Exhaust Tubing Info

[johnnyweb]

we have been experiencing alot of exhaust tubing breakage on our race truck. i looking to go to a better quality tubing. we have been just using standard aluminized steel. im thinking of using stainless or ?. any body have any info on this ?. we have tried all different ways of mounting and brackets etc and it still ends up breaking. every other race or so.

[025]

Check with Burns Stainless in Costa Mesa. Should be able to help.

[mfs]

are u running stock motor mounts? rubber hangers? if so i think some more semi soild mounts (motor, trans & exhast) will solve your problem.

[matt_helton]

i agree. solid mount everything and it will hold together. and when you think you have enough hangers on the exhaust, mount 2 more.

[billymanfroy]

Johnny,

304 stainless. We used Burns for the collectors I think and SPD in Rancho Cordova for the tubing. I paid about $550 for ALL the various pre-bent tubing for the headers with some left over and it was all 304 stainless. The engine, mufflers and trans are solid mounted, and so far the only thing to crack was the passenger side muffler where they stamped "Dynomax" in it. I can't remember the tig filler our guy used, but it was like $900 for 10 lbs.

[johnnyweb]

we are running the auto fab motor and trans mounts which have a urethane leafspring type bushing in them.so the motor and trans have very little give. i have tried stock rubber band type hangers. i know have it mounted with small urethane bushings with very little give or flex in them and it still broke like 3 times at the nev 1000. we run jba headers on it and they have been trouble free so far. (BILLY) what is the contact info to get some exhaust tubing to work with? im thinking of using stainless tubing and adding a flex joint up by the header collector.

[johnnyweb]

also the tubing seams to break close to the header most often. im thinking the extreme heat is breaking down the metal?

[billymanfroy]

SPD (Specialty Products Design):
http://www.spdexhaust.com

.pdf catalog: http://www.spdexhaust.com/#catalog

11252 Sunco Drive
Rancho Cordova, CA 95742
916.635.8108
Toll Free: 888.778.3312
info@spdexhaust.com

Burns:
1013 W. 18th St. Costa Mesa, Ca 92627
949-631-5120
fax 949-631-3184
http://www.burnsstainless.com/

Both are top-notch companies to deal with.

Good luck!!

[ntsqd]

Sounds to me like the hanger lay-out is limiting the thermal growth of the system. Put in the hangers such that the system can expand with heat w/o inducing any tension on the system.

The heat from welding is far more extreme than anything in the exhaust. What you could be getting is chemical corrosion or something akin to hydrogen embrittlement, or a combo of both, from the exhaust gasses combined with the exhaust heat.
Have you tried using the non aluminized tubing? The very tiny amount of aluminum that ends up in the welds could be setting it up for failure. Not likely, but possible.

Some other options:

Run an OE type flex section at the collector. These are stainless steel bellows with a stainless wire over-braid on them. They will break after a while, so pick a standard size and install them with flanges. I got 3 years out my first one on Patch, my chaser/explorer/occasional DD yota w/ stock engine mounts. I'd think you could get up to a season from one in a race truck with a more rigidly mounted engine.

A friend of mine always tore out the rubber hangers on his J$$p. He used 3 links of chain. One mounted to the frame and the opposite attached to the exhaust. The trick is to install them so that the link in the middle isn't flopping around. Been on there several years now w/ no problems, or noise.

[johnnyweb]

im thinking over the different ideas. i know for sure i will go to some different tubing. and i think i will incorporate flex tubes out of the collectors. can stainless be mig welded or is it a must to tig weld it?? i dont have a tig welder but im sur i can have a buddy weld it up that does.

[FABRICATOR]

Are you using "slip-on" or solid welded collectors? There is alot of difference between the two.
Damn, I was about to scrap out a few hundred pounds of SS TIG rod. Guess I better see what kind it is first. lol

[ntsqd]

The flex sections I've used had mild steel bushings on them so welding them to common exhaust tubing is no big deal.

A trick I learned is to step the flanges. In other words, move the flanges upstream from the end of the upstream tube. To do this means that the downstream tube has to be expanded for a slip-fit over the upstream tubing and the downstream flange has to have it's center hole opened up appropriately. I step them roughly .5"-.75" from the end. No leaks and no gaskets, just a small bead of Ultra-Copper. My 'glass buggy's exhaust has been like this at the muffler flange for going on 15 years with no leaks.

If it's 308L I'll take some off your hands so that you don't have to scrap it. ;)

[roach]

they should not be braking no matter what material you are using. some material is stronger than another, but i dont think that is your problem. you have bind somewhere or something is solid while another wants to move.....i.e. solid motor mounts and loose hangers or the reverse. do you have to force any of the tubing lets say, if you removed the flange from the header???

[johnnyweb]

if i remove the pipes from the collectors they seam to be align good the bolts go right in and the flange on the pipe fits the header flange pretty darn flush. the exhaust has been routed out threw the bed sides. so the pipe has to make quit a few bends in that area to sandwich between the frame and the bottom of the bed. i plan on eliminating that and shortening the pipes and just dumping the exhaust out under the frame or something to just make thing smaller lighter and easier to mount. we were using the small 90 deg angle mounts with the small rubber or ? (not sure on material) donuts that are like 3/8 thick. i can under stand the tubing breaking at the welds but it does not break at the welds every time. it has been speratic where it breakes but more times then none its broke up near the joint of the header where it makes a bend and turns along side the transmission. the guy that does my exhaust work for me is a great guy he sponsors me all the work but he does not know much about offroad racing so he really is not much help in design. i am going to find out what kind of stainless he gets or the # on it if it is not good stuff i will get some tubing from the guys billy used for his and i guess just try again incorporating some ideas that we have discussed. thanks johnny

[scottm]

Stainless, like 304, is definitely better than steel, but either will work. Your cracking may be due to thermal expansion. Steel grows by about .080" per foot for 1000° F of temperature rise. Stainless moves about 60% more, or .130" per foot per 1000 F. The best mounting method to account for thermal growth is a slip joint, with one end of a length fixed, and the other end free to expand in a slip joint. For example, consider the engine side of a header to be fixed. Then mount the header end of the collector solid, with the header free to slip inside. Then mount the other end of the collector so it is free to slip into the muffler or other joint.

[FABRICATOR]

Hastelloy-W is good for stainless exhaust. With any stainless tube joints, make sure you either purge it good and/or make the joints tight with tiny welds. Otherwise you end up with a scale model of the Himalayas inside. (TH, got plenty of 308 come by and grab a bunch.)

[johnnyweb]

let me try to understand this growing thing. so what you are saying is flare one side of the pipe and slip the other into it and mount the pipe on both sides of the joint but do not weld the joint together just let it expand and contract on its own. or maybe pull the pipes together with springs like a 2 stroke motorcycle pipe? or a small retainer bracket to hold the pipe inside the flared (larger) pipe? i talk to my exhaust guy and he said the pipe he recomends is 409 he said it is a mix of stainless/iron and is more flexable then 309 stainless. any body heard of these types of tubing? again thanks for the input feel free to keep it coming.

[scottm]

409 is a good choice, it is a low alloy, low cost stainless, and is what the carmakers usually use for exhaust parts.

There are many ways to do it, but what I have seen work well is to mount the female pipe rigidly near the joint and leave the male pipe free to, um, move in and out with the thermal growth. You dont need it at every corner, just 1 or 2 key locations to allow growth and prevent cracks. It won't make a perfect seal, so be aware and make sure exhaust doesnt get into your parker pumper.

[ntsqd]

Or you can use the flex couplers that I mentioned above in place of the slip-joints.

Also, be advised that 409 does 'rust', it takes on a patina that looks like rust. However it does not appear to pit like carbon steel does. Look at any of the tubular manifolds used on late models to see what the patina looks like. Not a big deal, just don't expect that it will look like 300 series.

[johnnyweb]

it looks like ill either go for the slip joints or flex sections. and use the 409 stainless. ill also shorten the system to save weight and just use turn outs instead of piping it up over the frame and out the bed sides. we will see in october at vegas to reno. cross your fingers it sure would be nice to remedy this issue!

[FABRICATOR]

Here is a quick reference chart for welding rod (mostly stainless). http://www.isan-metall.com/Delivery_programm/Long_Products/Welding_Consumables/welding_consumables.html