Thread: Puma 2.2 Provent 200 kit

Originally Posted by komaterpillar

blowby is not increased under load, it decreases as the rings are forced out onto the cylinder wall by higher combustion pressures.
On a HEALTHY engine - one with intact compression rings and a good condition bore will have its most blowby at idle or just off idle

I figured there would be a higher relative blowby (i.e. % of total airflow through the engine) at low load, but higher actual blowby (i.e. Litres of gas) under load.

[quote=Toxic_Avenger;2631134]

Might have been a bit of a sweeping statement saying 'none of the above'.

Don't worry I knew what you meant, I was just having a bit of a dig.

On my other car, a nissan 300zx, the PCV valve (2 off) are tapped straight into the intake manifold plenum, after (downstream of) the turbos and throttle bodies. Under boost, the PCV's will be closed, as the pressure of the boost in the intake manifold will close the valve to prevent a boost leak. But this is also the time where you'd expect higher amounts of blow-by. For blow-by to find its way back into the intake side, the blow-by pressure would need to be higher than the boost pressure. In these instances, the mighty VG30DETT engine will often pop a dipstick or find another way to bleed off excess blow-by as the normal route is unavailable.
TLDR, I think this is what the author of the article above was referencing re foul air condition, but on further look, does not appear to be applicable to our engines, as reintroduction of blow-by to the intake side happens upstream of the turbocharger.

Take little notice of Nissan engineering, they still think its a good idea to sit an intercooler on top of a hot engine.

RE Diesel in oil, this is best remedied with frequency of oil change (simple fixes first). Extreme cases of blow by would necessitate more frequent oil changes.

Nailed it. Just explained why you don't need to spend hundreds of dollars cluttering up the engine bay with more junk.