All aluminum exhaust piping

[Mitsu725]

I am considering fabing up an aluminum exhaust from the DP back, truth is I am actually going to try and make an AWD replica of an exhaust for my fwd, I hate the bends the Fwd has to go thru. I was just wondering since we have done 2 track cars out of aluminum exhaust but Like I said they are track cars and don't ever see day to day driving. My car doesn't see daily driving either but it does see driving every weekend. I am wondering if it will hold up to the heat. I mean I am using a stainless DP but after that I would like to go with 16 gauge aluminum. What do you guys think?

 

[THE_ARTIST_]

you mean a aluminum cat back? should be ok i would think.

 

[Mitsu725]

yeah kind of like a catback, We don't really run cats down here. We use just straight piping from the downpipe all the way to the back of the car like a 3" ID 3 1/2 " OD aluminum pipe.

 

[Dsmj89]

It will be just fine. My friend has a full exhaust system fabbed up from a shop out of aluminum from the o2 back and so far so good, and his dsm is daily driven.

 

[Boosted98gsx]

just remember that Al melts at 660*C. Any DSM under load will reach that temperature.

 

[tkelly27]

I'd be concerned with how it's mounted to the hangers. Short ones are probably ok, but as you start to get longer a factory style with the hangers welded to the pipe itself would probably have fatigue problems. With the welded on bracketry (welding automatically makes Al weaker), high heat, and potentially having it trying to resist high force loads I could see it failing.

If you had a steel clamp or basket or something to hold it up, with rubber to isolate the steel from the Al, I could see that holding up ok.

 

[Mitsu725]

Maybe I could fab up something like a drive shaft loop to support the exhaust or different style hangers... and wrap it with some thick plastic or similar that won't melt . And I thought aluminum dissipated heat really fast?

forgot to add I will post up some pics when I start making this exhaust...

 

[tkelly27]

It has to reach the temperature it's dissipating to dissipate it. Heat goes through aluminum really well, it conducts heat through itself well. That doesn't change the temperature of the stuff going on inside or the ability of the cooling medium to take away heat.

I like the drive shaft loop idea, it will keep it fixed in a certain position much better. The factory just used heavy duty rubber, so you could probably get away with that. There are two factory hangers on either side of the pipe, you may be able to modify them to be used like the DS loop or cradle.

I'd like to see pictures when you are all done, and how it works out for you. I had considered it when slapping together my exhaust, but I didn't have a TIG machine together to do it.

 

[daren_p]

My question is how are you making a replica awd exhaust on a fwd? The awd is a more straight route because the gas tank has a big hump through the center, for the driveshaft, rear end, etc. The fwd tank doesn't have this, which is why the exhaust is routed around the tan. So what are you planning, to run the exhaust under the tank? (wouldn't recommend it)

 

[slowgsr]

just remember that Al melts at 660*C. Any DSM under load will reach that temperature.

Your correct, pure aluminum in its element state. However, aluminum quickly gets an oxide film on it, that raises the melting point to 2200deg +.

People do make aluminum downpipes as well.

Im not saying the heat wont have negative effects, but the weight savings is huge, especially if he dosen't drive the car everyday. I AM saying it will NOT MELT.

Goodluck. I would love to do an aluminum exhaust myself.

 

[slowgsr]

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For all the haters. Good detail in the pics above, especially with regards to hangers.

 

[tkelly27]

Wow, that's amazing!

You are right about the film but what happens is you get a film with a very high resistance to heat with liquid aluminum underneath it. If you put a oxy torch (or a DC TIG torch) to a piece of aluminum you'll see the skin start to float and new skin form. As soon as you take the heat off you can fold 3/16" aluminum like you would a piece of paper even though it looks normal on top.

That's obviously a drag race only application. I wouldn't make a down pipe out of it for a DD, but it clearly works there, and you've clearly shown that it can be done.

That hanger is what i'm talking about. Unless you heat treat it, the weld zone in the hanger on that last pic is 1/4 the strength of regular aluminum and I imagine it would be a failure point for a street unit. It's got a pretty big moment arm from the pipe and the length of the hanger on it too. Just a bad combo for long term aluminum life.

I never thought I'd see something like that, very cool for racers, maybe I'll have to plan on aluminum exhaust for my van : D I still say a steel down pipe for street use though.

 

[talonDSMerr]

That's some good information! But isn't the 4g63 head made of aluminum? What keeps that from melting under load or normal driving? It's not an alloy is it?

 

[Boosted98gsx]

That's some good information! But isn't the 4g63 head made of aluminum? What keeps that from melting under load or normal driving? It's not an alloy is it?

It also has coolant, oil, and very frequently cool air running through it to keep it below 600*c.