This question was raied by working on my brther' Dodge 2.2 turbo, but lingers in mind non-the-less and I thought maybe one of you bright guys out here would have an enlightne opinion. On his engie, the are four vacuum lines that all goto the same general area of the engine compartment. Why didn't Mopar run just one line, and then put a series of "t"s in the line. Would this approach have changed they way the vacuum signal would change, and thus hinder the reponse time of the device being regulated. AND, does the size of the vacuum line effect the way the signl reponds? I thought maybe a largeline would act somewhat as a vacuum resevoir and keep the signalfrom fluctuating enough. I also thought the multimple tubes was to keep the various devices from effecting each other. In the case of the 2.2 turbo, he lines in question o to a series of vacuum solenoids. These are switches that shut off or open the vacuum source to another accessory. For instance, one of them controls the turbo waste gate, and another controls the, EGR valve. Apparently the computer can over-ride thevacuum signal, and cut it off at times., suchas when the enine is cold for instance.

I do't know how prctical this topic seems, but sometimes theortical threads can lead to some interesting thought povoking discussion.

Appologies for the terrible spelling of the previous post. I have the terrible habit of typing faster than my keboard can register the letters, and I haven't figured out how to edit a post yet. Maybe you can't.

you can, but not as a "guest" you have to register and then you will see the edit button

I know that changing the diameter of the hose will change the vacuum signal. It is the same as water pressure. The volume of air flowing throw a skinnier hose will have more pressure/vacuum as the same volume flowing through a fat hose. Thats why you get a manifold vacuum signal drop when you install a four barrel carb as opposed to a one barrel.

I guess is all four of those hoses needed a strong vacuum signal (emissons components or feed to the vacuum doors in the dash etc...) then you would want to have four separate smaller lines as opposed to one big fat line. At least I think thats how it works...

Reed

Smaller lines, or one line teed to many, will damp the vacuum signal and respond more slowly than larger/more lines. Larger line = faster response. It is an issue of the power transmitted along the lines through the air/pressure stream.

Lou

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