The exotic Porsche 918 Spyder uses a diffuser developed by MarchantCain.

Taking hydraulics and weight out of active aerodynamics

Hydraulics out, electric in, is the philosophy of automotive design and development specialist MarchantCain. The company, which developed the underbody diffuser for the hybrid 340-km/h (210-mph)—150 km/h (93 mph) using only electric power—Porsche 918 Spyder, is now also developing fresh active aerodynamic systems that Engineering Director Rob Marchant is confident they will potentially bridge the price, materials, and manufacturing gap between motorsport and low-volume exotic car applications to series production models, bringing weight savings that will help lower fuel consumption and CO2 emissions.

The new performance car innovations, designed and developed in the U.K., are what Marchant describes as “an advanced concept active aerodynamic system and a new active diffuser” system.

He adds: “Both are set to improve the performance of new vehicles and increase their fuel efficiency.” The products are based on electric actuators rather than hydraulic and utilize active aerodynamics to effectively add “mass” to a vehicle when required, while remaining lightweight and fuel efficient during normal operation.

“By removing the necessity of hydraulics, our new technology can save kilograms, dependent on which motive drive system was previously used in a car’s design,” said Marchant. “Hydraulic systems are too heavy and conflict with lightweighting. Performance hybrid vehicles are already struggling to overcome heavy battery weight so, while lightweighting is important for fuel consumption, it can lead to instability at speed. To prevent the car being moved by other aerodynamic loads such as cross winds, deployable systems that use active aerodynamics allow a vehicle to direct loads in the right proportion for the conditions. This maintains fuel efficiency and thus reduces emissions, so in effect you have the weight loss but you can also add weight when you need it, in the right place.”

The technology, aerodynamically tested by MarchantCain in partnership with Porsche and fitted to the new 918 Spyder, can be deployed by the driver to take account of various speeds and conditions. Marchant says this will help achieve minimum drag for lower fuel consumption, balance drag for downforce, and provide required very high driving stability at equally high speeds, as well as ensuring maximum downforce for optimum performance.

The material used for the Porsche application is carbon fiber, but Marchant suggests that a variety of advanced composite materials could be tested for possible use on higher volume production vehicles.

He explained the design process of the products: “The underbody diffuser was in development for two years and carried forward into production virtually unchanged. The other systems are currently in the prototyping stage and we are testing a number of materials to see which will provide the best lightweighting option. Once completed, these will go through similar aerodynamic testing to that applied to the diffuser for the Porsche 918. We already have a number of automotive OEMs following the development. The products are being carefully designed to enable them to cross into mainstream vehicle production in time as cars become lighter for fuel efficiency, and smaller engines continue to enhance overall vehicle performance.”

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