Interesting Exhaust Discovery

[Drewmotty]

I’ve been struggling to prevent the long middle box on my TR4 from rattling so as the exhaust note was very subdued I gave up and replaced it with a piece of straight pipe expecting a fruitier exhaust note. 

Now running with a relatively small single tailpipe box the exhaust note seems not to have changed a bit. 

Can anyone educate me on the black magic which is occurring here?

[stuart]

You`ll probably find the reason the box was rattling was all the filling had gone out of it thats why replacing it doesnt sound any different.

Stuart.

[RogerH]

1 hour ago, Drewmotty said:

I’ve been struggling to prevent the long middle box on my TR4 from rattling so as the exhaust note was very subdued I gave up and replaced it with a piece of straight pipe expecting a fruitier exhaust note. 

Now running with a relatively small single tailpipe box the exhaust note seems not to have changed a bit. 

Can anyone educate me on the black magic which is occurring here?

That is an interesting discovery. 

When fitting mine I was not impressed at all with the middle box arrangement.

Come the spring I may well remove it.

 

Roger

[John Morrison]

On my TR4 I removed the rear box, then lengthend the middle pipe so I could run the long box

further down the car, worked well for me for years.

John.

[badhuis]

 

My car became noisier over the years. Cut open the middle box and all the packing was gone. I filled with stone wool (house isolation stuff, available at DIY stores) and welded it shut. Excellent sound again, not too loud. So far so good (done a couple of months ago).