Adapters

Exhaust adapters join parts that do not meet directly: pipes of different diameters, a flange to a plain pipe, or one pipe to two. You will find reducers, fitting sleeves, universal adapters and flanges here, as well as X- and Y-pipes, in stainless and mild steel.

Gas flow loses energy at every sudden change in cross-section. An abrupt step from a small pipe into a large one creates turbulence and a pressure loss, while a gradual taper lets the flow slow down or speed up smoothly. A reducer with a cone is therefore kinder to the flow than a small pipe pushed into a large one and welded over.

In a slip joint, the pipe from upstream should sit inside the downstream one. The gas then flows past the seam instead of being driven into it, so the joint stays tighter and cleaner.

Pick by the joint you need:

• Reducers: 127 to 101.6 mm, 101.6 to 88.9 mm and 101.6 to 76 mm. Some are listed with a length of 200 or 270 mm.
• Fitting sleeves: 220 mm long for 101.6 mm pipe and 260 mm long for 127 mm pipe, in stainless or mild steel, for joining two pipes of the same size.
• 2.5″ adapters: universal adapters listed with a second dimension such as 40, 60 or 80 mm or 10 cm, some with a three-bolt flange. A triangular flange and a 49 mm donut flange are listed too.
• X- and Y-pipes: stainless X-pipes in 50.8, 63.5 and 76 mm, and Y-pipes that split one pipe into two of the same size, at 50.8, 63.5 or 76 mm.

Measure the outside diameter of both parts before choosing, because inch-based and metric sizes are close but not always interchangeable. A slip joint needs a clamp that seals all the way round, such as a band clamp, and a high-temperature exhaust paste helps it seal from the first start.

Tack a welded adapter in place and check the alignment of the pipes on both sides before welding it fully. Soot traces at a joint after the first drives show where it needs more clamping or fresh paste.