Large exhaust on a budget

[jeffreydmet]

I have read several accounts where people really wanted a large exhaust but didn't really want to spend the $400 to buy one.

Here's what I did. I, like a lot of you have more time than money. I went to an electrical supply house and bought one length of 3" thinwall electrical conduit and 2 of the large radius elbows for this size pipe. It is called 3" but is really 3.5" od. In about 4 hours with a little welding and some torch work I had the old exhaust off (but could put it back on) and a new 3.5" mandrel bent straight pipe on. I used a piece of 1/2" rod I had laying around to make new hangers since I thought If I were to sell the truck I might want to put the stock pipe back. I didn't tackle the down pipe yet.

Bottom line is though, I have a large exhaust pipe for $56 bucks. Not bad huh?

[DmaxMaverick]

Cheap, but comes at a price. That pipe is probably galvanized or zinc clad. The zinc on the pipe will burn off, exposing the bare steel underneath making it vulnerable to the elements, salt, etc. It will also fume off a toxic vapor. You probably noticed it when you welded on it (a lot of stinky white smoke).

If you keep the system, I'd suggest the following. In a well ventilated area while wearing a respirator, torch the pipe from the forward most part to about 2/3 the way back. If you have a shop fan available, use it, as the stink will stick around if given a chance to accumulate in the cab.

Exhaust pipe (tubing) is normally bare steel, aluminized, or stainless steel. The reasons are due to the heat, and corrosion. The pipe you've used is no better than bare steel after it has burned off.

Good luck!

[jeffreydmet]

I also figured it would burn the galvanize off leaving bare metal. However with the large exhaust the pipe runs a lot cooler. I have about 5000 miles on it since I put the pipe on including a trip to Florida pulling my camper. Surprisingly the pipe looks the same as when I installed it.

I do frequently fabricate things out of Electrical conduit since it is a cheap source of tubing. I have heard of people being affected by the zinc but I always do the welding in a well ventilated area and have never had any problems.

[Bigg R]

I used conduit mandrel bends on rear section of
the tail pipe on my 95 3500.Then bought the straight section from my downpipe to the tailpipe
at a truckpro dealer.Then coated the entire system with exhaust coating from Eastwood!
This exhaust has been on my truck for 2yrs.and
still looks good!! Only real cost was the downpipe
I bought from Schied Diesel!

[GARY PAGE]

Great post, your thinking!!!

[pannhead]

thrifty and crafty are good charactor traits :D ..i know moondoggie would agree :D

[kowsoc]

The zinc stink? :D Whatever was going to burn off is probably gone already.
Harmfull? :D There's probably more carcinogens in the diesel exhaust going through the pipe.
Rust? I think you'll be good for a few years.

Enjoy! ;)

[Dvldog 8793]

howdy
RE: "zink stink"
As the owner/operator of a welding and fabricating shop I can tell you that welding of galvanized metal IS harmfull. I don't like to do it and WILL NOT do it in a enclosed area. The main problem that seems to happen is the hinges on the bathroom door get loose from the constant use! :D IT IS some bad stuff and will really mess up your day. I don't know about the long term problems but they for sure can't be good.
In regards to your rust issues, when i do have to weld on Galvmetal I always recoat with a spay on cold galvanize finish. This is applied to bare metal. When I put on my exhaust(3 salt-infested-winter ago) I painted my muffler and all my welds with it. NO rust yet.
Have fun and wear a mask if you have to weld that stuff. ;)
L8r
Conley

[moondoggie]

Good Day!

pannhead: I

[Bigg R]

I've always heard if you drink milk before you weld this stuff, your stomach problem will be greatly reduced,this is what I did-no problems!
Plus I welded it outside that helped!!

Bigg R

[Beedee]

Re: Welding galvanized steel.
Bad, Bad stuff.
When you cut and weld on galvanized steel, you are releasing cadmium to the atmosphere, that is the same stuff that is in a lot of rechargable batteries that everyone is trying to keep out of the landfills because it is so toxic.
If you must use galv metal, wear a properly fitted resperator, not just a mask.
Any welding fumes are toxic (read the literature that comes with the product). Respirators are cheap, and with a proper cartrige will last for years. Do yourself a favor and get one if you are going to do anymore work with galvanized. :D

[Turbine Doc]

Here's another thought & less welding if you live where they ain't real fussy about appearances.

Whitney's sells flex exhaust in Galv, 300 or 400 series stainless at reasonable prices, works good for bypassing Cats. (can I say that on TV) ;) or making a test pipe for such purpose. It's pretty durable especially in the stainless, stainless wrap around clamp connectors for the joints/elbows make for easy install-remove.

It does not work so well for IC tubing come to find out after the fact; only rated to 3 psi, I had to rethunk it after oil started migrating past the flex seams under 15 psi boost pressure.

I have solid steel tube there now, all better, but flex steel HVAC tube rated to that high can also be found so GTCTD tells me.

[kowsoc]

No offense at all guys ;) My point was that the fumes are probably burned off already...on front of the pipe where exhaust temps are higher. I have brazed galvanized metal before and I know the fumes that come off are VERY harmful (green smoke can't be good). Actually, all welding smoke is harmful.