skssgn wrote:
I'm pretty curious about this setup - so there is a vacuum line from the manifold to a reservoir tank, then the tank to the booster. What does the tank do? are there any non-return valves or anything? are the main pipes rubber or metal? I wonder if there is a drop in vacuum caused by rubber lines sucking in under pressure or something... it'd be interesting to attach a vacuum guage at the manifold and at the booster to see if there is a difference, or if that amount of vacuum line (which should constitute part of the induction length, shouldn't it??). Ever tried blocking it off at the manifold and seeing if it runs differently?
exactly the same concept as a pressure accumulator in a hydraulic or compressed air system, except in reverse! If the engine stalls there is enough vacuum (lack of pressure) to apply the brakes 3 or 4 times before it becomes unboosted (yet to test this). Normal boosters if the engine stalls you get one application before the vacuum disappears. I think it also helps the 850 maintain the vacuum over the long distance to the booster, because it does not pump nearly as much air through the engine as a 1275
michael
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