Rocks in your exhaust?

[yankeedoodoo]

Heard one of those automotive legend stories recently. Goes to the effect of Mazda(?) was unable to get one of their race cars quiet enough to gain admittance to an event a few years back. Out of desperation they alledgedly put some sort of volcanic rock into the exhaust. Did the trick and no further problems. Has anyone heard this tale and, of course, could it be true? What sort of rock might be involved? The glassy sharp stuff would seem heavy and of dubious value in suppressing noise. Tufa is light and gets me to wondering.....

 

Noise IS an issue way over here in CA.

 

TIA for any responses, including ridicule leveled @ the poster!

[Stationary M25 Traveller]

Pumice is very light.

 

7 related photos

[peterg]

That would have been the Mazda 787B rotary engined cars entered at Le Mans in 1991 with Johnny Herbert as one of the drivers and winning it - they were VERY LOUD 😬

 

There's even a soundtrack on Youtube

 

Edited by - peterg on 5 Dec 2007 08:46:27

[Sheds Moderator]

You can get pumice to foam, in fact it is naturally a foam. The insulating blocks used in buildings are also a foam, which accounts for their lack of mass, high insulating factor and the impossibility of hanging anything heavier than a small picture on them. . I'm sure a similar Rockwool or rock foam product would do a similar job. I wonder who might make it?