CALLING ALL DS3 OWNERS WITH THE THP ENGINE !!!....Who's had new engines ??

[Parafilm]

Czar, would you reccomend the occaisional use of a fuel cleaning additive or similar to help reduce the build up of those carbon deposits? Or is it not worth it?

[Czar]

Czar, would you reccomend the occaisional use of a fuel cleaning additive or similar to help reduce the build up of those carbon deposits? Or is it not worth it?

C'mon have a little think about that ? Any additive you introduce into your fuel tank, won't have any effect on the carbon deposits found and seen on the backs of the inlet valves, the THP engine is GDI (gasoline direct injection) this means that the fuel is injected directly into the combustion chamber, and therefore no fuel passes through the intake manifold or intake runner tracts in the cylinder head, unlike regular port injection where additives introduced into the fuel tank can help, as the fuel washes the backs of the inlet valves keeping any carbon deposit from induced crankcase oil mist vapour to a minimum.

[Parafilm]

C'mon have a little think about that ? Any additive you introduce into your fuel tank, won't have any effect on the carbon deposits found and seen on the backs of the inlet valves, the THP engine is GDI (gasoline direct injection) this means that the fuel is injected directly into the combustion chamber, and therefore no fuel passes through the intake manifold or intake runner tracts in the cylinder head, unlike regular port injection where additives introduced into the fuel tank can help, as the fuel washes the backs of the inlet valves keeping any carbon deposit from induced crankcase oil mist vapour to a minimum.

Fair point that :P

[Dave Clarke]

I guess you've not read my posts correctly, all THP engines and all GDI engines with the exception of Toyota/Lexus suffer from excessive carbonising on the inlet valves!

Which is why anyone chasing more power should remove the rear pcv. Its a good idea bit badly implemented, if the oil was returned to the crankcase instead of ingested into the combustion chamber then there wouldn't be this thread

[Czar]

Which is why anyone chasing more power should remove the rear pcv. Its a good idea bit badly implemented, if the oil was returned to the crankcase instead of ingested into the combustion chamber then there wouldn't be this thread

A considerable amount is returned into the cylinder head return valleys, from the separation troughs. valleys, steps and spiral separation traps, it's only a very small amount of oil particle droplets smaller than 20 microns that pass through the cam cover entrapment passages, and when you consider the amount of carbon deposit build up per miles covered its actually very very negligeable, yes it's a problem granted, that said there is always WMI (water/methanol injection)

[Clarky]

I was told that the Thp engine cost £5000 to replace and thats without labour costs...Just glad she let go under warranty.

[Chris_Blue]

CZAR- are you a computer in disguise?
Youre well clued up
Bit like ZEN in Blakes Seven
CBLUE

[lufc_lad]

What is the PCV and how do you remove it? Surely there would be other implications if it was removed

[Czar]

CZAR- are you a computer in disguise?
Youre well clued up
Bit like ZEN in Blakes Seven
CBLUE

Hahaha no, I'm just a professional race car engineer, race component design to production engineer and semi retired race car driver.

What is the PCV and how do you remove it? Surely there would be other implications if it was removed

You don't remove the PCV as PCV stands for: positive crankcase ventilation.

[Dave Clarke]

A considerable amount is returned into the cylinder head return valleys, from the separation troughs. valleys, steps and spiral separation traps, it's only a very small amount of oil particle droplets smaller than 20 microns that pass through the cam cover entrapment passages, and when you consider the amount of carbon deposit build up per miles covered its actually very very negligeable, yes it's a problem granted, that said there is always WMI (water/methanol injection)

There are some with THP engined Mini's (sorry for swears ) who advocate decoking with water, where the engine is revved to 2500rpm and a steady stream of water is added to the intake flow after the turbo, the heat releases the hydrogen that is surprisingly good at removing the carbon deposits.

[cyclone]

The small amount of oil trapped within the ridged grooved lines of the PCV feed line, is exactly what you would expect to see, the ridged grooves are dong their job, disturbing the air flow enough to encourage oil particles to fall out of suspension, nothing to worry about.

You and (the manufacturers) want as much suspended oil within the crankcase vapour to fall out of suspension before any of it gets to the backs of the inlet valves, as the manufacturers were and are aware that GDI engines would and will suffer from excessive carbon deposit build up on the backs of the inlet valves, so in order to do this as cheaply and as maintenance free as possible, they implement simple ideas, it certainly isn't the best idea by a long shot, that said they have economical cost restraints, and service profits to consider too!

So what you see/saw in your PCV line is a good outcome, it means that the manufacturers simple ideas are helping combat the ever increasing problem.

Wrong, over time, it simply gets lifted back into suspension, however, because the settled oil is heavier than air, it takes a long time for it to be lifted back into suspension, and any that does become resuspended into the air stream, is dependant on velocity to stay suspended, and so some will inevitably fall out of suspension again when changing direction 90º at the bottom of the inlet manifold (plenum) and pool in the void there too, this is a never ending cycle.

First sorry we have kind of hijacked your thread Clarky.


So have given this some thought and this is what I have come up with

Yes you want as much oil as posible to fall out of suspension before the vapour reaches the PVC line. After it reaches that line you would want to keep it suspended to get it to the cylinders in that vapour form as quickly as possible. Any and all oil entering that line has exactly one place to go. To the cylinders, in gaseous or liquid states. There is no logical reason to promote the suspended oil to consolidate to its liquid form. The only way to ensure even distribution is to keep that mist suspended. Though I realise it is impossible to keep all the oil in vapour form. Any pooling must be thought of as a bad thing and minimized at all cost. The forces acting to separate the oil from the air are greater than those required to resuspend the oil. This leads to a build up of oil that is only going to increase till it reaches the manifold in liquid form. Same with any pooling in the manifold voids, they will fill up to a point where a heavy film will be blown down the intake walls to the valves and cylinders exacerbating the valve coking problem and leading to unpredictable and drastic changes in effective octane levels. It is not a never ending cycle for some people it has ended in destroyed pistons and a new engine more than once.
<
The manufacture has limited choices when it comes to dealing with this as the blow by gases must be returned to to be burned, but choices were made in this design that did not pan out in real world engine operation. Hence the revamped RCZ design with the much shorter smoother internal passages to keep that vapour suspended after exiting the final oil separator and evenly distribute it to all cylinders. The cold weather issue is also neatly solved at the same time. If there were just a cold weather problem it would have been much cheeper to just outfit those small markets with the updated manifold instead of implementing a redesign of cylinder head. Any time you start talking new castings and machining it big bucks as opposed to an injection molded piece. Not sure and I might be mistaken but didn't BMW install a heating element at the manifold to combat this in cold climates?

[Chris_Blue]

Hahaha no, I'm just a professional race car engineer, race component design to production engineer and semi retired race car driver

AAHH ZEN not CZAR then
CBLUE

[Czar]

There are some with THP engined Mini's (sorry for swears ) who advocate decoking with water, where the engine is revved to 2500rpm and a steady stream of water is added to the intake flow after the turbo, the heat releases the hydrogen that is surprisingly good at removing the carbon deposits.

When you add water into the air intake flow post turbo, I would think you mean they introduce the steady flow of water through the rear PCV line, there is insufficient heat within the air flow to effectively spilt water into it's two states of Hydrogen and Oxygen, therefore the reaction of any hydrogen contacting the carbon deposit on the backs of the inlet valves will be nil, to split water from plain heat we need temperatures in excess of 2700ºc

Once atomised droplets of water enter the combustion chamber, we have created a state of steam albeit in this instance it is super heated steam, and it is whilst in this state it will effectively clean and remove any carbon from within the combustion chamber.

[Czar]

First sorry we have kind of hijacked your thread Clarky.


So have given this some thought and this is what I have come up with

Yes you want as much oil as posible to fall out of suspension before the vapour reaches the PVC line. After it reaches that line you would want to keep it suspended to get it to the cylinders in that vapour form as quickly as possible. In GDI engines no, as there is no fuel present to wash the backs of the inlet valves, and so we need and want as much of the oil particles to fall out of suspension as possible, that said in regular port injection it's not as critical, due to the fuel wash effect. Any and all oil entering that line has exactly one place to go. To the cylinders, in gaseous or liquid states. There is no logical reason to promote the suspended oil to consolidate to its liquid form. The only way to ensure even distribution is to keep that mist suspended. It doesn't matter whether the oil particles are in suspension or heavy settled liquid, even distribution will take place, as you have the same vacuum pull and sequence from all cylinders. Though I realise it is impossible to keep all the oil in vapour form. Any pooling must be thought of as a bad thing and minimized at all cost. Not just pooling any oil entering the air intake tract for GDI engines is an issue. The forces acting to separate the oil from the air are greater than those required to resuspend the oil. This leads to a build up of oil that is only going to increase till it reaches the manifold in liquid form. Same with any pooling in the manifold voids, they will fill up to a point where a heavy film will be blown down the intake walls to the valves and cylinders exacerbating the valve coking problem and leading to unpredictable and drastic changes in effective octane levels. It is not a never ending cycle for some people it has ended in destroyed pistons and a new engine more than once. And will start the continuous never ending cycle all over again!
<
The manufacture has limited choices when it comes to dealing with this as the blow by gases must be returned to to be burned, but choices were made in this design that did not pan out in real world engine operation. Hence the revamped RCZ design with the much shorter smoother internal passages to keep that vapour suspended after exiting the final oil separator and evenly distribute it to all cylinders. This cylinder head wasn't so much of a redesign to combat the carbon issue, it was simply a logical progression when you introduce dual vanos and inlet valve lift control. The cold weather issue is also neatly solved at the same time. If there were just a cold weather problem it would have been much cheeper to just outfit those small markets with the updated manifold instead of implementing a redesign of cylinder head. Any time you start talking new castings and machining it big bucks as opposed to an injection molded piece. Not sure and I might be mistaken but didn't BMW install a heating element at the manifold to combat this in cold climates? Not as far as I am currently aware.

.....

[Czar]

AAHH ZEN not CZAR then
CBLUE

Hahaha you could say that.