Silk

Does anybody of you can exactly tell me where the breather hose on the air intake between airbox and throttle body goes to?

As far as I know this hose is only present on mk2 tiptronic cars.


I reused the photo from this topic: https://rennlist.com/forums/996-foru...onic-hose.html

Silk

The line is connected to the venturi line which is in connection with the brake booster. It is also called a sucking jet pump. As the venturi effect will create a higher vacuum then can be found in the intake manifold.

For the tiptronic it is called vernuri line and is part # 996 110 170 51
It interconnects the air intake before the throttle body and the intake manifold part # 996 110 151 01

Its function is to provide a steady idle rpm for the tiptronic cars when halted and holding the brake. When stopped the TB is closed so a vacuum is created in the intake manifold. Via the venturi line some air is drawn into the engine. Mowt probably it has to to with the additional load of the tiptronic transmission when in Driving mode.

The rotating parts in the torque converter create an external load so rpm's could be more irregular. The additional air solves this. Most probably also to compensate when releasing the break and driving off. Is that correct?

The venturi also keeps air speed up during gear changes with the tip. Removing it will create a loss of performance between gear changes, especially between 4-5 gears (I quoted here Jake Raby).

As I converted my tip to a manual for now I will just close off the loose end. Will try to figure out which parts I need to convert this part of the engine to a manual too.

wyovino

Just curious about the cost of switching out the tip for a manual. My tiptronic transmission will eventually need a rebuild for about $6k.

Silk

You have a PM

gdm92

hi all, I was hoping someone could help me understand whether it's possible that a manual (not swapped) c4s (not a x51 car) has the Venturi tube you see in the picture that I always thought is only present on trip or turbo cars. Have you even seen it before? I'm going back to stock airbox and noticed the tube so I'd have to buy a trip airbox to fit that tube in the intake connector to airbox. However I'm very confused on why it's there in the first place. Any suggestion?



Tube that usually is in trip cars.

996-CAB

Silk,
Using the same image, what is this white round thing that plugs into the plenum? I was replacing that coolant hose connector and discovered it was just hanging loose and no longer plugged into the plenum. No idea how long that had been going on!

Porschetech3

@gdm92 the venturi tube is only used on the Tiptronic cars. Your car ( manual) must have had an engine installed from a Tiptronic car...

@996-CAB the round white/black valve is a vacuum check valve, it allows vacuum to only go one way and connects to the divers side rubber intake boot on the bottom... being loose will cause a small vacuum leak..

gdm92

interesting, the no. seems to match with the warranty database I got when I bought it.. I guess regardless, if it's a manual though I shouldn't care as much if that tube is connected to the airbox (asking since I ended up buying an airbox with the additional small hose to attach that one). Right?
in other words, does it look to you what I think it is or you think it's something else?

Porschetech3

You are correct, with the manual trans you should not care whether that venturi hose is used or not.. As you can see, the Fabspeed Carbon Fiber Intake actually has the hose plugged off defeating the venturi function...But also hooking it up to the rubber intake hose will not hurt and will actually give a bit more vacuum to the power brake booster under certain conditions..

gdm92

do I have a power brake booster being a manual?
big mystery on why I have that tube...

Porschetech3

Yes, all 996's have a vacuum assisted power brake booster..

Your car likely does not have the original manual engine installed..

gdm92

is there any way I can find out other than comparing the warranty sheet from porsche to the engine no?

Porschetech3

You can buy the Certified build sheet from Porsche that will have the original engine #.

You can sweet talk a Service Manager at a Porsche Dealership to supply you with all warranty repair documents..( with previous owners info redacted)

Then compare your installed engine #...

Nate.Evans

The 40 Jahres have the Venturi tube and they’re only Manual transmission. Not sure if that means they’re on x51 equipped cars???

Porschetech3

Yes, they are on x51 cars also due to the larger cams with less vacuum at low RPM...