BMW Turbo Downpipe Gasket 4" - N20 N26 N55 B46 B48 MINI Cooper - 18307581970

OE replacement turbo-to-downpipe exhaust gasket (4") for BMW N20, N26, N55, B46, and B48 turbocharged engines, plus select MINI Cooper S and BMW i8 models. Direct replacement for BMW OE part #18307581970. This crush-style gasket seals the turbocharger exhaust outlet connection, preventing leaks and maintaining exhaust efficiency. Single-use - replace whenever the exhaust connection is separated during service.

Gaskets Required Per Vehicle

All vehicles listed below use a single-turbocharger setup and require 1 gasket per vehicle. Sold individually - order 1 gasket per turbo outlet.

Key Features

• Direct OE replacement for BMW part #18307581970
• 4" diameter crush-style exhaust gasket
• Seals the turbocharger exhaust outlet to downpipe connection
• Prevents exhaust leaks and maintains engine efficiency
• Fits N20, N26, N55, B46, B48 engines (BMW) and B38 (BMW i8 / select MINI)
• Compatible with stock and aftermarket downpipes
• Single-use crush seal - replace at every exhaust service

Specifications

Vehicle Fitment

What's Included

• 1x Turbo-to-downpipe gasket (4", OE #18307581970)

One gasket per vehicle - all listed engines are single-turbocharger.

Why Replace This Gasket?

This is a single-use crush seal and should not be reused. The gasket deforms on initial installation to create the seal - once compressed, it cannot create the same airtight bond a second time.

Reinstalling an old gasket can cause:

• Exhaust leaks at the turbo-to-downpipe connection
• Reduced engine efficiency and turbo response
• Unwanted exhaust noise, ticking, or hissing
• Check engine lights from O2 sensor readings

Always replace with a new gasket during exhaust, downpipe, or turbo service.

Need a Different Size?

OneFastShop offers turbo-to-downpipe gaskets for other BMW turbocharged engines:

• 3.5" Gasket (OE #18307553601) - for N54, S55, S58, N63, S63, S68, N74 engines (M3, M4, M5, M8, X5M, X6M, 750i, etc.)
• 4.5" Gasket (OE #18328612538) - for B58 engines (M240i, M340i, M440i, 540i, 740i, 840i, X3, X5, Z4, Toyota GR Supra)

Match the gasket size to your engine before ordering.