The larger-bore exhaust flange part number 18111712070 fits several higher-displacement or performance-oriented classic BMW models between 1985 and 1995. It is used primarily as a heavy-duty exhaust joint connector at the catalytic converter to mid-muffler section for the following chassis configurations:
BMW 5 Series (E28 & E34 Chassis)
- 1988 BMW M5 (E28) – Hand-built performance sedan with the 3.5L S38 engine.
- 1989–1993 BMW 535i (E34) – Equipped with the 3.4L M30 inline-6 engine.
- 1991–1995 BMW 525i (E34) – Fitted alongside the smaller
18111712064 flange on the dual asymmetric piping of the 2.5L M50 inline-6.
- 1993–1995 BMW 530i (E34) – Small-displacement 3.0L M60 V8 configuration.
BMW 6 Series & 7 Series (E24 & E32 Chassis)
- 1985–1989 BMW 635CSi (E24) – Late-production luxury coupes with the 3.4L M30 engine.
- 1987–1989 BMW M6 (E24) – High-performance coupe utilizing the 3.5L S38 powerplant.
- 1988–1992 BMW 735i & 735iL (E32) – Large executive sedans sharing the 3.4L M30 inline-6 track.
Note - I have 2 different flanges which look almost identical. Fortunately, the part numbers are etched on the flange. The 18111712064 is a slightly smaller diameter flange designed to wrap around standard 45mm to 48mm exhaust pipes. It is matched with standard-displacement 4-cylinder and smaller 6-cylinder exhaust tracks. The 18111712070 is a larger diameter flange designed to match thicker 50mm high-flow exhaust piping configurations. It features a broader internal opening to clear large-bore tubing.
