Black95GTS
Active Member
Well when you buy a piece of 4 inch PVC, that is the inside, or working diameter. The outside diameter is actually something like 4 5/8 inches. I just designed a bunch of PVC duct for a substation in New York so I am down with PVC!
Ideally, you'd want a perfectly straight tube that has no bends. A bend is a constant in terms of head flow reduction. You can go to the back of any fluids book and look up the table for a 90 degree elbow.
A change in pipe diameter size is different, in that the formula involves the radius squared, so its not a linear relationship. So the ideal intake would be something like a 75mm meter with a 75mm TB all using 75mm tubing. When you change the pipe size, you impact the pressure and velocity of the flow. Pressure and velocity are inversely related. The energy of the air charged is disturbed when one or the other is changed, which causes flow to be lost.
This is why I have a problem with the argument of sizing TB based on what the engine can flow. If engine X can only consume Y CFM flow, then some say get the TB that can feed that max flow. My opinion is to get a TB that can over flow that amount, because by the time the incoming air goes through the entire intake tract it will have lost some Z amount of head.
Sorry about the length.
Adam
Ideally, you'd want a perfectly straight tube that has no bends. A bend is a constant in terms of head flow reduction. You can go to the back of any fluids book and look up the table for a 90 degree elbow.
A change in pipe diameter size is different, in that the formula involves the radius squared, so its not a linear relationship. So the ideal intake would be something like a 75mm meter with a 75mm TB all using 75mm tubing. When you change the pipe size, you impact the pressure and velocity of the flow. Pressure and velocity are inversely related. The energy of the air charged is disturbed when one or the other is changed, which causes flow to be lost.
This is why I have a problem with the argument of sizing TB based on what the engine can flow. If engine X can only consume Y CFM flow, then some say get the TB that can feed that max flow. My opinion is to get a TB that can over flow that amount, because by the time the incoming air goes through the entire intake tract it will have lost some Z amount of head.
Sorry about the length.
Adam
