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1slow370 · 09-23-2014, 02:45 PM

hmm kind of touching on it but kind of not, a velocity stack prevents boundary layer separation which basically reduces restriction at an air (or fluid) inlet, they do not aid in the tunning of an intake manifold but are merely a feature that stabilizes the incoming airflow, the manifold is tuned by adjusting the length, taper, and diameter of the runners(longer velocity stacks are just runner extensions with the same entry profile as a shorter one. The reason that Velocity stacks loose effectiveness in a longer intake system is that they are no longer the primary restriction, the tube wall friction, bends, and pressure loss is.

The other thing to take note is that not all velocity stacks are created equal, I can't remember the name of the text but there was a good book on air velocity that described the differences between the airs density and velocity and the path a of the boundary layer for a tube inlet (a velocity stack is basically designed to follow the path of the air closest to the tube that wants to bend and enter it.

09-23-2014, 02:45 PM	#73 (permalink)
1slow370 A True Z Fanatic Join Date: Aug 2009 Location: In the D Posts: 3,732 Drives: v8 74 260z ;) Rep Power: 7251	hmm kind of touching on it but kind of not, a velocity stack prevents boundary layer separation which basically reduces restriction at an air (or fluid) inlet, they do not aid in the tunning of an intake manifold but are merely a feature that stabilizes the incoming airflow, the manifold is tuned by adjusting the length, taper, and diameter of the runners(longer velocity stacks are just runner extensions with the same entry profile as a shorter one. The reason that Velocity stacks loose effectiveness in a longer intake system is that they are no longer the primary restriction, the tube wall friction, bends, and pressure loss is. The other thing to take note is that not all velocity stacks are created equal, I can't remember the name of the text but there was a good book on air velocity that described the differences between the airs density and velocity and the path a of the boundary layer for a tube inlet (a velocity stack is basically designed to follow the path of the air closest to the tube that wants to bend and enter it. __________________ ANSWER PRICE LIST Answers - - - - - - - - - - - - - - - - $0.75 Answers (requiring thought) - - - - $1.25 Answers (correct) - - - - - - - - - - $12.50 Last edited by 1slow370; 09-23-2014 at 02:53 PM.