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What does this do? The Rear Plenum on the Intake Manifold with vacuum actuated flap?
Hello all. Can someone tell me what this does? It is the rear plenum on the intake manifold. It has a vacuum actuated flap that closes when vacuum is applied and when there is no vacuum it is open. Open is the default position.
I'm just curious as to what the heck it does. For anyone that cares, this is the part number for it: 99611012053
Okay, I will bite. This is totally off the top of my head but I think it changes the effective length of the intake after the throttle body which effects low and high RPM torque and horsepower
I was kind of wondered about this too, as its currently out of the engine. Obviously, the throttle body and forward plenum controls the main air intake to both left and right sides, but the rear would seem to affect the balance between the two sides?
Re: 2nd plenum - the one closer to the front of the car.
I found the flap actuator seized, the small post that snaps into the arm was corroded and, as a result, didn't allow the flap to rotate open.
how to test without removing:
It's possible to gain access to the 2nd plenum once you remove the first one (the one attached to the throttle body). Loosen the clamps on the 2nd plenum and rotate it so the vacuum powered actuator is at the bottom. Pull the vacuum line off the switch over and suck on the line (with your mouth or pump). You should see the actuator arm moving in, this rotates the flap.
My solution was a bit McGiver ...but it works well.
This is very interesting and I didn't realize our cars had this technology. I saw that second plenum, but didn't know what it did. I've watched several Engineering Explained video where he talked about the back pressure wave that is created when the intake valve slams shut. In an older video he showed how Porsche has been doing this on newer cars, but I couldn't find it in time for the release of this comment. In a recent video, see below, they improved on this idea on the new GT3. The M96 has the roots of the concept in play. Pretty cool that we get to drive such sophisticated machines.
This is the meat for why I don't think we should use any aftermarket products in the air induction system. Air Filter, Filter box, plenum and all related components. You screw with that, and all the Porsche calculations for resonance go out the window...
Please remind me the difference between M96/01/01S/02/02S/04/03/03S and M96/76/79/80? The engine is the M96. I don't know what to do with the rest of the numbers.
05-15-2017, 02:02 AM
What does this do? The Rear Plenum on the Intake Manifold with vacuum actuated flap?
