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GM is one of the keen customers of supercharger. Most of its mid / full size saloons, such as the Pontiac Grand Prix GPX shown in here, have a 3.8 litres supercharged V6 as an option. |
Before Turbocharging arrived in the 60s, supercharging used to dominate the forced induction world. Supercharging, also called mechanical charging, appeared in around early 20s in Grand Prix racing cars in order to increase power. Since the compressor is driven directly by the engine crankshaft, it has the advantage of instant response (no lag). But the charger itself is rather heavy and energy inefficient, thus cannot produce as much power as turbocharger. Especially at high revs, it generates a lot of friction and thus energy loss and prevents the engine from revving high.
A typical supercharger transforms the engine - very torquey at low and mid range rpm, but red line and peak power can appear much earlier. That means the engine becomes lazy to rev, but at any time you have a lot of torque to access, without needing to change gears frequently. For these reasons, supercharging is quite well suited to nowadays heavy saloons, especially those mated with automatic transmission.
The noise, friction and vibration generated by supercharger are the main reasons prevent it from using in highly refined luxurious cars. Although Mercedes-Benz has introduced a couple of supercharged four into the C-class, they are regarded as too unrefined compared with the V6 serving other versions.
The introduction of light-pressure turbochargers also threaten the survival of supercharger. The Volkswagen group, for example, dropped its long-standing G-supercharger and chose a light-pressure turbo.
| Advantage: | Torquey and relatively cheap, no lag |
| Disadvantage: | Lack of top end power boost, ruins revability, unrefined noise and vibration. |
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