As advanced as internal combustion piston engines have become over the past few decades, they’re still hampered by a few basic design limitations. Chief among these is the camshaft, which opens and closes the intake and exhaust valves via a mechanical linkage.
In the days before variable valve timing, changing camshafts to gain performance was common. Increasing the lift (opening of the valve) and duration (length of time the valve was opened) would increase power, but at the expense of a lumpy idle and increased emissions.
Today, variable cam profiles help to provide more power and lower emissions while maintaining driveability, but one Swedish company, Cargine Engineering AB, thinks it has a better solution. This week's episode of Inside Koenigsegg takes a look at a new way of opening and closing engine valves.
Cargine’s Free Valve system relies on pneumatic valve actuators to open valves, which are then closed by air pressure or springs. The design eliminates the need for a camshaft, which can reduce both engine size and weight.
Since each valve can be controlled individually, more precise operation is possible, resulting in both significant gains in output (up to a 30 percent increase in horsepower and torque) and a jump in fuel economy (also up to 30 percent). Overall emissions are reduced by a claimed 50 percent, too.
The Cargine system replaces mechanical valvetrain components, allowing significantly higher engine speeds. With small valves, like those typically found in motorcycle engines, engine speeds of up to 20,000 rpm are possible. The Cargine valve actuators can work with larger and heavier valves, too, but at lower engine speeds.
The Cargine Free Valve system is currently undergoing durability testing, and a modified (and cam-less) Saab 9-5 has been running with pneumatic-operated valves for over two years and 60,000 kilometers (37,200 miles).
There are still bugs to be worked out, but Christian von Koenigsegg believes that the Cargine system represents the future of the internal combustion engine. Ideally, it will come to market in another three to four years, and you can expect to see the production-ready version beneath the hood of a future Koenigsegg model.