808Bill

Plumb it in after the MAF?

z driver 88t

Silk, Do you know how the hose attached to the air box? Is there an existing port to tie into or does he drill the airbox and install a vacuum port (something like this, below) to connect the hose?

808Bill

Yes, you got it. You'd want a bigger nipple though. The two mounting pins under the airbox is where they are added.

Scott at Team Harco

Do you have inside information on this? I have not seen this. I'd have to look more closely, but I think those mounts are boxed-in. Might be difficult to run hoses to them.




I just ordered one of these to take the place of the nipple I installed last week. Image does not quite match the description - it is 3/8" NPT to thread into the air box and 5/8" barb for the hose (image is smaller - probably 1/2") This will allow more flow. $9 on Amazon; material is aluminum. Got my order from US Plastics yesterday, when I ordered a bunch of stuff to replace the brass fittings in my interim fix. Turns out they are much too restrictive. Found a similar (HDPE) piece as below, for about $0.58 each. Shipping is $11....


In case you haven't seen it, I attached the outlet of the catch can as shown below. Uses 3/8 hose. Will be replaced with 5/8 hose when I get the next batch of parts.

808Bill

Yes, Silk sent me the details and the picture of his set up that I posted earlier.

Sorry, it should have read between the two mounting pins. I assume horizontally...

soren.911

You need 3/4” fitting from the AOS vent line. I think anyting smaller is too restricted.
I fitted my on the left side of the airbox just under the filter element. This was the only space I found usable with a 3/4” hose.
the I used a 1/2” 90 degrees brass fitting on the oil filler cap and connected a 1/2” hose to the filterbox air duct. The clearance between the cap and engine room lid is very restricted.

808Bill

Can you post a pic of your set up when you have a chance?

sweet victory

That defeats the entire purpose of rerouting it. If you route the aos line in the airbox, oil will settle at the bottom of the box. If you put it after the MAF, it's just going to get sucked right into the engine like it does in the stock location....

808Bill

I was thinking with a catch can inline.

sweet victory

Again...what you're suggesting just defeats the purpose of rerouting. Might as well leave it in the original location with a catch can. Doesn't make sense to drill a hole somewhere in the intake tube to create the risk of an unmetered vacuum leak.

808Bill

Understood. I look forward to hearing what you come up with.

Seems to work for some...

Silk

The real issue with the AOS is the ‘massive’ vacuum it gets exposed to when going of the throttle and the throttle body closes. To prevent this vacuum sucking out the oil fumes without the cyclonal separation doing its work it has this diaphragm. The diaphragm is not perfect, to some extent in extreme situations some oil gets past, furthermore it wears out and eventually fails gradually decreasing the AOS filtration capacity.

The clue of the mod is to move the AOS exit to a less high vacuum position. The most suitable is somewhere before the throttle body. During driving there will be light vacuum to evacuate the cranckcase fumes via the AOS out. As the fumes are still dirty it is best that they do not directly come into contact with the MAF.

It is very important that the AOS vent line is unobstructed by small diameter bottlenecks. By rerouting the vent line you move it to a lower vacuum position. You will need a big enough diameter for compensating for that. Otherwise you risk to have higher crank case pressure. I saw some pictures above of converter pieces. The diameter is way too small to allow proper venting. I would say the min diameter is half an inch or so.

Silk

Related to the picture posted above. A line is still going from the catch tank to the airbox under the filter to create enough under pressure during driving. Furthermore a catch tank is not necessary. You can leave it out to simplify the mod. It is just a more clean solution as without it eventually some oily fumes end up in the airbox and could dirty a bit the airbox inside. Eventually in extreme cases a bit the engine bay.

sweet victory

Not sure if you realize it, but Silk is routing it to the air box, which is before the MAF. If you reroute after the MAF like you suggested, you're only a few inches away from the original location. Hope that brings some clarity why routing it after the MAF like you suggested is a wasted effort.

sweet victory

I brought this up in Bill's blown (but not actually blown) motor thread, but would like to discuss it more here in this dedicated AOS thread.


Before I do anything with my AOS, I would like to toy with the idea of rerouting the AOS line from the intake to the exhaust. The unknown factor here is if the exhaust from a single bank will be able to generate enough vacuum to keep the AOS working properly. I'd still want to run a catch can, and ideally have the bung welded after the second 02 sensor. Oil vapor (not to be confused with oil mist) would then just be vented into the atmosphere.

I have the equipment to measure and monitor the vacuum at both locations (plenum and exhaust), but the dang contractors renovating my house have their dumpster in front of my detached garage that the 996 lives in. It's the only place the dumpster will fit at the moment. Grrrr.