Turbo manifold question

[Aschle]

For those of you that have built turbo systems, I am interested in knowing how the turbos are held securely. I would think that there must be some type of bracing to hold the weight and not put that stress on the manifold bolts. Am I thinking correctly, or overthinking it ?

Thanks

[camcojb]

Originally Posted by Aschle

For those of you that have built turbo systems, I am interested in knowing how the turbos are held securely. I would think that there must be some type of bracing to hold the weight and not put that stress on the manifold bolts. Am I thinking correctly, or overthinking it ?

Thanks

Always a good idea to have a brace on the turbo if possible. Usually it seems the tubing and/or welds crack from the weight, plus heat cycling and vibration. When the turbo is further out location-wise it gets tougher to design a brace. I will tackle this when I get my front drive and can see what mounting options are left.

I did find some universal brace pieces on Google:

https://www.google.com/search?q=turb...w=1242&bih=568

[Blown353]

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...

[CJD Automotive]

You definitely do not want the header to support any weight other than itself. The turbo needs to be supported, whether from the bottom or top. They make oil drain adapters, it's a spacer that you weld on a support structure to support the turbo. The spacer bolts between the turbo and oil drain.
Sometimes you don't have room on the bottom. In my case, I only had room to hang the turbo's. I designed a stainless bracket:


That would center the weight of the turbo, and used a high temp rod end:


I attached this to a rod with a threaded tube end. This allows me to fine tune the placement.


You'll want either double slips on the collector (best way IMO) or a bellows, to allow expansion of the header to turbo. You'll want the same for the waste gate.

[Aschle]

Thank you guys for the replies, definitely good information given !!!