repacking mufflers

[kaido]

has anyone repacked a muffler to reduce noise?

my daily has a full stainless system that unfortunately has one of those terrible cannon exhausts, I don't so much mind the look but its rather loud, so I was thinking, maybe I could cut the chamber open and repack it, then weld it back up, to quieten it down, rather than spend money on a new muffler.

anyone have experience with this? packing methods?

[mattysshop]

it would be cheaper to just fit a proper muffler OR fit a centre - centre oval muffler under the car somewhere.. that way you wouldn't have to change to much..

[kaido]

not really, proper mufflers aren't free.

im thinking of opening it up having a look, if its packed fairly tight, I could theoretically quieten down with a looser pack.

[mattysshop]

as you will be opening it up and re packing, you have a grinder/drop saw, and a welder...

both of which are required to simply install a brand new $60 supercat center - center mild steel muffler...

[kaido]

fair enough mate, but some people prefer to do things themselves. I was hoping with the immense knowledge on this forum, that some one surely would have attempted something like this before, and share some wisdom before I give it a crack...

Being able to build mufflers wouldn't be a bad skill to have, later in the year I will be building a custom one from scratch for the cafe racer I'm building, simply for it to be unique and the exact design and dimensions I want.

[TERRA Operative]

The gear to do it will probably end up working out close to the cost of a new muffler, and it may or may not work....
The muffling capabilities aren't so much from the amount of packing, but more the total size of mufflers.

By all means try it out, but be aware that more mufflers is the tried and true way to yield definite results.

[RT40Corona4AGTE]

I would have to agree with TERRA on this one.

it comes down to total size for capabilities.

[kaido]

Thanks TERRA for a proper answer,
Id have to add a nice stainless mid muffler though, be a shame to cut up a full stainless system and patch in mild steel. last time I checked magnaflow was about 200 for something stainless and decent sized, but i was looking at replacing the cannon rather than adding a mid muffler

Ill have a look though. I could probably replace the inner perforated stainless tube, with smaller diameter, then repack. it would reduce flow a little, but its not a race car so it doesn't matter too much... and i'm sure its better than keeping the shitty silencer I have in there at the moment anyway.

[TERRA Operative]

Check out getting Magnaflo from the states. With the good exchange rate, it'll probably end up being cheaper from the US.

If you have the time and tools, by all means, give it a go. Be sure to measure the sound before and after (1m away from the tip at 45deg towards the side of the car, as per the ADR test procedure) so we can get a comparison. I'm interested.

[banana_socks]

Had a bit of experience with this at our FSAE comp. Most teams build their own mufflers, and I reckon they're one of the hardest things to do properly. Ours was basically a cannon, with fibreglass matting around a perforated steel tube. Lasted about 4 laps before it was shooting out chunks of the fibreglass. We had to repack it after every session, it was hopeless. Wasn't just ours, the majority of the teams had to make last minute modifications because they were too damn loud. Try if you must, but its not something I'd bother with.

Weld on flanges to your pretty stainless to allow a mild one to bolt in?

[kaido]

Thanks banana, that does put things in perspective.

[TERRA Operative]

A lot of commercial mufflers have steel wool wrapped around the perforated tube to keep the fibreglass in.

[Sam_Q]

I thought the more packing it had the better it did it's job?

[kaido]

Im not too sure but from what Ive been reading about custom built motorbike mufflers, the tighter the packing the less cavities and hence the the sound waves will have less tendency to get through and out of the main pipe?

but then again i'm sure not enough packing would also result in inefficiency of the muffler too.

[me217]

why not just buy a variable flow gate, thing, not sure there name. but i've seen em for sale on the mr2 site. just fit it in your cannon, so its nice and quiet when putten around and opens up when you give it a boot full.