Ideal Vaccuum hose..

[Blitzeclips]

Would anyone care to comment on the ideal/most efficient diameter for vaccuum lines? I'm using a 6mm for the FMU and I get some hesitation when I stomp it. I was thinking of switching to a 8mm, but don't know if bigger is better in this situation.

Thanks for the help.

 

[VelocitàPaola]

Meh?

I think I used 3.5mm hose for the boost gauge, wastegate, FMU, and FPR. I only used 6mm for the P-port to EVAP line, and 10mm for the PVC valve. I'd think whatever you're using now is fine. As long as the vacuum line diameter isn't significantly smaller than the fittings on whatever you're connecting it to, you should be fine.

With regards to vacuum operated peripherals, such as FMUs, wastegates, etc., pressure is the variable we're primarily concerned with, not flow rate.

Pascal's law: "A change in the pressure applied to an enclosed incompressible fluid is transmitted undiminished to every portion of the fluid to the walls of its container." Thus, a change in pressure in the vacuum system should equally affect each component connected. Vacuum line diameter will only affect flow rate, not static pressure.

Now, this isn't to say that you can use 25 micron diameter tubing or something... at that scale, flow rate will have an effect, as air, the working fluid, can't flow quickly enough through the system to equalize the pressure. Pascal's law still applies, but the effect is delayed. At larger scales, however, this phenomenon should be negligible.