If you're not a mechanic, an engineer, or an automotive technology enthusiast, then chances are that many of the terms that salesmen throw around when describing the latest model on the showroom floor may be a mystery to you. Whatever dual overhead cams are, they must be better, and a car with a turbocharger must be faster than a car without one, right? Well, let's have a little vocabulary lesson to sort out some of this new car jargon.
Turbocharger
A turbocharged engine means that it has a small air compressor which effectively feeds air under increased pressure into the cylinders. When air is compressed it means that there is more air squeezed into a smaller space, so more air, and more importantly, more oxygen is fed into the cylinder during each cycle. More oxygen means that more fuel can be ignited with each stroke of the cylinder increasing the power output of the engine. The compressor is powered by the hot exhaust gases that come out of the cylinder after the combustion phase. These gases turn a compressor wheel without scavenging energy from the engine's output, making it a very efficient way to get more power out of an engine of a given size.
Dual Overhead Cams
Dual overhead cams or camshafts means that the intake and exhaust valves for the pistons are operated by rotating cams that push them closed and allow them to open instead of the older pushrods that were used previously. A single camshaft means that the cam operates only the intake valves. The dual overhead camshaft results in a smaller moving mass that can open and close the valves faster. This allows faster cycle time or higher engine speed, which, in turn, results in a higher power output than older model engines. Today, this is pretty much standard fare for internal combustion engines.
Cars which run only on electricity, on the other hand will have neither a turbocharger nor camshafts since there is no combustion (fuel ignition) taking place.