Rez

I've been researching vacuum hose size and lengths lately. From what I can tell, PET shows the ID of the small hoses (vacuum advance/retard) to be 2.6mm and the PET specifies vacuum hose length. Since I have length and ID and can calculate volume of air inside the hose. I recently purchased 3.2mm ID from Hose Techniques, and I realized that its volume will be slightly higher.

Should I compensate by reducing the 3.2mm hoses length to make the volumes the same, or am I missing the whole point and it doesn't matter?

Sean79 5spd

I suspect it doesn't matter. I used the closest Hose Teqhniques sizes on my 79 with no problem. I also doubt very much if I cut the new hoses to exactly the same length as the origuinals.

SharkSkin

Doesn't matter. Not on this size hose. PorKen reported an improvement in throttle response by dramatically reducing the volume of his system of intake hoses, but the difference you are talking about is insignificant.

jpitman2

The hose volume will be swamped by the volume of the vacuum tank in the cruise control, or one feeding the heater controls. If you try to pump vacuum with a mightyvac with this tank in circuit, it will be very slow to come down.
jp 83 Euro S AT 47k, BTDT

SharkSkin

jp, I think the reservoirs you refer to are on a completely separate circuit, and with their check valves they only figure into the equation at max vacuum anyway...