Well, the application there seems to be a small-turbo engine trying to rev to the moon, so I guess I will never see a STIC engine,lol. I mean how could an NA engine ever build that much backpressure in the exhaust to where it stifled the intake.
It's not a turbo engine just a single cylinder MX bike. I thought the same thing about the backpressure.
He posted up this in response to someone's question...
Perhaps you have observed engines that are on an engine dyno with the air box off; you will note at certain times it appears that two things are happening at the same time. [1]: You will notice that there is a large plume of fuel vapor exiting the carburetor/fuel injection at the same time the engine is running. [2]: In the real world in the intake process; there are two or three things happening in both directions at the same time. During the intake process, there are sonic shocks waves traveling back and forth in the intake system at the speed of sound [approximately 750 mph] see Wikipedia:
Wikipedia: “A sound waveas it propagates through an elasticmedium. In dry airat 20 °C (68 °F), the speed of sound is 343.2 meters per second (1,126 ft. / s; 1,236 km/h; 768 mph; 667 km).”
Here is what happens; as the engine vacuum [suction] decreases under hard acceleration; there is a proportional increase in positive back pressure and this combined with the sonic pressure waves allow two things to happen at one time. Thus you will have an induction into the engine in an area of the carburetor bore, and at the same time, you may see a process called double fueling wherein a portion of the intake air/fuel mixture is traveling backward in another area of the carburetor away from the engine.
