180 Degree Mandrel Bend 321 Stainless Steel; 2.50 in. Tube O.D.; 3.75 in

Exhaust tubing that lives next to a turbine housing sees heat that slowly fatigues ordinary 304 stainless, which is why turbo fabricators reach for 321. Vibrant states that its 321 bends outperform 304 between 800°F and 1500°F and resist the stress cracking that appears around welds after many heat cycles. Part 13828 is a full 180 degree U-bend in that alloy, with a 2.50 in O.D., a 3.75 in centerline radius and an 18 gauge wall.

Why start from a mandrel 180

Mandrel forming supports the tube from the inside while it bends, so the inside diameter stays consistent through the curve instead of flattening the way a crush bend does. A 180 also gives you the most usable material in one piece. Cut it into two 90s, a 60 and a 120, or several short segments for a downpipe, a turbo crossover or a dump tube that has to wrap tightly around a crossmember.

18 gauge or 16 gauge?

The 18 gauge wall on 13828 keeps weight down and is the usual choice for downpipes and exhaust runs downstream of the turbo. Vibrant also makes the same 2.50 in by 3.75 in CLR 180 with a heavier 16 gauge wall as part 13848, which some builders prefer for manifold runners and hot pipes that support the weight of a turbo or wastegate. When TIG welding 321, back purge the tube with argon and use a stabilized filler such as ER347 so the weld holds up as well as the base metal.

Frequently Asked Questions

How is 321 stainless different from 304?

321 is a titanium-stabilized grade, which helps it hold strength and resist cracking along the weld zone at sustained exhaust temperatures. Vibrant cites better performance than 304 from 800°F to 1500°F, the range a turbo exhaust spends a lot of its time in.

What does the 3.75 in CLR mean for packaging?

Centerline radius is measured from the center of the bend to the middle of the tube. On a 2.50 in tube, 3.75 in is 1.5 times the diameter, which gives a compact U-turn that still flows well and fits around frame rails and steering shafts.

Can I bend the tube further after it arrives?

Mandrel bends are finished shapes and are not meant to be re-bent by hand or on a press. Cut the 180 into the angles you need, then tack and weld the pieces to change direction.

Fitment: Universal. Confirm the sizes and thread types listed above against your application before ordering.