Pcv vent to air and intercooler advice for thp 155 project

[Sirdan555]

So, continuing to work on beasting up my project DS3 thp 155. So far I've done an air intake, uprated the internals of the recirculation valve, uprated the brakes with ebc green stuff pads and rotors with cuts, and got a sports cat milltek system.

Also I've put on a Sachs clutch which is uprated, upgraded the high pressure fuel pump, and uprated the coil packs and spark plugs.

So far just done a stage 1 remap locally. I'm. Going to get a better intercooler next and boost pipes and then probably visit Jamie (two hundred miles + away but seems worth it) for an ultimate remap.

So, just two questions. Firstly what intercooler would you go for? The airtec one seems out of stock with a new one from them coming after the summer?

Secondly, I was fed up with the idea of oil and stuff going back in to the air intake via the pcv, especially as I spent three hundred pounds on a walnut blast before doing all the work above. So I've taken the pcv lines out of the intake, blanked off the holes in the air-intake, and attached hoses to the ends of the pcv tubes so they discharge their filth below the engine. Is this a terrible idea that will lead to some sort of issue. I really couldn't be bothered with catch cans as I understand they don't catch everything.

Thanks for any advice.
Dan

[V3nn3tj3]

Hi Dan. Some information about the PCV system and what (not) to do.
First let have a closer look to why we have a PCV system. The purpose of this system is to not have the engine running with internal pressure. This means that without a pcv system or hole somewhere the crankcase, rocker cover, etc would be pressurized and this would lead to the dipstick or something else flying off into the air. And the car would be burning oil so badly that there won't be any oil left.
But where does the pressure come from ? The piston travelling downwards creates a pressure inside the crankcase, this pressure builds up after time. The build up is possible because some exhaust gasses get inside the crankcase as the piston rings are not a 100% air thight, more air in the same space means a higher pressure. The pressure would build up to such a big pressure that the air inside that crankcase would start to slip inside the cilinder past the piston rings. On some strokes the air will be going inside the crankcase on other strokes inside the cilinder. The car would be starting to burn the oil. The buildup would become so great after time that the pressure will make the dipstick blow out of the engine to release this pressure.
So what did they come up with to fix this problem. On really old cars they just made a hole big enough to vent this pressure, this is positive ventilation. The pressure is released when needed. On old cars they used the same principle but with a hose running down the underside that created a vortex which in turn created an underpressure in the hose and there for inside the crankcase, this is negative ventilation. Now the reason for negative ventilation is that sometimes positive ventilation kept dirty fumes inside the engine which contaminated the oil. Remember the exhaust gasses that contain water, fuel and sulfuricacid. This is very bad for the oil. Now with the euro norms that didn't really like what was in these fumes and they came up with the best idea ever. Let's just burn these fumes and all will be well. Except, it's not very eco friendly and doesn't play well with direct injection. Now on a car using normal injection (or others) the fumes will not stick to anything inside the engine as everywhere the fumes go, also fuel goes. This fuel cleans everything the fumes leave behind and that's why, untill the newer direct injection engines, there weren't any problems. The problem we are facing now is that the fumes do leave a residu but the places where it travels are never cleaned (with fuel). The leaves us with dirty intake valves. The valves go so hot and the residu sticks to these hot valves leaving the buildup.
Now on to our engine. There are 2 PCV port. Both are connected to a series of valves inside the rocker cover, the reason why is because one line goes to the intake of the turbo, the other to the intake of the engine. And here is how the valves operate. When not having boost (under 2500k rpm or so) the back pcv is open and there is an underpressure in that line. Sucking onto the back pcv port. Fumes travel directly to the engine intake. Now, when there is boost the back pcv get's closed off by the turbo pressure and only the front PCV can be used. You don't want turbo pressure inside your crank case as the oil would be pushed out through every seal. The front PCV is connected to the turbointake which make the fumes go through the hole intake system incl. Intercooler. Now i can't remember if the front is open when the back one is. But don't take so. This is how the system works.
What can we do about this? There are alot of opinions and fixes. And most are not that bad, some are a nono. But keep in mind that whatever you do there are some downsides.
1. You can keep everything stock but that leaves us with dirty engines.
2. Close everything off. But dipsticks flying out are not really the solution.
3. You can install a catch can but leave all the lines intact.
3a. Put an occ on back line, only catch fumes when driving under no boost
3b. Put an occ on front line, only catch fumes when driving under boost.
3c. Put an occ on both front and back port.
You have to keep in mind that when using the underpressure of the lines, the fumes are sucked through the occ at a very fast pace, this makes me think that they may not have enough time to condense inside the occ. Also blocking the back port is not really and option as you won't have any ventilation when you have no boost.
4. Vent to air. This one is tricky! You CAN'T do this without rebuilding your rocker cover. There are valves inside the rocker cover that are opened by the underpressure from the pcv lines. Just connecting 2 hoses to it will do nothing. The pressure will be released as the valves will open, but the internal pressure will have to be high enough to do so, and you don't want any pressure at all!!
Some people say that this is very bad. The reason for this is mainly that the bad fumes are not all removed from the engine and you're not eco friendly when doing this mod.

What i did was remove all valves inside the rocker cover. Close the back pcv port and have an always open port on the front. This port goes to a occ and this occ vents to air. I have yet to find bad oil in my engine and already changed it twice since doing the mod. The oil wont last 30k km as citroen says but i service my car every 10k km anyway. What i get inside my occ is some oil (duh). But when having 100ml of content, 70ml is just water. This is watervaper from the exhaustgasses...

So it's up to you but please revert the changes you have done now and have some good thinking sessions about it before messing with this system. Took me a few months to make up my mind and alot of conversation with engine builders and mechanics.

[V3nn3tj3]

Oh btw, pressure buildup is also because of the oil vapours... Forgot that bit.

Ans yes, water, and yes, piston rings are ok, compression test was perfect.

[Sirdan555]

That's a really comprehensive reply. Thanks very much and I'll have a good think about it. Do you mean that the negative pressure from inside the air intake is necessary for the pcv to operate properly? So that if you vent to atmosphere the pcv isn't actually venting as much as it should?

Thanks
Dan

[V3nn3tj3]

Yes Dan, but it seems to me that the THP engine has enough overpressure (positive ventilation) to overcome this problem. This is my opinion and might be wrong or only true for some engines. No 2 engines are the same.

[Sirdan555]

That's what I was thinking, if we're right on that presumably venting to atmosphere directly would not harm the engine?
Dan

[Czar]

So, continuing to work on beasting up my project DS3 thp 155. So far I've done an air intake, uprated the internals of the recirculation valve, uprated the brakes with ebc green stuff pads and rotors with cuts, and got a sports cat milltek system.

Also I've put on a Sachs clutch which is uprated, upgraded the high pressure fuel pump, and uprated the coil packs and spark plugs.

So far just done a stage 1 remap locally. I'm. Going to get a better intercooler next and boost pipes and then probably visit Jamie (two hundred miles + away but seems worth it) for an ultimate remap.

So, just two questions. Firstly what intercooler would you go for? The airtec one seems out of stock with a new one from them coming after the summer?

Secondly, I was fed up with the idea of oil and stuff going back in to the air intake via the pcv, especially as I spent three hundred pounds on a walnut blast before doing all the work above. So I've taken the pcv lines out of the intake, blanked off the holes in the air-intake, and attached hoses to the ends of the pcv tubes so they discharge their filth below the engine. Is this a terrible idea that will lead to some sort of issue. I really couldn't be bothered with catch cans as I understand they don't catch everything.

Thanks for any advice.
Dan

Only your conscience for other road users safety is in question, as you decided that evacuating crankcase oily residue onto the underside of your car and onto the road surface, is/was the best solution to your dismissal for fitting oil catch cans, oil residue, wet road, what could possibly go wrong !!

Be a good chap and reconsider fitting good oil catch cans, for your safety and your fellow road users.

Hi Dan. Some information about the PCV system and what (not) to do.
First let have a closer look to why we have a PCV system. The purpose of this system is to not have the engine running with internal pressure. This means that without a pcv system or hole somewhere the crankcase, rocker cover, etc would be pressurized and this would lead to the dipstick or something else flying off into the air. And the car would be burning oil so badly that there won't be any oil left.
But where does the pressure come from ? The piston travelling downwards creates a pressure inside the crankcase, this pressure builds up after time. The build up is possible because some exhaust gasses get inside the crankcase as the piston rings are not a 100% air thight, more air in the same space means a higher pressure. The pressure would build up to such a big pressure that the air inside that crankcase would start to slip inside the cilinder past the piston rings. On some strokes the air will be going inside the crankcase on other strokes inside the cilinder. The car would be starting to burn the oil. The buildup would become so great after time that the pressure will make the dipstick blow out of the engine to release this pressure.
So what did they come up with to fix this problem. On really old cars they just made a hole big enough to vent this pressure, this is positive ventilation. The pressure is released when needed. On old cars they used the same principle but with a hose running down the underside that created a vortex which in turn created an underpressure in the hose and there for inside the crankcase, this is negative ventilation. Now the reason for negative ventilation is that sometimes positive ventilation kept dirty fumes inside the engine which contaminated the oil. Remember the exhaust gasses that contain water, fuel and sulfuricacid. This is very bad for the oil. Now with the euro norms that didn't really like what was in these fumes and they came up with the best idea ever. Let's just burn these fumes and all will be well. Except, it's not very eco friendly and doesn't play well with direct injection. Now on a car using normal injection (or others) the fumes will not stick to anything inside the engine as everywhere the fumes go, also fuel goes. This fuel cleans everything the fumes leave behind and that's why, untill the newer direct injection engines, there weren't any problems. The problem we are facing now is that the fumes do leave a residu but the places where it travels are never cleaned (with fuel). The leaves us with dirty intake valves. The valves go so hot and the residu sticks to these hot valves leaving the buildup.
Now on to our engine. There are 2 PCV port. Both are connected to a series of valves inside the rocker cover, the reason why is because one line goes to the intake of the turbo, the other to the intake of the engine. And here is how the valves operate. When not having boost (under 2500k rpm or so) the back pcv is open and there is an underpressure in that line. Sucking onto the back pcv port. Fumes travel directly to the engine intake. Now, when there is boost the back pcv get's closed off by the turbo pressure and only the front PCV can be used. You don't want turbo pressure inside your crank case as the oil would be pushed out through every seal. The front PCV is connected to the turbointake which make the fumes go through the hole intake system incl. Intercooler. Now i can't remember if the front is open when the back one is. But don't take so. This is how the system works.
What can we do about this? There are alot of opinions and fixes. And most are not that bad, some are a nono. But keep in mind that whatever you do there are some downsides.
1. You can keep everything stock but that leaves us with dirty engines.
2. Close everything off. But dipsticks flying out are not really the solution.
3. You can install a catch can but leave all the lines intact.
3a. Put an occ on back line, only catch fumes when driving under no boost
3b. Put an occ on front line, only catch fumes when driving under boost.
3c. Put an occ on both front and back port.
You have to keep in mind that when using the underpressure of the lines, the fumes are sucked through the occ at a very fast pace, this makes me think that they may not have enough time to condense inside the occ. Also blocking the back port is not really and option as you won't have any ventilation when you have no boost.
4. Vent to air. This one is tricky! You CAN'T do this without rebuilding your rocker cover. There are valves inside the rocker cover that are opened by the underpressure from the pcv lines. Just connecting 2 hoses to it will do nothing. The pressure will be released as the valves will open, but the internal pressure will have to be high enough to do so, and you don't want any pressure at all!!
Some people say that this is very bad. The reason for this is mainly that the bad fumes are not all removed from the engine and you're not eco friendly when doing this mod.

What i did was remove all valves inside the rocker cover. Close the back pcv port and have an always open port on the front. This port goes to a occ and this occ vents to air. I have yet to find bad oil in my engine and already changed it twice since doing the mod. The oil wont last 30k km as citroen says but i service my car every 10k km anyway. What i get inside my occ is some oil (duh). But when having 100ml of content, 70ml is just water. This is watervaper from the exhaustgasses...

So it's up to you but please revert the changes you have done now and have some good thinking sessions about it before messing with this system. Took me a few months to make up my mind and alot of conversation with engine builders and mechanics.

Your information is I'm sure offered with good intention to help those with less mechanical understanding than yourself, however, sometimes it's best not to offer mechanical advice, when that advice only leads to misguidance.

The camshaft cover/rocker cover is not a component that is serviceable, the valves/flaps have no preload, therefore will open/close without vacuum !!

[V3nn3tj3]

Nope, they will only open when pressure is build up. I've opened one (as you did) and i rebuild it and using it atm. It's not only the flaps inside the rockercover, there are other chambers, springs and flows at play. Gravity is a bitch and keeps these flaps closed untill the pressure is big enough to overcome this force... You don't even want 10 or 100 pascal over overpressure inside the engine.
Czar, i understand and i am convinced that you know alot about cars. But i never seen one positive reaction if it's not your opinion. Please keep in mind that we are all here to help and i can live with the fact that i might be wrong but the way your telling me is just wrong... And i'm not here to start a flame war but...

Verstuurd vanaf mijn ONEPLUS A3003 met Tapatalk

[Czar]

Only your conscience for other road users safety is in question, as you decided that evacuating crankcase oily residue onto the underside of your car and onto the road surface, is/was the best solution to your dismissal for fitting oil catch cans, oil residue, wet road, what could possibly go wrong !!

Be a good chap and reconsider fitting good oil catch cans, for your safety and your fellow road users.



Your information is I'm sure offered with good intention to help those with less mechanical understanding than yourself, however, sometimes it's best not to offer mechanical advice, when that advice only leads to misguidance.

The camshaft cover/rocker cover is not a component that is serviceable, the valves/flaps have no preload, therefore will open/close without vacuum !!

Nope, they will only open when pressure is build up. I've opened one (as you did) and i rebuild it and using it atm. It's not only the flaps inside the rockercover, there are other chambers, springs and flows at play. Gravity is a bitch and keeps these flaps closed untill the pressure is big enough to overcome this force... You don't even want 10 or 100 pascal over overpressure inside the engine.
Czar, i understand and i am convinced that you know alot about cars. But i never seen one positive reaction if it's not your opinion. Please keep in mind that we are all here to help and i can live with the fact that i might be wrong but the way your telling me is just wrong... And i'm not here to start a flame war but...

Verstuurd vanaf mijn ONEPLUS A3003 met Tapatalk

Crankcase windage = positive pressure, hence why I refere to the valves/flaps having the ability to open/close without vacuum !!

Gravity is not a bitch, Gravity is a constant, Mother Nature is a bitch, LOL.

Engine positive crankcase windage, (pressure) this has increased over the years as designers/manufacturers strive for greater engine fuel efficiency, one of the ways to achieve this is, to reduce friction within the engines components, relieving piston ring compression tension is one, this has the disadvantages of allowing more compression combustion blowby whilst increasing engine oil consumption.

I do give positive reaction feedback when necessary, or have no need to comment when what is being written has more fact than misguidance.

[Sirdan555]

Thanks both. For now I've decided to continue to vent to atmosphere, but I've ordered a catch can and breather filter to help reduce the chance of causing issues for others.
Thanks
Dan

[Sirdan555]

[ATTACH]14450[/ATTACH][ATTACH=CONFIG]14451[/ATTACH]]14449[/attach]

[Sirdan555]

Blanked off the holes in the air intake properly and set up an oil catch can system tonight. Be interesting to see what I catch

[Drummond Base]

But i never seen one positive reaction if it's not your opinion.

Aint that the truth.

[Sirdan555]

Had to replace the hoses as the previous ones had sort of melted. Tip to anyone doing catch cans - make sure you get decent hoses!

[V3nn3tj3]

Melting because of the oil vapor or melting because of the heat ? I made brackets to hold it up from the engine. Don't have a good picture but you can see it on here.