Anyone Ask About Interior Noise?

[NSTG8R]

Well we know Eastern Catalytic will be supplying the entire exhaust system. We will just have to wait and see what it sounds like however I am sure IAV knows exactly how much back pressure the system will create and have taken this into account in the engine design. The exhaust will exit at a bit of an unusual location as the muffler is actually located under the passengers' feet with the exhaust exiting under the car near the right frame rail.

Man! That looks awfully close to the ground!

 

[goldwing06]

Man! That looks awfully close to the ground!

looks like a speed bump snag!

 

[Edward43]

Jim, this is an excellent question!

As you already said we really don't know for sure at this point and the prototypes until now have not actually had any sound deadening material in them so that does not really help us. Having said that I expect the Elio will do quite well as it has several advantages.

The biggest advantage I see is the fact that two out of three wheels are not located within the structure and the only one within the structure is not driven as well as being underneath both a layer of insulation and the one piece floorpan so this should reduce road noise quite considerably. Slippery aerodynamics should cut down on wind noise and the SMC composite body panels are naturally better at sound deadening than metal panels.

So all that tells me that even with standard econobox insulation the Elio should still be very quiet for an economy car.

I am also a little concerned. I drove an old Saturn that was horrible for noise. I also have flown a Piper Cub that was bad because of the tail wheel, and fuselage design which is similar to the Elio. The Elio body design houses the rear wheel within the shell. I would not expect it to be difficult to insulate that rear seat/wheel well area. The other points of concern would be front suspension, and motor mounts, which could become an issue over time as the mileage increases. To win public support it should be within reason for sure.

 

[NSTG8R]

I am also a little concerned. I drove an old Saturn that was horrible for noise. I also have flown a Piper Cub that was bad because of the tail wheel, and fuselage design which is similar to the Elio. The Elio body design houses the rear wheel within the shell. I would not expect it to be difficult to insulate that rear seat/wheel well area. The other points of concern would be front suspension, and motor mounts, which could become an issue over time as the mileage increases. To win public support it should be within reason for sure.

I've got one laying around here somewhere, but here's some 'semi-related' info [since you mentioned 'fuselage'] that might be handy...and it's free by mail, or in PDF form. I've gotten a lot of stuff from these guys.

http://www.aircraft-spruce.com/catalog/bvpages/soundproofmanual.php

 

[goofyone]

Man! That looks awfully close to the ground!

looks like a speed bump snag!

I think it just the angle of the photo as the vehicle is not actually exceptionally low to the ground. The P4 has 4.25 inches of ground clearance, however it is lower than stock on purpose for photographic reasons, and the final vehicle is supposed to be at 5.75 inches of ground clearance which is the same as a Mustang.

 

[goofyone]

I am also a little concerned. I drove an old Saturn that was horrible for noise. I also have flown a Piper Cub that was bad because of the tail wheel, and fuselage design which is similar to the Elio. The Elio body design houses the rear wheel within the shell. I would not expect it to be difficult to insulate that rear seat/wheel well area. The other points of concern would be front suspension, and motor mounts, which could become an issue over time as the mileage increases. To win public support it should be within reason for sure.

The Elio panels are a much nicer material than the Saturn panels. The Saturn panels were in essence polymer reinforced ABS plastic which was cheap but really not very rigid so thanks to their flex actually contributed to interior noise. The Elio panels are fiberglass reinforced SMC composite, which is essentially what newer corvettes have used for the last 15 years, and this material is stiff enough to contribute a good bit to structural rigidity and also has some sound absorption properties while being about half the weight of steel panels.

Any ordinary car houses all four wheels within the shell so reducing that down to one should easily cut down on road noise. Plus as I said the floor pan is one piece, runs over the rear tire, and I am sure will be covered in sound/temperature insulation so it should provide a nice sound barrier preventing much road noise from entering the cabin. Also with such a small cabin owners should be able to add any extra insulation quite easily if they so choose.

Motor mounts are pretty well sorted out at this point as cars produced in the last decade plus very rarely wear out their motor mounts within the first 100,000 miles and as Elio is using off the shelf components I don't expect it to be any different. Suspension materials are also pretty well understood at this point and rarely create issues anymore so once again with off the shelf bushings and such I doubt there will be any major issues prior to whatever the whenever the shocks need to be replaced.

Having said all that this is all just theory based on what we know about the materials and EM's designs. We will have to see exactly what plays out when the rubber actually meets the road.

 

[JEBar]

I am sure IAV knows exactly how much back pressure the system will create and have taken this into account in the engine design. The exhaust will exit at a bit of an unusual location as the muffler is actually located under the passengers' feet with the exhaust exiting under the car near the right frame rail.

I have no doubt that the component manufactures are working together .... its easy to see how the sound of the exhaust could be heard inside the vehicle .... I wonder if the location of the end of the tailpipe has anything to do with the rear windows not being designed to open

Jim

 

[Smitty901]

At 6800 to 10 K I am sure it will not be a Limo ride as far as noise goes . But that is not what it is meant to be.

 

[goofyone]

I have no doubt that the component manufactures are working together .... its easy to see how the sound of the exhaust could be heard inside the vehicle .... I wonder if the location of the end of the tailpipe has anything to do with the rear windows not being designed to open

Jim

The exhaust had to exit here because the fuel tank is in the way under the passengers seat and it would have cost more to route it further back. I am sure there will be extra heat insulation between the exhaust and floorpan so hopefully this will help with any extra exhaust sound under there.

As far as I know the rear windows not opening is simply a cost consideration as we have been told that venting windows are likely to be an option.

 

[goofyone]

At 6800 to 10 K I am sure it will not be a Limo ride as far as noise goes . But that is not what it is meant to be.

Exactly, the Elio does have some advantages over a many economy cars which should help reduce interior noise however it is still an economy car so nobody should expect this car to be as quiet as a Lexus.