I just got a Greddy electronic boost gauge, and I'm a little puzzled about where and how to install the "T" for the boost sensor.

ScoobyMods.com had a thread on it (http://www.scoobymods.com/forums/showthread.php?threadid=562&highlight=greddy+boost+gauge), but it implied that the T-connector that comes with the gauge works fine in the recommended location (the hose coming off the fuel pressure regulator). However, the T that the gauge comes with looks like 3/16" all-round, whereas the hose coming off the fuel pressure regulator is 1/4". Obviously, then, to tap this connection you would need a 1/4"-1/4"-3/16" T, which doesn't seem to exist (at least not in auto parts or plumbing supply stores).

I guess the alternative is putting the T at the BOV, but I've heard this is a bad place to put a boost gauge.

Any ideas?

I would disagree that installing the T off the BOV is a bad idea. Vacuum is vacuum. Either location you mentioned should work fine.

I also found the T that came with my Greddy boost gauge to be too small. If you go to an Autozone or any auto parts store, you ought to be able to find a plastic universal T, which you can cut down until you get to your desired diameter. They usually cost about $2, maybe even less.

Joel

yah, i put the T on my bov line and it is working absolutely fine. :D i have a utec and compared the lamco (sp?) boost guage with it and it's very accurate (or both off identically. :lol:)

Originally posted by Zola Rex
I also found the T that came with my Greddy boost gauge to be too small. If you go to an Autozone or any auto parts store, you ought to be able to find a plastic universal T, which you can cut down until you get to your desired diameter. They usually cost about $2, maybe even less.

Joel

Exactly. My "T" fitting (actually looks more like a "Y") that I got with my Omori gauge was too small as well. My local Subaru dealer was able to hook me up with a "T" fitting they use for the stock boost gauge installs. Maybe you can ask your local dealer/svc tech?

btw, I mentioned the similar problem with my Omori fitting because apparently GReddy is made by Omori. The only difference in the "Y" fittings is that GReddy stamps their name on theirs.

Kean

I originally installed the "T" by the fuel pressure regulator, but never saw vacuum and the boost only hit any sort of value around 6,000RPM (I'm guessing this was a totally wrong location, but it was the one pictured on either Scoobymods or Ravensblade). I now have it off the factory BOV and it works great... and has for almost a year now.

put it by the bov. that is hte best location according to subaru.

Ok, I got my gauge installed . . .but I've noticed that I almost never see vacuum. The gauge sits at zero pretty much anytime I'm off the throttle, and peaks at about 0.5 kg/cm^2 (7.1 psi).

I wish I had a picture to make this more clear, but I just want to make sure that I am actually referring to the correct parts.

The factory boost gauge install manual shows the hookup for the gauge coming off the fuel pressure regulator (which is in front of the intercooler, correct?). This is the one I was talking about earlier, with the 1/4" hose.

I tapped off what I think is the BOV (to your left, near the passenger side shock tower as you look at the engine from the front?). There were two sections of 3/16" or 1/8" hose joined by a plastic coupler; that's where I inserted the Greddy "T".

So, in short, are the fuel pressure regulator and the BOV different, and if so, which is where?

EDIT: Doh! I'm a noob . . . the BOV is in front of the intercooler . . .so what the hell did I just splice off of? (The brass-coloured thingy above the turbo next to the passenger-side shock tower)

Originally posted by banman
Ok, I got my gauge installed . . .but I've noticed that I almost never see vacuum. The gauge sits at zero pretty much anytime I'm off the throttle, and peaks at about 0.5 kg/cm^2 (7.1 psi).

I wish I had a picture to make this more clear, but I just want to make sure that I am actually referring to the correct parts.

The factory boost gauge install manual shows the hookup for the gauge coming off the fuel pressure regulator (which is in front of the intercooler, correct?). This is the one I was talking about earlier, with the 1/4" hose.

I tapped off what I think is the BOV (to your left, near the passenger side shock tower as you look at the engine from the front?). There were two sections of 3/16" or 1/8" hose joined by a plastic coupler; that's where I inserted the Greddy "T".

So, in short, are the fuel pressure regulator and the BOV different, and if so, which is where?

The factory BOV (or bypass valve I guess) is the one in front of the intercooler on the driver's side. Here's a pic of it I found on scoobymods.com:

http://www.scoobymods.com/forums/attachment.php?postid=4854

Kean

EDIT: oooops. Just noticed your correction. Well...anyhow...there's a pic if anyone was a bit confused.

You tapped off the wastegate, not the BOV. That is the reason your gauge isn't working properly, the wastegate doesn't get direct manifold vacuum. It's "filtered" by restrictors and the boost control solenoid.
The BOV (actually bypass valve) is the one bolted to the front of the intercooler. The hose going to that valve is the one you want to tap, it is connected to the manifold. Once you move your gauge connection to there it will work the way it's supposed to.
The fuel pressure regulator is located at the front passenger side of the engine and has a very short vacuum hose to the manifold. This is technically an acceptable place to tap as well, however due to the location and the hose being very small and short it is not as ideal as the BOV.

I tapped my Defi BF boost guage into a line on the left of the manifold, opposite the BOV. I get consistent readings at exactly 1 bar and the lines sizes were similar to the Defi tubing, e.g. very easy to hook-up.