Boost guage tap location

[paul e]

This is a question that has many of us going nuts. .Somebody with a Dinan Vortech kit on his M3 found that tapping the brake booster line (which Dinan recommends) which feeds the bypass valve produces 2 to 3 psi HIGHER results than when tapping the Fuel Pressure Regulator (FPR) line under the car!

How is this possible, since they are both sourced from the intake manifold???

[///M3Ryder NY]

Where is yours tapped Paul?

[paul e]

chris, see the many threads on bf about this. I posted here for more info. IM tapped, like all dinan sc cars, in the bypss valve line, sourced from the brake booster vacuum line coming from the manifold. Its hard to understand why, in a closed system, where homeostasis is a property, two vacuum lines running from the same plenum/manifold source should report different results. I think the jury is out, although in one case, Croaks, he definitely measured +2 psi when coming from the brake boost line. Still, imagine if this were true, dinan guys reading 6 psi from that source would be expected to read only 4 psi from the fpr. if that were true, than its the fpr port Id suspect, not the brake boost one.