The B58 in the M340i and M240i pulls hard everywhere. The factory airbox just is not built to show it off. BMW fitted an intake resonator whose only job is to cancel turbo and intake noise, and the box itself leaves room on the table for a bigger filter.
The Dinan Carbon Fiber Cold Air Intake for the BMW G42 M240i and G20 M340i rebuilds the whole lower airbox, not just the lid. The box is 60% larger than stock, the filter grows from 82 to 115 square inches, and Dinan measured 58% more airflow than the factory system. On the dyno that is up to 9 wheel horsepower at 6500 RPM and 8 lb-ft at 6000 RPM.
How the Dinan Carbon Fiber Cold Air Intake Avoids Heat Soak
The worry with any open intake is heat soak: hot engine bay air creeping in and costing you power. Dinan wanted a secondary inlet to fill the larger airbox, so it tested several opening shapes, sizes and locations with one goal. The added inlet could not raise intake air temperatures. The final design brings in more air without that penalty. The factory resonator is gone too, so you now hear the turbo and blow-off sounds BMW worked to hide.
The airbox is 100% genuine carbon fiber, not a wrap over plastic. It looks right in the bay and it sheds heat instead of storing it.
Dinan M340i and M240i Intake Fitment, Braces and Legal Status
One thing to check first: this version is not compatible with factory or aftermarket strut braces. If your car has a brace, or you plan to add one, Dinan sells a retrofit lid and hardware kit that fixes it. It is also not legal for sale or use in the State of California. Dinan lists it as Emissions Code 7, legal under the EPA Tampering Policy outside California, with CARB testing pending. Install takes about one hour, and Dinan backs it with the remainder of the factory limited warranty (up to 4 years or 50,000 miles) or 2 years with unlimited miles, whichever is greater. Dinan part number D760-0052. Sold by AutoTecknic, an authorized Dinan dealer.
What's Included
- Carbon fiber intake box assembly
- Custom free-flowing filter
- Installation hardware
Key Features
- Dinan-tested 58% more airflow than stock
- Dinan-tested gain of up to 9 WHP at 6500 RPM and 8 lb-ft at 6000 RPM
- Entire lower airbox redesigned, 60% larger than stock
- Filter area 115 sq in vs 82 sq in stock, 40% more
- Secondary inlet tested to add air without raising intake air temperatures
- Factory intake resonator removed for more turbo sound
- Real carbon fiber construction
- About 1 hour bolt-on install
Vehicle Fitment
Fits the following B58-powered BMW models:
- BMW M340i / G20 Sedan (2020-2026): M340i, M340i xDrive
- BMW M240i / G42 Coupe (2022-2026): M240i, M240i xDrive
Not compatible with factory or aftermarket strut braces without the separate Dinan retrofit kit. Not for the G22 M440i or four-cylinder 230i and 330i models.
Installation Notes
Plan on about one hour with basic hand tools. Remove any strut brace before you start, and do not reinstall it unless you have the Dinan retrofit kit. Follow the Dinan instructions included with the kit.
- Let the engine cool and remove the engine cover.
- Unplug the air mass meter connection and loosen the intake clamps.
- Remove the factory airbox, filter and intake resonator.
- Install the Dinan carbon fiber airbox and filter and secure every clamp.
- Reconnect the sensor, start the engine and check for leaks and warning lights.
