Presenting a world first – the Eventuri Hybrid Airbox System, a breakthrough intake solution for the iconic BMW E46 M3. This system delivers the aggressive, race-inspired sound of the CSL airbox while retaining the seamless drivability and plug-and-play simplicity of a traditional intake.

Previously, E46 M3 owners seeking the CSL airbox sound were forced to run the engine without the MAF sensor, often requiring costly ECU conversions or remaps that negatively affected throttle response and overall drivability. The Eventuri Hybrid Airbox eliminates this compromise, providing the sound and power of a CSL airbox without the need for a remap, while maintaining the drivability and smooth performance delivery of a conventional intake.

The E46 M3 airbox uses Eventuri’s patented Venturi carbon-fibre housing, which provides an aerodynamically efficient airflow path. This is not merely another cone filter with a heat shield, but a unique design that invokes the Venturi effect and maintains laminar flow conditions to reduce drag on the engine. 

This Eventuri airbox has been independently dyno tested by Dream Automotive in the UK. Tests were conducted back to back against the stock airbox, with several runs performed for each configuration. The dyno results show a consistent gain throughout the RPM range, attributed to the smoother pathway through the intake and airbox to the throttle bodies. On the road, this performance gain translates to improved part-throttle and full-throttle response, with the car pulling far more eagerly to the redline.

Eventuri provides all the parts required to install the airbox and get the car on the road. With typical CSL-style airboxes, additional components are usually needed — such as an ECU tune and breather pipes. Since this airbox retains the OEM MAF sensor, no aftermarket tune is required, and the necessary breather hoses are included. Below is a cost breakdown of the additional parts normally required for CSL-style airboxes. The only item needed in this case is the SMG reservoir relocation kit.

The main airbox section houses the six trumpets as well as the breather-system connectors. Made from prepreg carbon fibre, the airbox is designed to resonate under load and produce the distinctive CSL sound. One of the key engineering challenges was ensuring long-term reliability at the interface between the trumpets and the airbox. This was solved through the use of mechanical fasteners and gaskets, creating an airtight seal that remains unaffected by heat cycles and vibrations. A similar approach was used for the breather adapters.

The trumpets are manufactured from a glass-fibre-reinforced thermoplastic. The injection-moulding process ensures dimensional accuracy while providing smooth internal surfaces for optimal airflow. This method offers advantages over producing each trumpet in carbon fibre, as it guarantees consistent form with a precision unattainable through carbon construction. CNC-machined stainless-steel rings are also integrated into the trumpets to prevent deformation when the silicone couplers are tightened onto them.

The snorkel or lid of the airbox smoothly channels airflow from the intake to the trumpet area. This section also incorporates the MAF tube section where the OEM sensor is secured to a CNC machined MAF boss. The snorkel secures to the main airbox section using custom made screws which cut into plastic securing clips ensuring that they do not come loose under vibration.

The overall shape of the airbox was optimised over several iterations using CFD simulations to ensure the trumpets had adequate flow without suffering from starvation due to restrictions in geometry or turbulence.

The filter housing consists of Eventuri’s bespoke Generation 2 filter, a stainless-steel bracket, and the carbon-fibre housing. The carbon pod encloses the reverse-mounted filter and smoothly shapes the airflow toward the plenum. This is a key aspect of the intake design, as the tortuous flow path of the OEM airbox has been eliminated, reducing pressure loss throughout the system. This also ensures that airflow remains smooth as it enters the MAF tube section of the airbox, allowing the sensor to operate without errors.

Eventuri’s patented filter housings feature a smooth reduction in cross-sectional area as they shroud the filters and taper down toward the tubing. This geometry invokes the Venturi effect, accelerating airflow while maintaining laminar conditions. The design functions much like a large velocity stack—illustrated below in a diagram comparing the patented housing to a conventional intake system. Eventuri’s bespoke filters further support airflow through the housings, helping to maintain an even velocity profile as the air exits the system.

100% Prepreg carbon fibre with a CNC machined collar - the air scoop forces ambient air directly into the filter opening. This scoop simply clicks into place in the front right hand brake duct and effectively saturates the mouth of the intake with cold air. It has been designed to take up half the height of the duct in order to allow airflow to still continue through the duct for the brakes. The scoop is so effective that even after a hard drive, the aluminium cowl at the mouth of the intake will still feel cold to touch.

The Eventuri E46 M3 Hybrid Carbon Airbox is available in two configurations: with or without the Eventuri intake. The airbox-only option is offered to allow existing E46 M3 owners who already have an Eventuri intake to reuse their filter housing and scoop. The Hybrid Airbox system is comprised of a range of components, each engineered for a specific function and manufactured to the highest standards.