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Discussion Starter #1 (Edited)
hey,lads,
A friend of mine told me that lots of the issues with the HFV6 are down to inefficient PCV system that leads to extremely high pressure in the heads, which damages seals and keeps high temperature as well. In his opinion, the pcv valve is not big enough and the holes are too small to let the pressure out. Any ideas on how to improve that are welcome.
 

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hey,lads,
A friend of mine told me that lots of the issues with the HFV6 are down to inefficient PCV system that leads to extremely high pressure in the heads, which damages seals and keeps high temperature as well. In his opinion, the pcv valve is not big enough and the holes are too small to let the pressure out. Sny ideas on how to improve that are welcome.
There is a modification - Chrysler/GM instituted, to drill out the holes on the rear head vents - posted on this on Brera rebuild/modifications.

However, he is really taking the pee, to suggest that crankcase pressurisation is the cause of elevated cylinder head temperatures.

The problem is categorically the manifold cats, in conjunction with the Alfa Valve timing - 2.5 deg. NVO. The valve stem seals suffer, for the same reason the oil suffers - elevated cylinder head temperatures. The PCV system, does suffer; is also a victim, and it does result in oil in the inlet tract beyond the MAF. But that is temperature related, which is directly attributable to the Man - cats and valve timing.

Removing the man cats greatly reduces the problem and is worth doing before any other consideration. Try it! You can always put them back. But you won't - because it is true!

But in conjunction with different valve timing, engine temperatures are much more sensible. And then it no longer remains a G.M./Holden engine. Despite Alfa not deserving any credit!
 

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Discussion Starter #3
So, in your opinion, by de-cating the headers and going from NVO to PVO, the need of improved PCV will be rendered mute?
Anyway, I saw videos on the topic. Like that one
 

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So, in your opinion, by de-cating the headers and going from NVO to PVO, the need of improved PCV will be rendered mute?
Anyway, I saw videos on the topic. Like that one
I saw that video a long while ago. That is not a PCV. Well it’s not a valve. The Alfa has a similar take off. But the actual valve on the Alfa is a solenoid and it costs £120 plus!

The problem is not made any easier by virtue of, not only are there oil fumes, but water, a function of “Blow By”.

The poor windage suppression in the sump causes the oil fumes and the water to emulsify. The net effect is, with the very high cylinder head temperatures, it allows the emulsified oil and water + HC’s to form a plaque, coating the heads and cams with a crust.

Getting oil temps down is key to reducing emulsification.

I have done lots of mods to my engine, all intended to reduce temperatures, emulsification, windage, oil surge and increase oil flow/pressure.

Were I to do another engine, or a thousand more, I would do the same. Possibly more.

It is essential to get oil temperatures down and key is the removal of the Manifold Cats.

If you want improved - much, much improved bottom end torque and increased power however, the Alfa camshafts have to go in the bin.

And Mace are not the answer.
 

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Discussion Starter #5
Alright, but why the difference in the gunk accumulation in the two banks?
 

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Alright, but why the difference in the gunk accumulation in the two banks?
It is true, the ventilation on the rear bank is not as good as the front. The rear having those small orifices which Chrysler/GM enlarged. And they are furthest away at the rear right.

But, and I know it is monotonous, there are substantial differences in temperatures between banks as well. The rear bank valve timing, and ignition timing being different from the front due to the higher oil pressure setting the vvt timing much quicker on the front, than the back. So the tell - back comes early from the F/B position sensors.

But, the rear bank tell backs are always late - why the error code is invariably the R/B exhaust cam pos sensor.

This results in unequal power strokes, increased losses and differing bank temps. The front bank man cat gets hotter than the rear one, because the slow to respond R/B pos. sensors suggest to the ECU, the engine is rotating slower and therefore it sets exhaust timing much too advanced.

The exhaust camshafts are max advance when engine off and at low revs.

But, it is the tell back from the rear bank that is late in telling the ECU to predict the valve timing for the front bank, not late because the engine is slower.

Consequently the front bank exhaust camshaft is set at an angle - to open - earlier than it should, with the engine making serious power - too serious for the exhaust valves to open that early.

So extremely high temperature exhaust gases + higher unburnt emissions get stuffed into the front manifold cat.

The reverse is true of the rear bank man cat.

All because of poor oil pressure/flow rate potential to sustain pressure.

Which is why we get timing Chain slap and crap vvt response, leading to rubbish economy, and the engine dynamics of a snail.
 
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