If you're drawing 15 inches of vacuum through a line that is 5/16" in diameter and 2 ft in length and you change the line diameter to 1/8" that is 4 ft in length, does that affect anything?

Seems to me the smaller diameter would be more restrictive, thus changing the dynamics of the system, or is my logic misplaced?

 

Depends on the load, but, overall, it would pull vacuum to steady state condition more slowly in the second example. If it were filling a vacuum can, you might not notice a difference, all depending on how often that can is tapped.

 

If you are talking about your trans vacuum modulator line, there is no difference in functionality. At some point the combination of length and diameter may induce temporary differences in the pressure level from one end to another, but that is a transitory event. The reaction time of the modulator won't be affected by it.

 

You’re correct when it’s flow rate, but the distal end of the hose is blocked so there’s no air flow after the initial vacuum application.

 

So I've noticed...drove it to work today and all good. Thanks Joe.