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Old 12-07-2020, 01:06 AM
Blown353 Blown353 is offline
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Bracing is a very good idea and mandatory if you want your system to last, but you also want to make sure the bracing allows things to move for thermal expansion... stainless has a fairly high CTE and moves around quite a bit.

Making a super-rigid brace that holds the turbo tightly is a guaranteed way to quickly crack the tubing leading to the turbo, because the bracing won't be able to move to accommodate the movement of the tubing as it changes temp. Same goes for supporting the turbo off a frame-mounted brace-- that puts a lot of stress on things when the engine moves under torque but the frame doesn't. Something's going to give, and it's the tubing.

Heim joints, skeletonized hangars that allow flex in the direction of thermal expansion but are rigid vertically to support the weight of the turbo, etc, are all your friend. My personal preference is for a truss-type hangar made of tubing with heim joints supporting the turbo weight to allow movement, and a small skeletonized bracket at the turbo to minimize heat conduction into the heim joint... many good examples of just that kind of arrangement in the link Jody posted above.

In addition to bracing, flex/expansion joints help relieve stress quite a bit too, but you have to make sure you get couplers rated for "hot side" turbo use. Many of the braided style flex joints will fail rapidly on the hot side of the system. Most hot-side rated expansion joints are bellows style with a tube slip joint inside, they allow linear expansion/movement but don't really tolerate axial misalignment or movement. There are also a lot of cheap expansion joints out there made of Chinesium that will rapidly fail...

Finally... material selection. 304 is often used on the hot side because it's cheaper and a bit easier to work with, but 321 is a better choice since it better tolerates high temps and will have a longer service life. 321 is quite a bit more expensive and there are fewer suppliers.

OEMs have been using a great idea for long term durability on turbo engines for a while now... they cast a single outlet "log" style exhaust manifold into the cylinder head and bolt the turbo directly to the head... lots of strength to support the turbo, a very short exhaust path for less heat loss and faster spool, and no hot-side tubing to fail over time. Not really an option for most builds though...
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Last edited by Blown353; 12-07-2020 at 01:14 AM.
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