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Oorspronkelijk gepost door: MTX-speed
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Geluid is niets anders dan drukgolven van een gas. Je trommelvlies zet deze drukgolven namelijk om in geluid wat weer via een elektrische stroom naar je hersenen gaat.
Door de resonantie van de drukgolven van de uitlaatgassen die zich in de expansiepijp bevinden ontstaan deze vaccuumgolven.

De stromingsleer die wordt toegepast is overigens niet simpel, dus zeker niet zomaar ineens te begrijpen.

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Oorspronkelijk gepost door: MTX-speed
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Wat betreft die extra uitlaatklep:
Ik heb zelf bij mijn Honda MTX200R de werking van het complete ATAC-systeem eens nageplozen. En inderdaad, beneden de 5500rpm ging de klep open en boven de 6000rpm ging de klep terug dicht. In de cilinder zat een loze ruimte die geopend wordt waardoor de totale expansieruimte wordt vergroot. Omdat de voor een goede resonantie op laag toerental een grotere expansieruimte nodig is, wordt deze ruimte dus ter beschikking gesteld. Je kunt dit ook heel goed zien in de koppel/toeren-kromme die te zien is op een vermogensuitdraai.

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Some power valve systems simply restrict the exhaust gases after they have exited the combustion chamber, while others (such as Suzuki AETC) have valves that actually protrude to almost as if they are in the combustion chamber. The AETC system replicates the size and shape of a cylinder with small ports when they are closed giving good low rpm power, and when open replicate an engine with large exhaust port(s) to give good high RPM power. Yet another system opens and closes a sealed cavity in the head; V-TACS uses this system. On the most basic level, the power valve system simply varies the size of the exhaust port, allowing a small port to be used at low RPM's, and a larger port at a higher RPM. On a more complex level, however, many power valve systems change the compression ratio as well, allowing the optimum compression for low and high RPM's.

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The "V-TACS system" works differently from the "AETC system" and it will only work when it is used in conjunction with a tuned muffler. Tuned mufflers/expansion chambers increase power but only at the RPM they are designed for and can actually cause a power loss outside their tuned RPM. "V-TACS system" takes advantage of using an expansion chamber without losing power outside the expansion chamber's tuned RPM. Within the head and cylinder of the engine, there is a chamber that is sealed by a valve. This sealed chamber is vented onto the exhaust port when the valve is open. At low RPM this valve is open, this has the effect of increasing the exhaust manifold volume and negating the power loss that would normally be apparent at low RPM with an expansion chamber. At mid RPM the valve is closed, this enables the expansion chamber to work. It is identified by the head and cylinder, being much larger than normal for its displacement, the cylinder is also cast with the wording VTACS on it.

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