What is the working principle of engine supercharging?
4 Answers
The working principle of engine supercharging is: by increasing the air pressure in the intake manifold, overcoming the interference resistance of the valves, and increasing the fuel injection volume, the engine's working energy is enhanced. Mechanical supercharging mainly relies on belt drive, and the speed of the internal blades is completely synchronized with the engine speed. The output of a mechanically supercharged engine increases with the rise in engine speed. Engine supercharging refers to addressing the issue of low intake efficiency in naturally aspirated engines at high-speed ranges. It can be divided into: 1. Centrifugal supercharger; 2. Roots-type supercharger; 3. Screw-type supercharger.
Last time I helped my buddy modify his old V8 muscle car, I researched this. Simply put, a supercharger is essentially a blower directly driven by the engine crankshaft that forces air into the cylinders. When the engine runs, the belt spins those two big helical rotors inside the supercharger like crazy, compressing the air denser and denser. More oxygen molecules mean you can inject more fuel. Unlike turbos that wait for exhaust gases to spool up, superchargers deliver instant throttle response and that kick-in-the-back feeling. But the downside is obvious—it saps engine power to drive the blower, so fuel consumption goes up. When modifying, remember to upgrade to forged pistons; stock ones can't handle the high pressure. The tuning shop told me that the distinctive whine of a Roots-type supercharger comes from the rotors chewing through air—totally badass.
Anyone who's driven a supercharged car knows the instant kick-in-the-pants acceleration when you floor it feels completely different from naturally aspirated engines. The core mechanism uses a belt to connect the supercharger to the engine - as soon as the crankshaft turns, it drives the supercharger rotors in sync. The most common type is the twin-screw design, where two metal rods with helical grooves mesh together, forcibly compressing air from the intake to the outlet. The new Mercedes-AMG C63 uses exactly this technology. During actual driving, I noticed an interesting phenomenon: superchargers perform more noticeably in winter when temperatures drop, because cold air is denser. But beware of heat soak during prolonged high-load operation - adding an intercooler makes a big difference.
Old-school drivers might remember that superchargers were already used in racing cars back in the 1930s. Nowadays, there are three main types: Roots-type, twin-screw, and centrifugal. The Roots-type works like two butter knives scraping against each other, sucking in air at the low-pressure zone and squeezing it out at the high-pressure zone. The twin-screw is similar to twisting a rope, getting tighter as it goes. The centrifugal type is like a small turbo but driven by a belt. The most impressive thing is that superchargers can adjust the boost ratio on the fly. Porsche's VTS system, for example, intelligently controls the supercharger coupler based on throttle input. A mechanic at a tuning shop once taught me a trick: if you hear the supercharger making a high-pitched whine, check it immediately—it usually means the rotor bearings are about to fail.
