Magna’s New Active Airdam Boosts 2019 Ram Fuel Efficiency

March 1, 2018

Lindsay Brooke

2019 Ram 1500 shows active airdam deployed. The collaboration with Magna included development of validation requirements including bench testing.

For the all-new 2019 Ram 1500 pickup, FCA engineers again surprised their industry competitors with an impressive array of integrated technologies aimed at improving the pickup’s fuel efficiency. The list of segment ‘firsts’ includes 48-V hybridization, a heated/cooled rear drive axle and an active front airdam to optimize the truck’s aerodynamics.

Developed in collaboration with Magna International (which also designed the Ram’s active grille shutters), the new active airdam is designed to deploy at 35 mph (56 km/h) and retract at 15 mph (24 km/h). It is responsible for 40% of the new pickup’s total 9% aerodynamic improvement over the outgoing model, noted Mike Raymond, the Ram’s chief engineer.

“We got a few [aero] counts out of the new cab’s roof design and the taller tailgate, but the active airdam really brought us significant gains in both Cd and Cd(A), which is big for our highway fuel-economy numbers,” he told Automotive Engineering. Improving Ram’s Cd from 0.393 in 2018 to 0.357 in 2019 represents a 36-counts drag reduction—worth 1 mpg in highway operation, Raymond said.

Active aerodynamic systems qualify for the “off-cycle” credits that automakers can earn in their federal fleet fuel efficiency compliance. The current U.S. CAFE rules require average pickup truck economy to increase from 29.6 mpg in 2018 to 39.3 mpg by 2025.

System development began in 2014, after FCA’s DT program (2019 Ram) engineers had established some base geometries, including what the overall deployed height of the air dam should be. Then came some early wind-tunnel work.

“FCA came to us with a rough concept and we handed our Exteriors team ‘the reins’ to develop the product part,” explained Tony Povinelli, Magna’s Global Product Line Engineering Director. “The program included development of new test and validation requirements, including bench testing,” he added.

As a fullsize pickup, the new Ram offered adequate space between the front frame crossmember and the front lower fascia in which to package the airdam module. It’s a compact unit, consisting primarily of the airfoil and actuator assembly. Povinelli noted that the module’s control electronics communicate with the truck’s active grille-shutter system via LIN (Local Interconnect Network), the serial network protocol used for subsystems communication in the vehicle.

The composite airfoil is constructed using a ‘two-shot’ molding process using glass-filled nylon to create the blade’s spine, which then is overmolded with nylon/rubber ‘soft shot’ to provide a durable exterior.

The airdam’s actuator includes an electric motor, declutching mechanism and a controller. The system requires a 12-V power supply (48-V hybrid Ram trucks incorporate a DC-DC converter between their 48-V and 12-V networks). Magna’s Closures group developed the cam-type clutch mounted on the actuator output shaft, according to Povinelli. The clutch plays a vital role in ensuring that the deployed airdam can retract to avoid breaking if the underside of the truck’s front end impacts road debris.

“This is a very robust system,” Raymond asserted, “with the actuator designed for life-of-vehicle service.” He praised the Magna team as being “great to work with.”

With U.S. fullsize pickups and SUVs facing considerable regulatory pressure to increase overall fuel efficiency, Povinelli expects Magna’s active-airdam business to expand steadily, mirroring its 10 million active grille shutters currently on the road. The company is also developing active underbodies, active wheel deflectors and active rear diffusers, which can be applied across all passenger and commercial vehicles.