Exhaust Flanges & Gaskets

Exhaust flanges and gaskets make the bolted joints in a system: manifold to downpipe, turbo to pipe, or one section to the next. Alongside them, the section holds the pipe and fittings used in the same jobs, such as straight pipe, reducers, spacer sleeves and compensators, in stainless and mild steel.

A flanged joint seals only as well as its clamping load and the flatness of its faces. Heat cycling works against both: the flange grows and shrinks, the fasteners relax, and a thin flange can bow between its bolts. A three-bolt pattern spreads the load more evenly around the joint than two bolts do.

The gasket fills the small irregularities between the faces. Once it has been crushed and heat-cycled, it cannot be relied on to seal a second time.

Match these details to the joint:

• Bolt pattern: two-bolt and three-bolt flanges, some with the gasket included or with a sleeve for the pipe. Separate three-bolt gaskets are listed too.
• Wastegate flanges: two-bolt 38 mm inlet and outlet kits, made for one external wastegate series, so check them against your wastegate.
• Engine-specific flanges: stainless turbo and particulate-filter flanges are listed by engine in the title, often by engine code. Check that code against the engine itself rather than the car model.
• Pipe size: from 44.5 mm (1.75″) to 89 mm (3.5″), including 57, 63.5 and 76 mm.
• Pipe and transitions: straight pipe in 0.5 m and 1 m lengths, straight reducers such as 63 to 76 mm, triple-step reducers and spacer sleeves.
• Material: stainless or mild steel. The flange pipe connectors are made from 409, a ferritic stainless grade widely used for exhaust parts.

Fit a new gasket every time a joint is opened, and clean both faces back to bare metal. Check a welded flange with a straight edge, because welding heat can pull the face out of flat; a skim or a file restores it. Put high-temperature anti-seize on the studs and tighten the nuts evenly in steps, so the flange pulls down square.

Re-check the nuts after the first heat cycles, once the gasket has bedded in. A ticking at cold start that fades as the engine warms up is the classic sign of a leaking flange.