3 1/2" EMT for exhaust?

[prototech]

Hey guys,

I was wondering if any one has ever used 3 1/2" EMT conduit for exhaust pipe or knows of any reason not to? the reason I ask is that they are throwing away a whole dumpster full of 3 1/2" conduit at work, so I can buy enough to do my exhaust for a couple bucks and there are several mandrel bent 90* bends. So I do the math:

Cheap ******* + Lincoln welder + almost free conduit = new 3 1/2" exhaust system for a 92 DODGE CTD!

+ bonus wife can't be too mad 'cause its cheap!

Proto

 

[hdm48]

I like your math.

But I've never heard of anyone doing that. But it's free,, right? worth a try? YUP. Let us know how it works out.

Special note; do not throw away your old pipe.





Dave

 

[dpuckett]

The tailpipe may not matter too much, but how heat tolerant is the stuff? Seems to me it wouldnt last too long as an exhaust pipe farther up. I went to the local Freightliner dealer, and got some pieces of 4" stuff to make a "custom" 4" system for my rig. Gonna install it tomorrow, if it dont rain.

 

[1stgen4evr]

conduit

If the conduit has galvanizing, be very carefull about welding. Fumes from galvanize will cause immediate throat irritation and can lead to chemical pneumonia within hours. This I know from experience.



Find someone who needs the conduit and swap for exhaust material if you can.



1stgen4evr

James

 

[sparks57]

I think that's why exhaust pipe is relatively thin, to shed heat.



A friend of mine worked at a store that sold all kinds of steel, and he used thinwall tubesteel.



But then again, that was the Ferd I had to tow all the way from Bellvue...

 

[EZGZ]

Prototech

Go for it. All you are doing is guiding exhaust gases with a tube.



That conduit is real garbage and should never be used for anything structural. It is unsafe.

But for experimenting with exhaust it will do fine.

As was mentioned be careful not to inhale the smoke when welding.

You can cut it in the bends and get all kinds of weird angles. Can't say that the welds will make for great flow.



At high temperature the coating will blister and peel. It will rust faster than a good mild steel exhaust tubing.



But what the heck it is free so have some fun. It dosen't hurt to snoop around the dumpsters at the muffler shop now and then. They screw up bends and throw stuff away. They may even bend it for you and swedge the end for cheap.

 

[Philip]

If you use galvanized pipe or EMT tubing. Make sure you put it no where close to something that can burn. Galvanize coating is made up of 95% zinc with 5% alumin for brightner. It is applied at a temp of about 650 degrees. Once the pipe reaches close to that temp the gal will start to go liquid agin. Around 700 it starts to give off fumes and glow. Around 750 degrees it starts to burn. It burns hot.



I worked in a galvanizing plant for two years.

 

[tugboatphil]

"So I do the math: Cheap ******* + Lincoln welder + almost free conduit... "



Proto!! You and I must have had the same math teacher! I love the way you think!!

 

[jlast]

ALREADY DONE MY FRIENDS, including a full system from turbo to exist at the rear behind the tires.



Questions and pics are available just ask.



total costs was like $50 or so, i bought three mandrel bends two for the downpipe and one for the turnout, and i bought three SS band clamps. ALL other bends were pre bent electrical bends. I was on a job and dang bender was messing up i brought home about 80' of 3 1/2 emt with all different bends. I can tell you exactly how i did mine, what bends and offset you need to clear the transfer case, using stock hangers, etc... . But the rear pipe by the spare tire is a B**** and i decided i would not carry a spare, it might fit but it would be a pain.



Took about four days, but two days were trying to figure out how to use the bends i had to go in the rear section and make sure i could use the spare tire.

 

[prototech]

hey jlast,

how about them pic's? have you had any problem with rust or blistering of the galvanizing? I think I am going to stick with the stock down pipe, it's in good shape, and I am think'n on modifying the angled frame bracket to avoid doin' the offset bend thing. any how, glad to see I'm not the only cheap ******* out there!

Proto

 

[jlast]

I will try and get some tomorrow its suppose to be nice. I will send them to anyone that asks. I will include little detail and then let you ask away. It wasnt exactly done cause i was cheap it was i had the emt, stock exhaust was smashed in two places, and i had the time. I would rather have a emt exhaust over any flex anywhere in the exhaust, imo.



BTW i have been stocking up on 4" emt which doesnt match 4" exhaust but its bigger.

 

[jlast]

got 9 pics available and more if you need something specific,



Send me and email with your email account that will take pics.



total is 1. 25 mb in size, i can send just a few or can divide them up.