AOS modification.
01-31-2020, 04:43 PM
#211
Rennlist Member
I have used silicone hoses. But you need to spend time with a catalog to find the best shapes and adapters.I used only the best quality USA made hose and thick wall[ or wire reinforced to prevent it collapsing under vacuum. [url]https://www.siliconehose.com/blog/silicone-hoses-at-their-absolute-best-/ Use black so it looks stock -not Ricer red ! I found some import silicone hoses became stiff after heat cycling. The best connectors imho are barbed brass. Another rabbit hole of hours of nerdy research.They are cheaper online than the official Pcar plastic parts.https://fastfittings.com/
Hope this helps
QUOTE=Nick_L;16389343]I'm in the middle of an AOS rebuild right now, replacing the AOS unit with a Provent 200. Everything is put in place but have not yet started the engine due to other works needing done before. In a few weeks.
Something which have not been mentioned is the tubes in the system. Mine where very brittle, basically shattered when trying to bend a bit. They also had beginning cracks in bends and connectors. I think replacing these should be high on the list of to-do when sorting out the AOS. The connectors can be reused if 19mm I.D hose is used.
Hope this helps
QUOTE=Nick_L;16389343]I'm in the middle of an AOS rebuild right now, replacing the AOS unit with a Provent 200. Everything is put in place but have not yet started the engine due to other works needing done before. In a few weeks.
Something which have not been mentioned is the tubes in the system. Mine where very brittle, basically shattered when trying to bend a bit. They also had beginning cracks in bends and connectors. I think replacing these should be high on the list of to-do when sorting out the AOS. The connectors can be reused if 19mm I.D hose is used.
Be cautious when using silicone hose for oil or fuel, silicone works well for everything from baby food to coolant ,except oil or fuel. If useing for oil or fuel it needs to have a fluorocarbon or fluorosilicone liner to last a long time.
I found this out while researching hose for the Ultimate AOS..
02-16-2020, 05:13 AM
#212
Racer
Update about Provent 200.
After testing, this unit will not work. It have a regulator which functions for a usable pressure BUT it needs a lot more air flow to function. When the valve closes it really just limits the flow to 'minimum' which is still so high that vacuum increases in the crank case. The flow is just too small on the M96 3.4L, leading to very high crank case vacuum. I have spent the last week trying to modify the unit(restrictors and/or new valve seat) to function better at low flows but to no vain. Maybe the Provent 100 is a better option. I've had enough of experimenting with this now, so reverting to original for now.
I did a test of the filter, filling it with oil, to see how well it would block in event of the system sucking oil. Well, the oil passes in rather fast pace thru the filter. It doesn't do a good job preventing oil from going to the intake in this case.
Charles, a question came to mind while doing this that you might be able to answer. Why are the vacuum ports on the engine on the heads? why didn't porsche just suck the vacuum from a more center point (say the oil filler tube) to avoid oil going up in the system?
After testing, this unit will not work. It have a regulator which functions for a usable pressure BUT it needs a lot more air flow to function. When the valve closes it really just limits the flow to 'minimum' which is still so high that vacuum increases in the crank case. The flow is just too small on the M96 3.4L, leading to very high crank case vacuum. I have spent the last week trying to modify the unit(restrictors and/or new valve seat) to function better at low flows but to no vain. Maybe the Provent 100 is a better option. I've had enough of experimenting with this now, so reverting to original for now.
I did a test of the filter, filling it with oil, to see how well it would block in event of the system sucking oil. Well, the oil passes in rather fast pace thru the filter. It doesn't do a good job preventing oil from going to the intake in this case.
Charles, a question came to mind while doing this that you might be able to answer. Why are the vacuum ports on the engine on the heads? why didn't porsche just suck the vacuum from a more center point (say the oil filler tube) to avoid oil going up in the system?
02-16-2020, 09:01 AM
#213
Rennlist Member
Update about Provent 200.
After testing, this unit will not work. It have a regulator which functions for a usable pressure BUT it needs a lot more air flow to function. When the valve closes it really just limits the flow to 'minimum' which is still so high that vacuum increases in the crank case. The flow is just too small on the M96 3.4L, leading to very high crank case vacuum. I have spent the last week trying to modify the unit(restrictors and/or new valve seat) to function better at low flows but to no vain. Maybe the Provent 100 is a better option. I've had enough of experimenting with this now, so reverting to original for now.
I did a test of the filter, filling it with oil, to see how well it would block in event of the system sucking oil. Well, the oil passes in rather fast pace thru the filter. It doesn't do a good job preventing oil from going to the intake in this case.
Charles, a question came to mind while doing this that you might be able to answer. Why are the vacuum ports on the engine on the heads? why didn't porsche just suck the vacuum from a more center point (say the oil filler tube) to avoid oil going up in the system?
After testing, this unit will not work. It have a regulator which functions for a usable pressure BUT it needs a lot more air flow to function. When the valve closes it really just limits the flow to 'minimum' which is still so high that vacuum increases in the crank case. The flow is just too small on the M96 3.4L, leading to very high crank case vacuum. I have spent the last week trying to modify the unit(restrictors and/or new valve seat) to function better at low flows but to no vain. Maybe the Provent 100 is a better option. I've had enough of experimenting with this now, so reverting to original for now.
I did a test of the filter, filling it with oil, to see how well it would block in event of the system sucking oil. Well, the oil passes in rather fast pace thru the filter. It doesn't do a good job preventing oil from going to the intake in this case.
Charles, a question came to mind while doing this that you might be able to answer. Why are the vacuum ports on the engine on the heads? why didn't porsche just suck the vacuum from a more center point (say the oil filler tube) to avoid oil going up in the system?
I would imagine the AOS wouldn't function as well for evacuating crankcase windage if it just pulled from the oil fill tube. Pulling from the furthest points in the crankcase most likely ensure a more thorough evacuation of the crankcase. That's my thoughts anyway. Just a guess!
02-16-2020, 12:01 PM
#214
Rennlist Member
I wouldn't be too concerned about high crankcase vacuum. It's going to be different than the stock AOS. We've actually maxed out our manometers when using Total Seal rings on these engines, so it's just a number, not a constant. You won't hurt anything.
I would imagine the AOS wouldn't function as well for evacuating crankcase windage if it just pulled from the oil fill tube. Pulling from the furthest points in the crankcase most likely ensure a more thorough evacuation of the crankcase. That's my thoughts anyway. Just a guess!
I would imagine the AOS wouldn't function as well for evacuating crankcase windage if it just pulled from the oil fill tube. Pulling from the furthest points in the crankcase most likely ensure a more thorough evacuation of the crankcase. That's my thoughts anyway. Just a guess!
02-18-2020, 12:25 PM
#215
Rennlist Member
We have had 3.8 (which have a different AOS setup than all the other engines) with Total Seal rings pull normal manometer readings, however, we have had many other engines max out the manometer and even with the engine off, they will hold vacuum for quite some time. Long story short, I can't give you a firm number to look.
02-18-2020, 05:11 PM
#216
Be cautious when using silicone hose for oil or fuel, silicone works well for everything from baby food to coolant ,except oil or fuel. If useing for oil or fuel it needs to have a fluorocarbon or fluorosilicone liner to last a long time.
I found this out while researching hose for the Ultimate AOS..[/QUOTE]
I found this out when I used silicone hoses for my PVC/catch can mod on my VW
Live a little, learn a little.
I found this out while researching hose for the Ultimate AOS..[/QUOTE]
I found this out when I used silicone hoses for my PVC/catch can mod on my VW
Live a little, learn a little.