You can’t fight physics. The engine is typically the heaviest component in a car, and when you’re making a sharp curve, it doesn’t necessarily want to follow, which can affect handling.
What makes it worse is that most engines are mounted on relatively flexible bushings, which automakers use to help keep engine vibration from entering the cabin. Porsche tackles the problem with its new Active Drivetrain Mount, standard equipment on the 911 Turbo, which combines the best qualities of flexible and solid engine mounts.
When you turn a corner, your car follows the steering position, but inertia causes the heavy engine to initially keep going in a straight line. It continues to do this until the flexible mounts reach the end of their elasticity.
This causes instability, and in extreme cases on a rear-engined car such as the 911 Turbo, could potentially result in oversteer, a dangerous situation in which the back end of the car swings around and the car spins. A solid, inflexible mount keeps the engine in line with the car’s direction, but with a stiffer, noisier ride.
“What these active mounts enable the car to do is to stiffen up the connection between the drivetrain and the body of the car when you’re driving aggressively, and then soften it when you’re not,” says Laurance Yap, public relations manager for Porsche Cars Canada.
The mounts use a magnetically-activated fluid and an electrically-induced magnetic field that affects the fluid to a higher or lower degree. This changes the fluid’s viscosity, making the engine mounts harder or softer.
The system was originally designed for suspension components, but Porsche’s application is a first for engine mounts.
Under normal driving conditions, such as highway cruising, the fluid is “looser,” which helps absorb vibration. When the system is in sport mode, the car uses a variety of parameters to determine fluid stiffness, for a more direct connection between engine and body.