cheap aos fix

[The Radium King]

found this on planet 9:

70 cent VOS AOS mod

the thinking is reduce the amount of vacuum drawn in order to reduce strain on the aos and reduce oil ingestion during high-g cornering.

[JFP in PA]

Originally Posted by The Radium King

found this on planet 9:

70 cent VOS AOS mod

the thinking is reduce the amount of vacuum drawn in order to reduce strain on the aos and reduce oil ingestion during high-g cornering.

When you reduce the vacuum pulled, you open up another can of worms: ring seal problems. Like most modern engines, the M96/97 uses very low tension rings on the pistons, the only way to get them maintain seal is to reduce the atmospheric pressure in the engine's sump (read pull a vacuum). The higher the vacuum level, the better the ring seal, reduce the vacuum and the ring seal deteriorates. Bad idea.

[The Radium King]

understood. however, is there an optimum amount of vacuum that perhaps gets exceeded in certain situations? also understanding that vacuum is not flow, so static vacuum would be maintained regardless of the size of the orifice. reducing the orifice would only limit the rate of change of vacuum level.

[JFP in PA]

Originally Posted by The Radium King

understood. however, is there an optimum amount of vacuum that perhaps gets exceeded in certain situations? also understanding that vacuum is not flow, so static vacuum would be maintained regardless of the size of the orifice. reducing the orifice would only limit the rate of change of vacuum level.

The intake system is only capable of generating vacuum in a limited range; hooking up a vacuum gauge and watching swing while driving will demonstrate the point. Placing an orifice in a vacuum line will slow the rate of vacuum development, but not prevent it from reaching its maximum level.

Point here is you are trying to control oil consumption into the engine under certain conditions usually met on the track. Rather than trying to restrict the vacuum, work on controlling the oil movement...............

[The Radium King]

that's fair. I was thinking the benefits of this solution might be that it solved two problems - track oil ingestion and aos failure (as opposing to just an improvement in oiling which tends to be expensive and intrusive). but, if the amount of vacuum tends to remain steady then a moot point, unless you see any spiking of vacuum during hard transitions on/off throttle? then it might reduce the spikes and limit strain on the aos while still allowing vacuum to develop. there is one comment in the linked thread about ipd deleting one of the aos connections on their plenum; uncertain on the thinking on that one?

[JFP in PA]

The AOS fails due to a plastic part being exposed to heat cycles and oil vapor. Over time, they get brittle and crap out. Altering the rate vacuum levels develop might slow that process very slightly, but it would not prevent it, and I would be more concerned about what the rings are doing while the vacuum is low. As I noted above, restricting vacuum will slow down but not stop the development of maximum vacuum in the system.