911 muffler.

jbird · 04-30-2013, 04:11 PM

Made an aluminum muffler for my 71 911 the other day on the cheap and thought I'd share a picture. First I made 2 flanges from an old exhaust gasket template and tapped them 1 1/2 NPT. Cut 4 pieces of 1 1/2 aluminum pipe and threaded the ends for the inlet pipes and outlets that come out the back. Used a 3" aluminum conduit with the bend already done . Photo has steel caps on but I have since turned up some aluminum ones. I stuffed it with insulation packing and then screwed on the caps. If you want to change the sound or packing you can unscrew a cap and pull it out the end. Sounds good and weighs next to nothing. I TIG welded the joints in a few spots just in case. Has plenty of clearance and costs very little.

sc_rufctr · 04-30-2013, 04:14 PM

Nice workmanship but being alloy how long would it last?

Az911 · 04-30-2013, 04:19 PM

Post a vid once you have it installed.

jbird · 04-30-2013, 04:20 PM

Not really sure. I made the flanges plenty thick and the conduit is heavy enough wall thickness that i dont think it will ever get hurt. I threaded and welded the joints because I wasnt sure what the heat expansion would do to them. I have been driving it for about a month now and nothing has cracked or come loose. Certainly not going to rust!

Guardsred911 · 05-01-2013, 04:38 AM

Right on.... That's tremendous..

noavgdrvr · 05-01-2013, 04:41 AM

sound clip please

schumicat · 05-01-2013, 05:28 AM

isn't the packing restrictingh the flow? on most mufflers the exhaust is changing direction but it isn't blocked, or there are double walls and the packing is inside the outer wall.

tobluforu · tobluforu's Garage

That's a trip and a half, looks like a pipe bomb, is it loud?

Geronimo '74 · 05-01-2013, 05:37 AM

More pics!
Look great, simple and lightweight!
I like!

H-viken · 05-01-2013, 05:38 AM

Quote:

Originally Posted by Az911

Post a vid once you have it installed.

+1

Very creative!

IROC · IROC's Garage

It would be funny if it showed something like a 20hp gain on a dyno.

Elombard · 05-01-2013, 09:12 AM

LOL Mike ^

Yes I would Like to see pics installed and a sound clip if you can manage? Very cool.

Dublinoh · Dublinoh's Garage

Quote:

Originally Posted by Guardsred911

Right on.... That's tremendous..

+1 nice

aoncurly · aoncurly's Garage

Won't you have dissimilar metals (aluminum and steel) in contact with each other at the flanges? I think this will accelerate the corrosion of the steel flanges and steel bolts.

manbridge 74 · 05-01-2013, 11:53 AM

Motorcycles have had aluminum mufflers for years, so if you've got the correct alloy it might do alright long term. Use a copper flange gasket and no dissimilar metal issue.

timmy2 · timmy2's Garage

Now that is what I would call a banana muffler...

1-ev.com · 1-ev.com's Garage

nice

Jerome74911S · 07-27-2013, 01:03 PM

Have you tried other types of packing yet? Is the whole thing simply packed full? What type of packing, exactly, is in there now?

jbird · 07-27-2013, 01:22 PM

I have a white boiler type insulation in there that is wrapped inside of foil screen wire. Just got out of it actually. I will try to post a sound clip. It isnt packed clear full by any means and you can make it louder or quieter by changing how full you stuff it. Its a little racey but heh its a 911 not a Prius right?

jbird · 07-27-2013, 01:27 PM

Quote:

Originally Posted by IROC

It would be funny if it showed something like a 20hp gain on a dyno.

It actually seems like it freed up the motor and makes more power as funny as it may seem. The car had two individual shorty mufflers on it and they were sooting up my bumper and I didnt like the sound anyway.