine bay side. Me being the belt and suspender type would most likely insulate it the same way I did my back cockpit on the roadster. That would help insure heat and sound dampening. I think there is room for that. The center console area would need some extra help for the radiator tubing but that would be easy. All in all, I think the isolation of the heat and sound will be more effective in the 818 than in my present project. Thanks, WEK.

[flytosail]

I used to repair electronic targeting components of the Apache helicopter. We had a notorious component that would always fail by a few millivolts or so. One day one of my Soldiers asked me what to do about it, so I had him "hold the cable connecting the unit up in the air so the electrons would flow down easier". He held that thing for 15 minutes before coming and telling me it wasn't working. Needless to say we were all busting up laughing.

I tell that story because of the idea that you can "run away" from heat transfer. Heat transfer is not direction dependent. Now, I know what you probably mean by airflow will be moving back across the engine and away from the cabin, but I doubt it will make a significant difference. Treating the cabin against heat transfer is still probably a very good idea.

I may be proven wrong in this regard, and we won't know anything till somebody actually does a test. At this point it's pure speculation.

Can an airplane take off if it is on a treadmill? One of you guys are going to get this question wrong.

On a serious note; it would be nice to be able to have a conversation while driving. If a few more dollars and a few more pounds makes this possible then it will be part of my build. I have lost too much of my high frequency hearing (10000 hours of turbo-prop flight time) to afford to risk any more loss.

[MiniVanMan]

Can an airplane take off if it is on a treadmill? One of you guys are going to get this question wrong.



Need more variables. If the plane is stationary relative to the Earth, then no. If the plane is accelerating on the belt, forward, relative to the Earth, then the plane can take off, given velocity matches what the plane needs (slingshot effect). Hell, Captain Kirk achieved time travel by accelerating via sling shot style. If he can do that, surely a plane can take off


On a serious note; it would be nice to be able to have a conversation while driving. If a few more dollars and a few more pounds makes this possible then it will be part of my build. I have lost too much of my high frequency hearing (10000 hours of turbo-prop flight time) to afford to risk any more loss.

This is extremely important to me as well. I won't have my wife fully convinced of how awesome this thing is by the time it's built. So, making sure she can hear me while I laud the abilities and greatness of the car while we're cruising through WalMart parking lots will be invaluable.

Seriously though, I want a car that's snappy, and I can rock out in, or have a nice Sunday cruise without going deaf. The "rocking out" can't be stated heavily enough for me. Audio is a passion of mine, and having a blank canvas to work on with this car, and NOT having to fight with what a manufacturer gave me is another aspect of this car that's infinitely appealing.

[rjh2pd]

Need more variables. If the plane is stationary relative to the Earth, then no. If the plane is accelerating on the belt, forward, relative to the Earth, then the plane can take off, given velocity matches what the plane needs (slingshot effect). Hell, Captain Kirk achieved time travel by accelerating via sling shot style. If he can do that, surely a plane can take off

Well... if its a prop plane, technically it could create enough wind speed over the wings to create enough lift for the plane to take off while it is stationary relative to the earth :p

[flytosail]

“Imagine a plane is sitting on a massive conveyor belt, as wide and as long as a runway. The conveyer belt is designed to exactly match the speed of the wheels, moving in the opposite direction. Can the plane take off?



Back on the quiet part of the thread..... How much weight are we talking about here?

[skullandbones]

Myth totally busted!

You shouldn't worry about a little extra weight because it is going in a very good place relative to CG. This vehicle will have a great CG anyway and putting a little more weight over the rear wheels will be a good thing. I've gokarted my roadster and already a couple of people have mentioned that it has a solid feel to it. I think part of that is the extra insulation and dampening I've included and it isn't done yet. I will put more in the X member under the door and insulate the doors as well to reduce the side pipe noise. On the 818, the additional layers of insulation on the floor will help to reduce road noise (it's close to the ground). Maybe you will be able to enjoy the sterio after all! WEK.

[VD2021]

This is extremely important to me as well. I won't have my wife fully convinced of how awesome this thing is by the time it's built. So, making sure she can hear me while I laud the abilities and greatness of the car while we're cruising through WalMart parking lots will be invaluable.

Seriously though, I want a car that's snappy, and I can rock out in, or have a nice Sunday cruise without going deaf. The "rocking out" can't be stated heavily enough for me. Audio is a passion of mine, and having a blank canvas to work on with this car, and NOT having to fight with what a manufacturer gave me is another aspect of this car that's infinitely appealing.


On a serious note; it would be nice to be able to have a conversation while driving. If a few more dollars and a few more pounds makes this possible then it will be part of my build. I have lost too much of my high frequency hearing (10000 hours of turbo-prop flight time) to afford to risk any more loss.



85dbs of continuous noise will cause hearing loss in the 3000-6000Hz range in a fairly short time. This is where our speech falls. A safe goal would be 75dbs or less.

[tirod]

I'm going back to something said in the beginning - why F5 uses flat panels. I worked in a CNC forming department for a truck cab builder two years, working next to turret punch presses and taking what they made and bending the parts on a 100 ton brake press.

It's all about cost - cutting flat sheets into smaller ones is fairly easy once the program is proofed, you clamp a sheet in, and stand back. Once done, pull them from the table and stack them. Over at the brake press, more labor - sometimes a lot more - but it's still a choreography of bending up the flat sheet until it looks like the part to put into the assembly.

Since the F5 parts are mostly flat sheet, there's no beading, stamping, or reinforcing to stop vibration. The Big Three's do that by forming the part out three dimensionally in one step. We don't, and it's an issue. We can add strategically placed dampener in the high resonance areas, or do something to prevent them vibrating in the first place.

Harbor Freight sells beading machines if that's an option. Learning to operate one, and doing it right, the first time, without damaging the only existing part you have, not so much. It won't be any different sending them out. There will be badly formed parts, and they won't fit. More material will need to be purchased, and the template may be distorted beyond use - so another will have to be made. Some builders already have to do that. Tolerances and final fit up isn't all we'd like it to be, plus a first time builder sometimes doesn't know the finesse points of installing the sheet.

Other materials can be used, which goes to: These panels are NOT structural. They add nothing to the space frame tube chassis design. I even question calling any of the dividers in the cabin a "firewall," considering they don't have any connection to the body, nor do they encompass the entire cabin isolating it from the rest of the car. Using pool noodles, foam insulation, or stuffing foam backer rod into the space between the "firewall" and body doesn't constitute much of a firestop. It will only contribute to the situation, not protect the occupants. Moot point in an open roadster, but it's just the first generation. Ask the Daytona Coupe and GTM guys about it - isolation and air control for comfort is one of the major interior issues.

So, rather than beating on a thin sheet of aluminum, could you substitute that panel with something else that will inherently have more stiffness and vibration resistance, with acceptable strength and weight? Consider UHMW poly panels, or honeycomb sandwich panels. The latter is fairly abundant in salvage yards that specialize in truck bodies - when the delivery truck wears out, the box on the back is usually treated as a cast off, especially if the overhead door is trashed. Those box bodies are also bonded together with VHB tape - which gives enough to soak up vibration and reduce resonance.

Unless you're running undercar exhaust in your build, using composites to build the floor and foot wells is an alternative that could yield a lot of positive results. And, as a quick example of durability, check those plastic corrugated tubs the Post Office uses. The stuff works.

What we are really dealing with is the public's perception of what a quality kit car is - what they expect to work with in building one. What they don't have a clue about is that cars are built they way they are because of mass production economics and costs. Stamping sheet metal pieces and spot welding them together is about the cheapest way to do it, but not necessary the best, no, not at all. It's just the traditional and institutional way to do it. And, since we don't know better, we go along with it. Hence, cool high speed aluminum panels in a kit car. Much better than a integrated interior formed with the body, that crap is so low ball nobody does it anymore. That doesn't necessarily justify using aluminum sheet, tho. It's mostly a cost benefits issue - could we afford precut near aerospace honeycomb structures formed into big pieces? Likely not. That's in the supercar market, the McLaren level stuff. Kinda pricey.

Doesn't have to be if we use a bit of ingenuity. Here's a thought provoker - Observe the masses, do the opposite. If everybody is riveting aluminum sheets onto the chassis tubes, then maybe something else is better.

[skullandbones]

Give the airplane myth a rest, it's been done and is not on subject. Start your own thread and talk about aeronautical engineering. If it was essential to some point in the conversation, I would be all for it but it isn't. It's akind to the argument that if I build my 818 with enough hp, I can outrun the noise in the engine bay! Thanks, WEK.

[Oppenheimer]

how would you attach the 'plastic' panels to the frame? Adhesive? With the Al panels, they are riveted (and caulked), and they also overlap each other. These plastic panels would have more thickness, making overlap more difficult. How would you seal the gaps between each panel?

I'm not knocking it, I just used some of that stuff from an old lawn sign (very similar to post office bin material) to temp patch my roof's Sandy damage while waiting for insurance claim. Its great stuff.

PS - is there a huge fan in front of the treadmill?

[RM1SepEx]

When you bead a panel it distorts it quite a bit... I have access to an Eastwood bead roller and have some experience with aluminum from my electric reverse trike project.

The flat panels riveted to the steel framework is an excellent methos of making a stiff and light structure. The flat panels are poor for sound and the aluminum transfers heat too well though the surface emmissivity does reflect the radiant heat well.

If you want a cool and quiet cockpit you will need to do something. Many good alternatives have been identified above.

re above, just glue the plastic composite to the auminum to make it stiffer...

Noise is a HUGE issue on my trike, with only the electric motor and controller whine the rocks and panel drumming will drive you crazy in about 20 miles! :-)

I will do everything I can to make mine cooler and quieter as it will see most of its life on the road.

[Xusia]

It's always been my understanding that the aluminum panels DO contribute to chassis rigidity and strength. The following passage from FFR's website (about the Roadster) seems to support my understanding:

"By using fiberglass for the exterior body shell and panels only, we removed the stress and significantly reduced the weight while maintaining rigidity with the underlying matrix of ¾” steel tubing and aluminum panels (the right material for the job)."

They are talking about how in the past and/or with other kit designs (by other manufacturers) the fiberglass body was used as a stressed member to increase rigidity. Their kit uses a non-stressed mount for the body, so by definition it can't be adding any rigidity. They maintained the rigidity the body adds in other kits by using aluminum panels instead. At least that's how I read it...

I don't know if it's just me, tirod, but I'm finding your posts increasingly negative and critical. If it was helpful, I think that would be fine. But I don't find them helpful. I'm not sure if you are trying to be helpful or just grand standing. In the post above you are basically insinuating that FFR is using poorly designed parts and/or poor manufacturing techniques, and are advocating people more or less throw that out and do something else (using different materials for the panels). I honestly don't know if you are right or wrong in this situation, but I do know FFR knows far more than me about car design and manufacturing, and based on that I'm not personally inclined to second guess their judgment or try to better their engineering. Upgrades and modifications are one thing, but this is something else - at least to me. Am I alone in this? If so, I'll keep it to myself going forward...

[Oppenheimer]

I do think that one important apsect of FFR choice of Al panels (metal vs plastic) is intrusion. You don't want to run over a muffler or tire gator or something and have it penetrate the cabin. These are primarily street cars, so whatever is used also has to protect the occupants from road debris.

It would be cool if FFR beaded the panels as part of the design, with distortion taken into account so they'd still fit perfectly. But obviously that adds cost. It would be interesting to compare that extra cost to the cost of materials and effort many FFR kit builders use to noise proof their cabin.

I think flat panels they use now would win that equation, especially since most of those looking for quiet would still need to add some sound proofing materials to beaded panels.

[MiniVanMan]

All the beaded panels are doing is reducing resonance. You'll still need the noise blocker. It was previous stated we're trying to do three things, "dampen resonance", "absorb sound waves", and finally, "block the wave". The beaded panel will only accomplish the first of those three. So, effectively, you're just replacing the dampening material with a beaded panel. The benefit to the beaded panel is reduced weight. However, I linked a page where you can see a test done proving the 25% method of damping a panel from resonance. Really, the amount of damping material will not be that much, and therefore not add as much weight as people are expecting. Unless you're running about 10% body fat or lower, you'll be better off going on a diet. Then, as well, the cost will be MUCH cheaper using a material than beading the panel and remanufacturing it to fit properly.

All of this, and then you still have to add your absorber and blocking material, which is where the majority of weight increase is going to come from.

So, beading the panel seems like an awful lot of work to save a few pounds.

Bead the panel, or take a ball peen hammer and tap the panels and find the points of highest resonance and dampen them with an appropriate sized sheet of foil backed butyl product (Dynamat, SDS Tiles, etc)? Seems pretty obvious to me.

[VD2021]

All the beaded panels are doing is reducing resonance. You'll still need the noise blocker. It was previous stated we're trying to do three things, "dampen resonance", "absorb sound waves", and finally, "block the wave". The beaded panel will only accomplish the first of those three. So, effectively, you're just replacing the dampening material with a beaded panel. The benefit to the beaded panel is reduced weight. However, I linked a page where you can see a test done proving the 25% method of damping a panel from resonance. Really, the amount of damping material will not be that much, and therefore not add as much weight as people are expecting. Unless you're running about 10% body fat or lower, you'll be better off going on a diet. Then, as well, the cost will be MUCH cheaper using a material than beading the panel and remanufacturing it to fit properly.

All of this, and then you still have to add your absorber and blocking material, which is where the majority of weight increase is going to come from.

So, beading the panel seems like an awful lot of work to save a few pounds.

Bead the panel, or take a ball peen hammer and tap the panels and find the points of highest resonance and dampen them with an appropriate sized sheet of foil backed butyl product (Dynamat, SDS Tiles, etc)? Seems pretty obvious to me.

Exactly!

The same three part system (with minor material change) will be extremely effective at keeping the heat (or cold) out of the cockpit. Just make the "absorbing/decoupling layer" an automotive insulation (preferably with a foil face) and you're set.

[MiniVanMan]

Exactly!

The same three part system (with minor material change) will be extremely effective at keeping the heat (or cold) out of the cockpit. Just make the "absorbing/decoupling layer" an automotive insulation (preferably with a foil face) and you're set.

Yeah, I see no reason why a foil backed heat insulator wouldn't work as a sound absorber and decoupler as well.

We can beat this to death, and try and reinvent the wheel, but this is pretty much how physics plays out in this scenario.

[Oppenheimer]

All the beaded panels are doing is reducing resonance. You'll still need the noise blocker.

exactly:


I think flat panels they use now would win that equation, especially since most of those looking for quiet would still need to add some sound proofing materials to beaded panels.

[flytosail]

Give the airplane myth a rest, it's been done and is not on subject. Start your own thread and talk about aeronautical engineering. If it was essential to some point in the conversation, I would be all for it but it isn't. It's akind to the argument that if I build my 818 with enough hp, I can outrun the noise in the engine bay! Thanks, WEK.

It was more a commentary on common sense then aerodynamics. However, using your example of more horsepower comes normaly more noise. As fast as this thing will be, it will not exceed the speed of sound. Sorry.

When I visited FFR, I wondered if the aluminum panels that could be covered with powder coating or in extreme cases something like Rinolining. This could solve both noise and corrosion problems.

[edwardb]

I don't know if it's just me, tirod, but I'm finding your posts increasingly negative and critical. If it was helpful, I think that would be fine. But I don't find them helpful. I'm not sure if you are trying to be helpful or just grand standing. In the post above you are basically insinuating that FFR is using poorly designed parts and/or poor manufacturing techniques, and are advocating people more or less throw that out and do something else (using different materials for the panels). I honestly don't know if you are right or wrong in this situation, but I do know FFR knows far more than me about car design and manufacturing, and based on that I'm not personally inclined to second guess their judgment or try to better their engineering. Upgrades and modifications are one thing, but this is something else - at least to me. Am I alone in this? If so, I'll keep it to myself going forward...

No, you are not alone feeling this way.

But moving on. My experience is with the Roadster, but still applies to this discussion. I think two things: The aluminum panels are actually ideally suited for this application. High strength to weight (used in racing and aircraft construction for decades for a reason), minimal tooling, and easily used by DIY'ers like me. I just finished making an all new PS footbox on my Mk4 build. Since I'm installing a SBF, I returned some of the unused space to the passenger by enlarging the PS footbox. The mod is documented on the other forum. I was able to make the new panels with simple tools and it turned out great. Second, I think we tend to overthink this sound and heat insulation issue. At least for the Roadster and the 818, you're dealing with an open top car with a modified and loud engine and exhaust. With reasonable methods for sound and heat insulation, whatever heat and noise is coming from the aluminum panels very quickly goes to the background. I don't have any scientific tests, but for my Mk3 Roadster, I have Lizardskin on the inside of the entire cockpit, and an additional layer of Dynamat over the transmission tunnel. Then the standard FFR carpet in the cockpit and trunk. Real world driving shows the car to have a nice solid feel and overall "hush" from the cockpit. Zero evidence of any "drumming" from the aluminum panels. Everyone who rides in the car is amazed at just how civilized it is. It's just hard for me to imagine that additional layers of various materials are going to make a lot of additional impact. What you do hear is exhaust sound, wind noise, traffic noise (loud on the freeway!) and such. Layers of sound/heat deadening aren't going to change any of those things.

[rjh2pd]

If it was essential to some point in the conversation, I would be all for it but It's akind to the argument that if I build my 818 with enough hp, I can outrun the noise in the engine bay! Thanks, WEK.
I'll be impressed if you can out break the sound barrier ;) But on a serious note, the weight of the insulation will be so tiny compared to everything else. You could save that weight really somewhere else.

[skullandbones]

No, you are not alone feeling this way.

My experience is with the Roadster, but still applies to this discussion. I think two things: The aluminum panels are actually ideally suited for this application. High strength to weight (used in racing and aircraft construction).

It's just hard for me to imagine that additional layers of various materials are going to make a lot of additional impact. What you do hear is exhaust sound, wind noise, traffic noise (loud on the freeway!) and such. Layers of sound/heat deadening aren't going to change any of those things.

My bringing this "additional layers of insulation" up in the first place is to hopefully look at this issue more scientifically. I disagree (in a friendly way) that just because the noise comes from various locations (wind, freeway, etc) that dampening and absorbing the noise from targeted areas will not make a difference in your enjoyment of the cockpit. I believe it can be measured and I guess that will have to be done on a side by side basis comparing various levels of insulation in like projects. I think I can do that since there are a number of roadsters out here that I can compare. I think the roadster builders have pretty much decided that one layer of Dynamat and carpet is the maximum you can do to avoid unwanted noise because of the openness of the cockpit, generally speaking (don't waste your time). Any variants to that general belief will usually be dismissed as a "pissin contest". But there is a little more to sound abatement than that. So I plan on isolating it to the point that I can say, "now the only thing that bothers me is that sound coming from outside the door on the left side but just a little bit". Anyway, if there is an improvement, it can be transferable from project to project. Thanks of your input, WEK.

Note: removed some of edwardb comments to focus on my point.

[MiniVanMan]

I think it's also important to note that a 3db increase in volume is double. i.e. 75 db is half as loud as 78 db. Our ears are really only sensitive to 10 db differences at that point though. So, for us to actually hear double the sound output, we'd have to jump from 78 db to 88 db.

I don't remember, (first page) somebody stated hearing loss can result from a sustained 85 db at frequencies 2000 hz and above. You can look at a human being's typical hearing "bell curve" and see where we're most sensitive to sound. 2000 hz - 6000 hz is the apex of the bell curve. We don't hear higher frequencies as well as the midranged frequencies, but higher 10k-20khz is where we lose our hearing first. Typical human hearing is 20hz - 20,000hz (20khz). I challenge anybody 40 years old or so to actually hear a 20 khz sound wave. You're probably effectively deaf at the frequency, and very likely all the way down to 15khz.

Now, I say this, because when we look at noise and the cumulative effect of noise on our hearing, we need to understand how to protect ourselves. Now, in an open roadster, the main source of noise is likely going to be wind. That wind may drown out other sources, but it doesn't mean those other sources are completely quenched. Without going into constructive and destructive interference, I'll say that noise can accumulate. Because a certain frequency is drowned out, doesn't mean that it's not present enough to actually cause an issue.

Here's a typical hearing curve, or "Fletcher-Munson Curve".

http://img.photobucket.com/albums/v641/glevii/fletcher.jpg

So, we can see that we're most sensitive at 2-6 khz. That just means a 4 khz signal of 60 db will be louder to us than 60 db of 8 khz. Same amplitude, different perception. If we look perceived sound between 4 khz and 10khz, it's almost a 20 db difference. That's 3 times the "perceived" volume for the same amplitude, based on a 10 db perceived doubling of volume. What that means, if you have 75 db of noise at 4 khz, and 75 db of noise at 10 khz, the 4 khz is going to completely drown out the 10 khz. However, we're much more susceptible to hearing loss at higher frequencies. So, we're more likely to sustain hearing loss from the 10 khz at 75 db than we are 4 khz at 75 db, even though it's not as prevalent to our hearing.

Sound is subjective to many people. Hearing loss is a heavily studied science. Your perception doesn't always match up with the science. So, while I think it's accuarate to say "well, I only noticed a difference up to this point with my acoustic treatment", it's not accurate to say, "since I only noticed an effect up to this point, that's all you need". You need a lot of measurement equipment to actually determine that.

If somebody has that data, it would be EXTREMELY helpful to this thread, and I'd be very interested as well as I'm sure others.

[VD2021]

MiniVanMan,

Again, as throughout this thread you and I have been tracking on the same page.

I would only add (as FYI) that the 3khz-6khz at ~60dbs is where we speak and hold normal conversation.

Also, that the sum of all present sound is cumulative to the total SPL.

[Xusia]

So, while I think it's accuarate to say "well, I only noticed a difference up to this point with my acoustic treatment", it's not accurate to say, "since I only noticed an effect up to this point, that's all you need". You need a lot of measurement equipment to actually determine that.

Now THAT was well stated!

It's not relevant to this thread, but I'll provide a side note because it's ironic. I'm over 40 and have a hearing problem, but it's not hearing loss. The problem is actually that I have excellent hearing (up to over 20 KHz!). Because of this, sounds that other people tend not to notice much ("background" sounds like fans, road noise, etc.) can drown out voices and as a result I have hard time understanding what people are saying (I can hear them talking, but I can't make out all the words). My wife (of course!) didn't believe the first doctor, so I had to go see a second one! LOL! She SWEARS it's selective, but it's honestly not.

[edwardb]

My bringing this "additional layers of insulation" up in the first place is to hopefully look at this issue more scientifically. I disagree (in a friendly way) that just because the noise comes from various locations (wind, freeway, etc) that dampening and absorbing the noise from targeted areas will not make a difference in your enjoyment of the cockpit. I believe it can be measured and I guess that will have to be done on a side by side basis comparing various levels of insulation in like projects. I think I can do that since there are a number of roadsters out here that I can compare. I think the roadster builders have pretty much decided that one layer of Dynamat and carpet is the maximum you can do to avoid unwanted noise because of the openness of the cockpit, generally speaking (don't waste your time). Any variants to that general belief will usually be dismissed as a "pissin contest". But there is a little more to sound abatement than that. So I plan on isolating it to the point that I can say, "now the only thing that bothers me is that sound coming from outside the door on the left side but just a little bit". Anyway, if there is an improvement, it can be transferable from project to project. Thanks of your input, WEK.

Note: removed some of edwardb comments to focus on my point.

That's fine. My real world experience -- not theory -- is that the simple treatment is actually very effective. If there is a better approach, which can be proven, I will be very interested.

[Evan78]

It's not relevant to this thread, but I'll provide a side note because it's ironic. I'm over 40 and have a hearing problem, but it's not hearing loss. The problem is actually that I have excellent hearing (up to over 20 KHz!). Because of this, sounds that other people tend not to notice much ("background" sounds like fans, road noise, etc.) can drown out voices and as a result I have hard time understanding what people are saying (I can hear them talking, but I can't make out all the words). My wife (of course!) didn't believe the first doctor, so I had to go see a second one! LOL! She SWEARS it's selective, but it's honestly not.Wow, that's interesting. I have a similar problem with making out speech, but I've never sought any diagnosis. I've always assumed it was something mental and related to ability to focus selectively. In noisy environments such as a bar, club, or even noisy restaurant, I seem to be well below average in making out what people are saying, even though I don't seem to have any hearing problems otherwise. I don't seem to have any above average abilities like hearing things others can't or being bothered by noises that others don't notice.

[skullandbones]

I'm hoping to get some feedback from roadster drivers when I actually get mine registered. I know Mesa Mike is pretty active in the valley and I think I can get him to participate and he has a slew of friends out there. I know the sound measurements are mor empirical but sometimes the perception one has of the cockpit environment is "telling". If there is a concensus over several persons, that can, at least, contribute to the quality of the sound if not the quantity. We'll see. WEK.

Note: My wife swears I can tune her out like tuning out a certain frequency so that when watching sports, especially football, nothing interupts me. So she repeats, "Bill, Bill, Bill, Bill............." until I answer her. WEK.

[Xusia]

Wow, that's interesting. I have a similar problem with making out speech, but I've never sought any diagnosis. I've always assumed it was something mental and related to ability to focus selectively. In noisy environments such as a bar, club, or even noisy restaurant, I seem to be well below average in making out what people are saying, even though I don't seem to have any hearing problems otherwise. I don't seem to have any above average abilities like hearing things others can't or being bothered by noises that others don't notice.

As I understand it, there is another common problem that begins to happen to men as they approach 40, which is the part of the brain that deciphers spoken word begins to have trouble doing it's job (I'm not sure how else to explain it since I'm not a doctor and don't understand it). This has an effect similar to to what I described above in that you can hear people talking, but can't make out what they say as well as you used to. If you think this may be the problem, I'd see an audiologist. I don't think there is anything they can do (like me, amplifying sounds only makes the problem worse), but you never know. Maybe they can treat it now, or maybe it's something else...

[Slatt]

Wow, that's interesting. I have a similar problem with making out speech, but I've never sought any diagnosis. I've always assumed it was something mental and related to ability to focus selectively. In noisy environments such as a bar, club, or even noisy restaurant, I seem to be well below average in making out what people are saying, even though I don't seem to have any hearing problems otherwise. I don't seem to have any above average abilities like hearing things others can't or being bothered by noises that others don't notice.

Weird, I've never heard anyone else describe my own problem. I've always had that, just like you describe. I attribute it to some sub-version of the ever popular ADD. Sorry to maintain the Off Topic topic...

[skullandbones]

Haven't thought about the various forms of hearing loss but it does give us the opportunity to pass on the inherrent risk in hot rodding. For those like me, who didn't wear hearing protection for drag racing events, went to too many rock concerts and sat too close to the giant speakers, working around high pitch and loud power tools, etc it's a little late. But if you can mitigate the sound issues enough to keep the damage to a minimum and still enjoy the activity, it's worth it.

I'm working on my doors now. On some projects that may not seem like a focus point but on the roadster, it is right next to where the side pipe exhaust exits. So I'm planning on opening an inspection "window" in the inner shell to do some more insulation. A lot of people will think that's not effective because you can reach your arm over and touch the side pipe from your normal cockpit position. However, it may act as one more barrier for the unwanted sound to numb your ears on an extended outing. So just out of curiosity, has anyone done that for a roadster? I started thinking about this when others were discussing the reinforcement (side impact devices) in various FFRs. There is nothing in the MKIII but air. So now the "Hushmat" (Dynamat style stuff) and foam are options that I am considering. Any thoughts? Thanks, WEK.

[Xusia]

My first thought is to avoid expanding foam. Only because once you do it there is no going back - it's kinda in there and not easily removed if you need to make a repair or want to change something.

As far as doing it vs. not, sound travels in straight lines, only changing direction when bouncing off a reflective surface (reflective as it relates to sound). Therefore if the door is between your ear and the pipe, it will have an impact. Sure, some sound will emanate in other directions, bouncing off buildings, other cars, etc., and still reach your ears, but you will have reduced the sound coming from the closest and most direct source. Definitely worth doing IMO.