riff_raff wrote:Acoustic energy is put to good use increasing power in F1 engines, through the use of acoustically tuned intake and exhaust pipe lengths. The noise your ears "perceive" from an F1 engine is due to the frequency and amplitude of the exhaust pressure pulses emanating from the exhaust pipe exit point, propagating through a dense fluid atmosphere, and striking your eardrum membrane causing it to vibrate.
This acoustic energy is most definitely energy lost from the engine. The "loudness" of the noise is generally a function of the blowdown energy going down the exhaust pipe. And for F1 engines with very early exhaust valve opening events, the initial blowdown pressure can be quite high.
But, as others have noted, it's all about how noise is perceived. Check out Lotus' active noise cancellation technology:
http://www.grouplotus.com/managedcontent/view/44
however, we can do all of them by computer today.
