Have you ever noticed that if you are a car enthusiast and you are buying a car, the first thing you would ask about that vehicle is its engine? Yes, we all do that. Because it’s the power of the engine that determines, How fast/ far/ long a vehicle can go? And when it comes to the engine of a performance car, it is really important to understand what is under the hood (bonnet)?
Koenigsegg, a Swedish automaker is known for developing extreme and timeless technology for hypercars. And its four-seater grand touring model Gemera is something that is years ahead in terms of technology and performance. Gemera is powered by a 3-electric motor and a 2L, 3-Cylinder (In-line) with Twin-Turbo internal combustion engine known as Tiny friendly Giant (TFG) by Koenigsegg with a net power output of 1700bhp with 0 to 100 Km acceleration of 1.9 sec. This 2L, Twin-Turbocharged, Tiny Friendly Giant can produce 600bhp with 600NM of torque. Its specific output is 300bhp per liter which is pretty much higher than any car on the market. More than twice of second most powerful In-Line 3 Cylinder Engine(Toyota GR Yaris, 257 bhp) till date.
Technology that makes TFG so powerful
Free or Camless valve Design
According to Koenigsegg, the TFG engine doesn’t use the conventional camshaft design for the opening and closing of the valve. Instead, this engine uses Koenigsegg’s cam-less technology developed by their sister company called Freevalve. A Camless or Freevalve technology has a poppet valve that operates by means of electromagnetic, hydraulic, or pneumatic actuators instead of conventional cams.
In a conventional camshaft engine, the timing of the opening and closing of the valve depends upon the path of the cam profile (which remains constant). As we can see in the animation below, the valve lift profile follows the cam profile, which is shown by a parabolic graph. But this is not the case in free valve technology, instead of relying on the restriction due to the nature of the mechanical camshaft, the desirable valve timing can be achieved by monitoring and controlling the lift and return (of valve) force are produced by the pneumatic system powered by an air compressor.
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| Difference between camshaft and free valve design |
Therefore allowing the opening and closing of each valve independently resulting more control over the lift, timing, and duration of the valve. This helps in the better flow of the air-fuel mixture at various speeds, which helps in reducing the excess fuel consumption by 15-20% compared to other similar engines. The elimination of movable parts such as the camshaft, timing belt/chain drive help in reducing the weight of the engine to just 70kg. Thanks to its independent valve control system, it helps in the cylinder deactivation when power demand is low resulting in better fuel efficiency of the engine.
Twin-Turbo Design
Another technology that makes TFG so powerful is its twin-turbo booster. Yes, a 3-cylinder engine with two turbochargers. But the turbocharger design in TFG is a little bit different. The design in TFG consists of each cylinder with two exhaust-valve (V1 and V2). Each exhaust valve is connected with an exhaust pipe. One exhaust pipe (V1) of each cylinder is connected to stage-1 Turbocharger. And, another exhaust pipe (V2) of each cylinder is connected to the stage-2 turbocharger which is shown in the animation below.
When the engine rpm is low, the free valve system will only activate the exhaust valve V1, allowing the exhaust gas to only flow towards the stage-1 turbocharger. This will concentrate all the exhaust pressure enough to spool the stage-1 turbocharger, producing 400Nm of engine torque at just 1700 rpm. And when the engine rpm increases, the free valve system will activate both the exhaust valve (V1 and V2), allowing the exhaust gas to flow towards both turbochargers. At the higher speed, there will be sufficient exhaust pressure to spool both stage-1 and stage-2 turbochargers producing a boost of 29psi to the engine and maximizing the engine torque to 600Nm at more than 2000 rpm.
