Do I need some of these?

[chevynut]

I have a header to bumper stainless exhaust system all TIG welded together from straight pipe and mandrel bends. It's a long system with an x-pipe, and I've always wondered if I should have a pair of these in the pipes to try to isolate engine movement from the rest of the system. Do you think I need these?



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[MP&C]

Are they on the new Vette's? If your system is rubber isolated and has room for movement I wouldn't worry. If it looks like you may experience some noise due to exhaust in close proximity to frame members, it may be a good idea.

[chevynut]

Thanks Robert. My exhaust currently has rubber hangers but I'm looking to replace them with some billet ones with urethane isolators to make it a bit more rigid. It can still move, though. I have urethane engine mounts so the engine shouldn't move too much. My concern was the length of the pipes that are all welded together, and the stress on the welds. I don't want it cracking.

[Rick_L]

If your hanger system allows some axial movement you're good. When things get constrained - well then something has to give.

They are done both ways, as well as some other variations.

You can calculate the added length, I don't think it's that much because the pipe is only hot up by the engine.

[chevynut]

Rick, with most of my exhaust being stainless it will expand almost 50% more than if it was steel (9.6 in/in/F versis 6.7 in/in/F). I thought those coupling bellows were for vibration, but maybe they're for expansion.

My first hangers will be 32" from the header collectors which are about 2 feet from the center of the engine. If I assume the exhaust cools from around 1200F at the port to 600F in that distance, it should expand about 3/8" at the first hanger. That's a lot imo. Now if we assume the rest of the ~7 feet of pipe drops to 200 degrees at the exhaust tip you get another ~1/4 of an inch expansion. That's 5/8"!!! Are these temps reasonable?

So how do guys get away with bolting their exhaust with hangers that don't allow for this much axial expansion? I see it all the time.

I'm thinking that I need to make these billet hangers slide on some studs rather than bolting them solidly in place even with the urethane bushing.

[NickP]

[Rick_L]

I think your temperatures are a good guess for peak temps, but normal temps would be down quite a bit from that.

If you cut your expansion estimates by about 1/2 to 1/3, now you're getting into things that are more manageable.

[rockytopper R.I.P 5-13-2017]

Those look awesome Nick. Were does one acquire them?

[chevynut]

Nick, how does that system deal with expansion of the pipes the way you have it bolted up?

Rocky, look here: http://www.deedsengineering.com/

I just ordered some myself.

[NickP]

There are a total of 8 Deeds clamps.