85euro928

Is anyone out there with a 16V euro using the air pump port at the back of the head to scavenge crank vapors from the oil filler area? I've read that some have tied this into the exhaust at the wye, etc but I'm wondering if anyone has tied it into the euro exhaust port at the head and if it works? On a related question does anyone know if there's suction or pressure at this port? I would think that since the air pump is tied in to here there really has to be negative pressure at the port otherwise the exhaust would be pushed up into the air pump?

123quattro

I'm not sure, but I'd imagine there is a check valve on that port. If it's in the exhaust, it will be positive pressure.

I think you need something like this to accomplish what you are talking about.

http://www.summitracing.com/parts/vpe-11189

mark kibort

the port is a tiny hole in the exhaust port. the air pump pushes a little air into that port to mix air with the exhaust gases for emissions benefit. i dont know what you want to do, but im sure nothing can be done with that port.
there is very little pressure in the port, via the exhaust flow, thats why the pump, which is positive pressure , is able to feed air into this small pin hole port.

85euro928

Thanks Mark, that's what I needed to know.

Dave928S

The drilling which goes from the front of the head to the back is 10mm ID, and has a plug at the front and the air pump connection at the back. The drillings which communicate with that long drilling, from each exhaust port, are 4mm ID. So ... you have 4 X 4mm vent holes connected to each head drilling, with both of those drillings connected via the air pump manifold to the air pump line = 8 x 4mm holes from exhaust ports to the air pump manifold at the rear.

That cross sectional area of holes is quite a significant connection, and certainly not a 'tiny hole' or 'pin hole port'.

I don't know flow rates or pressures of the air pump, or pressures at those bleed holes in the port, and that's what you would need to know to make an informed decision as to whether you can do something else with the port drillings.

The fact that the main drilling on each head accumulates some carbon, however, would indicate that the air pump may have to overcome some positive exhaust pressure.

Here are some pics. One looking down the air pump 10mm drilling, showing light coming through the drilling through to the exhaust port, and one of an exhaust port drilling (each exhaust port has one).

Edit: You would be better, and more emission compliant, to feed crankcase vapours to the intake, to be consumed in the combustion process, and not fed to the exhaust.

mark kibort

so you just want to find a place to drain that crankcase air pressure and oil dispersion? the air pump provides positive pressure, so its one way. if you dont have anything connected , you have what sounds like an exhaust leak... Its very INSIGNIFICANT, dave, because i actually know this by experience. (nice pictures by the way... thanks!) Yes, ive run the car without the plug.... was trying to figure out where the clicking was coming from. turns out, the shop left out the plug on the front and i didnt notice it missing. SO, i had a slight clicking noise. Like an exhaust leak. so, its very easy to over power with some slight pressure from the air pump to dump air into the port to help emissions. venting crankcase, might just pressurize the crankcase more. dumping it into the intake is how i run the race car and there never has been any adverse effects. Ive extended some hoses to make it harder for the oil to climb out, and that has seemed to work well.

GlenL

And there's a valve.

Exhaust scavenging PCV systems use a pipe that sticks out into the exhaust flow. That causes the gases to be sucked in.

Me, too. I plumbed the the exhaust from the catch can into the air cleaner which has a few capped fittings on it.

Alan

You could swap the air pump for a vacuum pump which could better scavenge the crankcase mist via an oil separator (under all running conditions) - and then feed the cleaned air back to the filter box.

Alan

85euro928

Based on Dave's info I'm going to pass on this idea. I was just thinking that since I've already removed the air pump the port at the back of the head would be available to provide some scavenging instead of using the port at the bottom of the intake. I'm already running a pan spacer and one of the older style filler block off plates but I still get some oil in the intake. I'm thinking if I modify the filler diverter at the bottom of the oil filler to function more like the "modern" one's, modify the stock filler/separator like Carl's 16V system, and install a Provent, that should allow me to feed the outlet of the Provent system into the intake and not have any breathing problems. I'll let you know this spring how it works.

123quattro

I wouldn't plumb the PCV system back into the intake. If there isn't a blowbye problem it won't stink if vented to atmosphere. If there is a blowbye problem, you don't want to be ingesting the oil and increasing the potential for knock anyway.

Dave928S

Definitely a good idea to pass on the connection to exhaust port drillings. You could overcome the few pounds of back pressure, as the air pump does, and feed vapour in, but it's not a real solution ... and it's dirty. Venting to atmosphere falls into the same category.

The main problem with the 16V crankcase ventilation system, IMO, is that very short connection between the oil filler neck and the intake plenum; which gives oil mist and droplets an easy downhill path to the intake plenum. The oil builds up in a pool in there, and when you floor it, it gulps that puddle of oil. Lengthening that connection hose, and passing it through a provent, along with other refinements to make it more difficult for oil mist/droplets to get through, works wonders.

Alan

Agree no need to vent to atmosphere (or exhaust ~same thing) - you just need a better separation solution than the stock one. On earlier cars that is enough, on the GTS it still isn't quite enough on its own.

Alan

mark kibort

yep, that does work to an acceptable extent.... more so with the S4, and probably different types of oil have different misting characteristics as well.