BigBadWhitey

iTrader: (3)

Im running an LT1 with a procharger D1, pullied for around 5psi at 5500 rpm. To monitor pressure I'm running an AEM digital boost gauge, max 30psi display.

My problem is this - The gauge will show vacuum, but when I lay into it the best I get out of it is 0 boost/vacuum, it never begins to climb past that. With this setup, when should I be seeing boost? Some people are telling me I wont see any until I.m close to 5k rpm due to the pulley setup, and others saying i should see it start to climb as soon as I hit the throttle.

Now this may seem retarded, but should I be able to "manually" check the gauge, say by blowing into the hose? If i suck through the hose, i can get it to show vacuum, but no pressure.

The hose is attached to a T fitting off the intake manifold, shared with the bov, with no check valve in line with it.

Suggestions/criticism/anything strongly appreciated.

Sweet_SS

I am not familiar with SC setups, but you need to check for boost leaks. Sounds like that is your issue. Also, the BOV should have its own supply of vacuum...don't share. I agree with the others, boost should start to climb as soon as you hit the throttle.

vmapper

iTrader: (8)

Make sure your bypass (or correctly hooked up BOV) valve is closing

Are you noticing the boost?
Are you able to log?
You would see some amount of boost at WOT at most rpm range. Im guessing a D-1SC? would definitely see something even at 3000.

1BADAZZSS

iTrader: (23)

Hook a blow gun to a air compressor and blow air into the hose for the gauge. If it doesn't show boost then its the gauge.

BigBadWhitey

iTrader: (3)

SweetSS - I believe on the manifold I only have 1 spare vacuum port, one goes to the brake booster, and one goes to....I cant remember. If i had a vacuum manifold off of the one spare one, wouldnt that be the same as having a T fitting, or would that be a better option?

vmapper - The BOV is fully closed when its off of the car, seems to be making a complete seal. When the car is running, its fully open. When I give the car throttle while driving the car no longer sounds like its letting air out through the BOV and when i push the clutch in to shift I hear the loud "whoosh" of air being released, so I assume its working correctly? Any other way to test?
As for noticing boost, I dont have much to compare it to so im not 100% sure what id be feeling for. I am running the stock computer and can log with TTS datamaster.
Its a D1 (non self contained, so it should have a higher step up ratio than a D1SC)

1BADAZZSS - Thank you, I will try that

Bob@BruteSpeed

iTrader: (16)

I would think your boost gauge is not working, as you hear the boost being relieved. Bob

WheelsUp84z

iTrader: (14)

bad guage or bad sending unit if its an electronic guage

BigBadWhitey

iTrader: (3)

Update - I hooked my air compressor up the the boost gauge and was able to verify that it would read pressurized air, from 30 all the way down to 1 psi.

So is my next step searching for boost leaks? Is there any good way to do this?
Can i take the vacuum hose off the BOV, therefor closing the valve, start the car and see if its running on less vacuum at idle, or am i just asking for trouble with that.

Im really at a loss for ideas.

Bob@BruteSpeed

iTrader: (16)

Take the intercooler tubing off at the throttle body and at the blower and cap both ends. Drill and tap one end for a schrader valve so you can add air pressure to it. Bob

Cam72aro

iTrader: (28)

If its only pullied for 5psi at 5500 rpm's then your boost will be linear up to that. At 4000rpms you might only be making 2 or 3psi, then on up. Also make sure you have the correct rotation head unit its happened many times on here.

BigBadWhitey

iTrader: (3)

Rotation is correct, so it seems. Or else it would be sucking air, right?

Hmm maybe then it is just pullied really low.

Bob@BruteSpeed

iTrader: (16)

If the rotation is wrong it won't be sucking air. Running the blower without the outlet tubing connected should produce a very healthy amount of air, if the rotation is correct. Bob

BigBadWhitey

iTrader: (3)

It does, i managed to sweep my street with it when it blew a charge pipe off.

So i just watched this video:
And his boost seems to ramp in right at 2k rpm? And hes only making 7psi.

With that said, even at 5psi shouldnt i come into boost by 3-4k? Im at a loss here as to what is wrong with it.

Bob@BruteSpeed

iTrader: (16)

Yes, you should start seeing boost much sooner. Perhaps your bypass valve is sticking or hanging up. Bob

BigBadWhitey

iTrader: (3)

Ok so i took it out for a run the other day, and this time rather than rolling into it i just floor'd it, and at around 3.5k I saw 2 psi. So now it sees boost!

Not that i really understand why, but ill take it.

Bob@BruteSpeed

iTrader: (16)

Sounds like your bypass valve may be sticking. Bob