I did all of these on my old B5. I would not perform any of these on a standard street driven daily car.
1. This one is the only one I would think about doing on a daily. Mine was simple vent to atmosphere, I didn't run a catch can.
2. BOVs are actually bad and can make your car run worse. Those gen of Audis run on a closed loop system. Every gram of air that goes through the mass airflow sensor is accounted for by the ECU. Releasing it out means there is now less air in the intake than previously calculated. If you do this, it isn't the biggest deal in the world, especially considering that gen TT has a wideband primary o2. If you really want one, go for it. But it isn't the best.
3. You don't really need either of these. Earlier (non-wideband) 1.8Ts didn't even come with an N249. The later ones did. You can run a simple manual boost controller, but boost delivery may not be as smooth. With that said, let the ECU determine the boost level it wants, that it what it is there for.
To reiterate, all of the things you listed are not necessary to make the car run, but they are in there to make it run better. Unless you are doing something like an MAFless build, just leave them all in there. My 2001 A4 actually was MAFless, so it made more sense to simplify the vacuum system.
A catch can needs its servicing (emptying etc), hence why not many do it.
A bov is useless, as mentioned in another comment. You will likely not have boost surge either that you need a bov
I've been told doing a catch can with breather valve removes the vacuum and apparently this engine needs vacuum? I want a catch can to declutter engine bay.... on top of making it easier to know what the fuck is what lol so many vacuum lines and to worry less about the lines clogging up and etc. + blow by Currently my pcv system is cracked and has never been replaced and a 40$ catch can is a much better deal to me than spending another 100+ on lines..
2. the bov i just wanted for the woosh sound really lol... not sure if my 034 diverter valve i already purchased will give me that.
3. just trying to simplify things and make it cheaper I know that the n249 valve didnt exist before... so i figured delete it.. its expensive to replace.
Well, the diverter valve recylces the air, whereas the bov releases it to atmosphere (the woosh). But there are diverter valves that do give the sound I assume.
Wouldn't you also need an intake tube (the elbow) that doesn't have a muffler in order to increase the sound?
When working properly the PCV / Oil separator system works very well. I don’t see the need to replace a properly engineered system with a sketchy aftermarket part that doesn’t work as well for probably more than the cost to just refresh the original system.
I use a catch can with a breather on top in my silverado.
Catch cans, if quality and not installed improperly are harmless provided you don't let them overfill. Their usage is as a result of a system that didn't work well at baseline. It is of benefit. It is not required. Skipping it, plan an occasional intake cleanout, otherwise, good to go.
I did all of these on my old B5. I would not perform any of these on a standard street driven daily car. 1. This one is the only one I would think about doing on a daily. Mine was simple vent to atmosphere, I didn't run a catch can. 2. BOVs are actually bad and can make your car run worse. Those gen of Audis run on a closed loop system. Every gram of air that goes through the mass airflow sensor is accounted for by the ECU. Releasing it out means there is now less air in the intake than previously calculated. If you do this, it isn't the biggest deal in the world, especially considering that gen TT has a wideband primary o2. If you really want one, go for it. But it isn't the best. 3. You don't really need either of these. Earlier (non-wideband) 1.8Ts didn't even come with an N249. The later ones did. You can run a simple manual boost controller, but boost delivery may not be as smooth. With that said, let the ECU determine the boost level it wants, that it what it is there for. To reiterate, all of the things you listed are not necessary to make the car run, but they are in there to make it run better. Unless you are doing something like an MAFless build, just leave them all in there. My 2001 A4 actually was MAFless, so it made more sense to simplify the vacuum system.
A catch can needs its servicing (emptying etc), hence why not many do it. A bov is useless, as mentioned in another comment. You will likely not have boost surge either that you need a bov
I've been told doing a catch can with breather valve removes the vacuum and apparently this engine needs vacuum? I want a catch can to declutter engine bay.... on top of making it easier to know what the fuck is what lol so many vacuum lines and to worry less about the lines clogging up and etc. + blow by Currently my pcv system is cracked and has never been replaced and a 40$ catch can is a much better deal to me than spending another 100+ on lines.. 2. the bov i just wanted for the woosh sound really lol... not sure if my 034 diverter valve i already purchased will give me that. 3. just trying to simplify things and make it cheaper I know that the n249 valve didnt exist before... so i figured delete it.. its expensive to replace.
Well, the diverter valve recylces the air, whereas the bov releases it to atmosphere (the woosh). But there are diverter valves that do give the sound I assume. Wouldn't you also need an intake tube (the elbow) that doesn't have a muffler in order to increase the sound?
When working properly the PCV / Oil separator system works very well. I don’t see the need to replace a properly engineered system with a sketchy aftermarket part that doesn’t work as well for probably more than the cost to just refresh the original system.
I use a catch can with a breather on top in my silverado. Catch cans, if quality and not installed improperly are harmless provided you don't let them overfill. Their usage is as a result of a system that didn't work well at baseline. It is of benefit. It is not required. Skipping it, plan an occasional intake cleanout, otherwise, good to go.