first things first, why do all of this?
PVC system makes me angry.
N249 makes me angry.
well, this is a guide to improve on your car's vacumn system to give you, faster boost response, better spoolup between shifts, cleaner blow off (FLUTTER
) and more accurate and consistant boost control. well, that's the plan at least. some people may say this is crazy talk, and i'm always open to criticism.
what will you need? some vacumn hosing, some T's, hose clamps, a check valve, MBC and small hands. (this isn't a step by step how-to guide, this just shows you what needs to be changed and with what, not how..)
oh and you do this at your own risk. i can't babysit every struggler.
first things first.
here is the stock system:
here is a simple version of the specific areas we are working with:
ok, see the red circle towards the bottom.
that vacumn line runs to your PCV (the big 3-way unit if you follow the line right and down)
you need to install the check valve there so that air can flow towards the intake manifold. this basically keeps more boost retained in your system as air can't flow out of your intake manifold there. (the pcv is suppose to prevent that, but typically does a crappy job of it). score. that was easy enough..
now, in the same area (red circle) .. between the check valve and the intake manifold (inline on the hose) install a T. this is where you will now tap for the BOV/DV. this is much more accurate and will better tell the BOV what is happening relative to your intake manifold. normally the N249 controls this..
see the blue circles? one is a vacumn box on top of your engine, simply cut that bastard off, pop a screw in the hole in the hose and clamp it off.. next, pull the host off your BOV/DV and clamp that sucker off as well (2nd blue circle)
ok, N249 functions, it's plugged in, but it doesn't do anything anymore. you will probably throw a code for this from now on, no cel, just a fault code.
now that T you did earlier, run enough hose from it so it can reach your BOV/DV. now these directions assume you are going to run an MBC with this setup as well.. put a T at the end of that hose, and connect a hose from the T to the top of your DV/BOV. now your bov/dv sees exactly when vacumn is created in the intake manifold. joy!
ok
the mbc/n75.. normally it pulls boost off the charge pipe (orange circle). well, that's stupid, because your real boost is in the intake manifold. so put another hose on the other end of that T you just made from the BOV and connect it to your MBC/N75.
now you have a hole in your charge pipe. well, either cork it or put it to use.. if you have a Greddy Type S, hook that hose up to the bottom line of the BOV.
this shows the valve when pressure is in the charge pipe relative to the top of the valve which shows when vacumn is in the intake manifold. this allows a cleaner blow off, faster response and *hopefully* no more low boost flutter.
almost done.
ok, see the MBC, you just hooked that sucker up, you can either route it directly into the system (black arrows -> wastegate) or put it inline with the N75 (brown arrow exception -> N75)
why a MBC and an N75? don't they do the same thing?
sorta...
N75 bleeds off air to regulate pressure.. that means your wastegate opens prematurely. put an MBC inline to the N75 (brown arrow) and set it to the same boost levels roughly and you'll get smooth linear boost, this = faster spoolup. (makes a huge difference on my T3/T04E)
ok, thats pretty much it.
if you want to be a super star, you can also put in a checkvalve like this...
that will allow your wastegate to instantly shut between shifts, your bov should now be able to handle that type of pressure change, so expect less boost loss between shifts, wheee!!!
again, do this all at YOUR own risk. i am not responsible if you suck and mess your car up.
if you don't think this is the vacumn system "done right" what would you change?
VWvortex
link for conversation on this.
All Information was provided by nrml on VWvortex...
