4inch aluminum exhaust

just wondering what you guys think of the idea. im sure at my power level the 3 inch is restricting a little and i just feel like doing something new. SS DP bc the heat, but switch to aluminum underneath. should cut weight in half and sound a bit diff.

I doubt you’ll notice a HUGE sound difference with FI, but it sounds like a good idea to me

I’d do it just for the weight

do it

well how about you guys look around and help me find a nice 4 inch muff. all i could find was a vibrant one… bends to, i found some but always looking for a deal

I had a vibrant muffler before and they seem to work pretty decent. Keeps the sound down a bit

Vibrant makes a great product… I’m sure they are the cheapest you will find. I would just buy everything through them.

brooks I had a 4" exhaust on my VRT. the vibrant muffler I put on was awesome! highly recommend it.

Out of the turbo is 3in so idk how much your going to see difference power wise

you’d be better off with a cutout. ive seen a handfull of single turb cobra guys with a 4in alum downpipe, they all ran it open. but the weight savings would be the biggest benefit i feel. annnddd you have given me an idea my friend…

i had a vibrant on my m3 and it sounded pretty good to me. i agree with the sticking with vibrant idea.

You’ll likely be making this out of 6061, which start to melt at about 1050F on the surface. That’s less than half the temp required for typical 304. However, thin wall section tubing(~16ga) ca start to deform or collapse bad at around 750F so you need to make sure you carry your stainless back far enough to avoid that type of heat. Hard to guess how far, only real way to do it would be to take laser thermo readings of your current exhaust while on a dyno pull and that would get you a ballpark distance to work with.

Can and has been done before, but every setup is different. Just don’t want to see a nice exhaust turn to mush on your first pass.

Worst case build it, make some dyno runs and test temps then. Can always cut and make a slip joint SS extension of the DP if needed. At least aluminum tubing/bends is cheap if it goes poof :tongue

Go baller and run a titanium exhaust!

Quit stealin my ideas. :ponder

Depending on how long the aluminum section is, you wont need one (minus nysinsp). the soft properties aluminum has actually acts like a muffler by itself. Aparently the sound waves are somewhat absorbed by the aluminum and it muffles the sound a bit.

Look up EVO aluminum exhaust on youtube. I saw a clip a while back when i was lookign into this too. It was SS DP into aluminum tubing back to the bumper, straight piped and it sounded like a normal cat back 3" SS did.

Adam is spot on, gotta find the temp where it will hold up. Also keep in mind, that SS has poor thermal conductivity, meaning it takes a while to pick up the heat, but will hold it in longer as a result. Since aluminum is the opposit, it will absorb the heat faster and also as the car is moving, the air passing over will wick it away quicker too. What I am getting at is say the SS DP is around 800F say 3 feet past the turbo (safe for heavyer aluminum) you might be able to get away with startting the aluminum around 2.5 or so or maybe less.

Or I am completely backwards and you will need to start it 4 feet away… LOL but I think you get the idea.

I say screw the exhaust and put an auto trans in it! 3spd, manual valve body, trans brake, etc

talk to Arod, hes got an aluminum exhaust on his race car. last i heard it, it sounded pretty awesome. the aluminum construction does alot for muffling it as well

He has it going through the hood now . Thing sounds mean with no muffler.

thanks for the help guys. i’ll let you know when i get going on it

ps- anyone interested in a K-teller 3 inch with magnaflow muff for a HB? or a 3 inch top mount DP with vband

I had aluminum exhaust on 1st front mount turbo kit in '04 … it melted and deformed like crazy… at least for 1-2 feet coming off my downpipe.

how thick was the aluminum piping you were using?