Naturally aspirated engine
A naturally aspirated engine is an internal combustion engine in which the air does not in addition by a compressor or a turbo-charger ( charging engine, supercharged engine ) is precompressed. Small internal combustion engines are often naturally aspirated, but the trend is here to charge, as this is more efficient. For some sports car naturally aspirated engines are aware, since these have no turbo lag.
In four-stroke engines is one of the four strokes of the intake stroke. The mixture is doing ( now rarely ) sucked through an injection or a carburetor through the open intake valve in the cylinder head to the cylinder, since the movement of the piston creates a low pressure in the direction of the crankshaft.
For two-stroke engines, the mixture is first sucked into the crankcase, while the piston away from the crankshaft. Only when the piston is moving again to the crank shaft out by pressing the mixture into the cylinder transfer ducts.
Advantages and disadvantages (compared to a same engine with supercharging )
- Easier Maintenance
- Lower production and development costs
- Higher reliability because fewer items
- Immediate throttle response (no turbo lag )
- Reduced efficiency
- Worse power to weight ratio
In a naturally aspirated engine, the actual engine noise (the individual ignitions) to be heard clearly. In turbocharged engines a part of the ignition noise in the exhaust turbine is lost. Instead, be heard when the load changes, the hiss of the blow-off valve.