Port velocity

JstasJstas Posts: 14,222
edited May 2008 in Car Subwoofer Talk
How fast do you think you can go before it causes problems for being too fast?

Reason is I have two boxes designed. One has a port velocity just about 48 m/s the other design has a velocity up neat 70 some odd m/s.

Question is how fast can you go before the port becomes inefficient?

The way I understand it is that the port velocity adds some major oomph to the pressurization of the cabin the faster it is. The problem is though that the air can only move so fast before it starts tumbling over itself. In other words, the aerodynamics of the port walls will slow the air flow down and you get uneven pressure. I know there is a point where you hit that but I don't remember what that point is.
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Post edited by Jstas on


  • FaceFace Posts: 14,714
    edited May 2008
    Are you using WinISD?

    It will tell you if your PV is too high.
    "He who fights with monsters should look to it that he himself does not become a monster. And when you gaze long into an abyss the abyss also gazes into you." Friedrich Nietzsche
  • JstasJstas Posts: 14,222
    edited May 2008
    WinISD is at home. I'm bored at work. Doing the math by hand.

    Port velocity shouldn't be more than 24 m/s. I found it on another forum. I have about 25.1 in a revised box design but my ports are flared at both ends so the extra velocity shouldn't be an issue. Besides, it's within the 2% error rate anyway. I think it will be fine.

    Also, I noticed that carstereo.com's calculators are a bit generous.
    Expert Moron Extraordinaire

    You're just jealous 'cause the voices don't talk to you!
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