My understanding of the AOS, vacuum and low tension rings is this. The primary advantage of low tension rings is free HP due to reduced friction on cylinder walls. The second part is this, The AOS is an emission device. It is there to capture and reduce blow-by from combustion in the crankcase, and it works like this.
The pressure from combustion helps seal the rings against the cylinder and piston ring lands. As the piston approaches BDC energy is spent and pressure in the cylinder begins to decrease. As cylinder and crankcase pressures approach equalization it causes the rings to lose contact resulting in blow-by. Vacuum in the crankcase supplied by the AOS allows the low tension rings to maintain contact further down the stroke resulting in reduced blow-by.
So if you don't have to smog your car, the AOS is not required, you will simply have a little more blow-by. This is simplified for understanding, and does not address leakage and trapped pressure between the oil control rings that contribute to the problem. Bottom line if you have an off road only car, Stick a vent cap on the oil fill tube and rock and roll.
Of course I could be wrong.....
Last edited by 911monty; 10-07-2019 at 01:09 AM.
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