PCV feasible boost source for MAP?

[Spoolin98]

Im looking to switch over to SD and Im running out of boost sources on the 1g intake manifold.
Im already T'd off the BOV for my MBC, which I know is not preferred.
And Im T'd off the FPR for my boost gauge. I dont want to T off anything else for manifold pressure for the MAP.
I know that I could pull the manifold off and drill and tap it for boost sources but Im trying to do this without removing the IM if possible.

There is a galley on the 1g manifold that is right above the EGR and it runs the entire width of the manifold. There are plugs on either end of the galley.
I removed the plug above the EGR and installed a barb fitting for a boost/vacuum source. Im just not sure if this is going to work and wanted to see if anyone else has done this?

The picture of the runners shows how the galley gets the pressure, there are tiny holes in each runner. This galley feeds the PCV valve boost and vacuum but it looks like its designed to minimize boost and maximize vacuum. Otherwise I think Mitsubishi would have fed the PCV the same way they fed the BOV and FPR right off the main plenum.

What do you guys think? Can I use this as a boost source for my MAP?

Oh and the pictures are of a spare intake manifold I had laying around.

 

[007jimmy]

I could see this working but the MAP would get coated with oil from the PCV and soot from the EGR. Now if the EGR is blocked and you have a good internal baffled catch can to stop the PCV oil in theory that port should work as a air pressure source.

 

[Spoolin98]

The EGR is blocked off and the galley isnt connected to the EGR passages.
From my experience oil doesnt really back up into the manifold unless you delete the baffles in the valve cover and suck in oil under vacuum. All my baffles are in place and I have a check valve in the PCV line.

 

[007jimmy]

Ok nvrmnd the EGR its blocked. I rememberd when i pulled my intake it had a coating of sludge like stuff in the runners. When you pulled the side plug on your intake was that galley clean? Maybe shine a light in there right quick. I just didnt want see the MAP get that same sludge. But like i said it should work.

 

[Spoolin98]

The oil in the manifold was probably due to a bad PCV valve allowing blow by, the oil was probably through the entire intake track.

But to answer your question that IM is not the one on my car so if it is dirty it could be from the above reason. Mine shouldnt have that problem due to the check valve, new PCV, catch can, and deleted EGR.

I'm just worried it won't get accurate pressure because the holes that feed that galley are so tiny. There has to be a reason why Mitsubishi disigned a galley in the IM specifically for the PCV valve. Otherwise they would have just put a 3rd source right next to the BOV and FPR sources.

 

[007jimmy]

I totally understand where you are getting at. Worse come to worse hook it up there log it and see if it matches the boost gauge. If not plug the hole back up.

 

[MY1GDSM]

I'm just worried it won't get accurate pressure because the holes that feed that galley are so tiny. There has to be a reason why Mitsubishi disigned a galley in the IM specifically for the PCV valve. Otherwise they would have just put a 3rd source right next to the BOV and FPR sources.

The source it's self will work fine Alone.

Problem comes from the fact that having the PCV and crank case evacuation setup still in place and it drawing from the same source is it's going to throw off the readings.

 

[Calan]

I'm just worried it won't get accurate pressure because the holes that feed that galley are so tiny. There has to be a reason why Mitsubishi disigned a galley in the IM specifically for the PCV valve. Otherwise they would have just put a 3rd source right next to the BOV and FPR sources.

You would be much better off with a dedicated port in the plenum, as close to the throttle plate as possible.

One problem with using the PCV port is that those tiny holes are sourced from the individual runners, close to the valves. Although I haven't actually tested it, I don't believe you would get a highly accurate MAP signal there. It would probably work, but it wouldn't be optimum for SD. I believe it would be susceptible to fluctuations caused by cylinder filling and the PCV system as mentioned above.

Your best bet is to just yank the IM and weld in some dedicated bungs and do it right.

You must be logged in to view this image or video.

 

[Spoolin98]

Thanks guys, I just needed someone to verify that I was taking the lazy/wrong route
I will pull the manifold then.

Craig do you know where I can get aluminum bungs with matching barb fittings?
Like in the picture you posted?

Never mind, I found them on the internet...thanks anyway!

 

[biglady112]

We run two cars with the port you are questioning. One on each side of that galley. One 4 bar car and one 5 bar car threaded straight into the manifold. Both cars perform flawlessly and one is a low 11 second high 130mph fwd car at 6000ft.

 

[kchaazz]

I use a "Calan" catch can setup, which consists of two -8 AN ports on the valve cover to the can, and one -10 AN port from the can to the intake pipe and the PCV outlet port on the VC is welded, and the port on the VC for the valve to intake manifold is plugged, so I thought that the PCV port on the intake manifold would be a nice place for a 1/8 npt x 1/8 compression fitting for the tubing going to my boost gauge. What I noticed is that with the boost/ vac source in the PCV port, I only got -10 vacuum readings, but with it teed between the plenum and AFPR vacuum line, I get -17 vac readings. (Ive got BC 272 cams and 1mm over valves, which is of course why Im getting -17 in comparison to -18 to -22 vacuum at idle)