PCV deletion / Catchtank installation

[Rusty]

You need the gearbox pl,ug for the smaller stuff, sump plug is 26mm, drain is about 18 I think.

The ABY cam cover is 14mm outlet, I think the 3B is smaller.

[newsh]

One interesting thing is across the Pond the US guys are saying do not use the nipple on the rear of the cam cover for a catch tank as it fills with oil under hard acceleration.

Yes interesting, my catch tank filled twice at CC last year. I wasn't sure whether it was coming up the crank tube or off the cam cover but I suspected the latter, its only ever done it at the track AFAIK and I've got a plan to change the tubes for bigger ones. I guess it points to the reason the original cam cover tube goes down and tees into the bottom of the crankcase tube, so if it fills with oil it will drain downwards.. I might just go back to a T arrangement or fit a new camcover nipple on the top of the cover.

[Rusty]

I'd have guessed crank vent on yours that time, right hand bends at high g and lots of throttle, crank case vent is on the side that would see any oil surge during cornering. What bore is 3B head vent and where was it plumbed in John? I thought you were running a Newsh special T piece? Shame the battery is in the space where a nice tank would fit, best stick it in the boot, who needs a spare wheel

[JP]

Yes interesting, my catch tank filled twice at CC last year. I wasn't sure whether it was coming up the crank tube or off the cam cover but I suspected the latter, its only ever done it at the track AFAIK and I've got a plan to change the tubes for bigger ones. I guess it points to the reason the original cam cover tube goes down and tees into the bottom of the crankcase tube, so if it fills with oil it will drain downwards.. I might just go back to a T arrangement or fit a new camcover nipple on the top of the cover.

I've tried both ways with the t down to sump and direct, I've tried 19mm of the crankcase and 28mm. All of them fill the catch tank when driving the car hard. I played about with different driving styles and discovered the catch tank filled up incredibly quick with lots of hard cornering and hard launches. Motorway redline shifting barely filled the tank up.
Running the oil level closer to the minimum mark on the dipstick also lessened the amount the catch tank filled by.
Tried breathing to atmosphere and back into the intake tract. Neither made a difference if anything breathing to atmosphere made it slightly worse as the car started smoking at idle due to crankcase pressure build up causing the turbo exhaust seal to pass oil from poor oil return due to increased crankcase pressure as I've deleted the PCV valve which originally allowed breathing directly into the intake plenumb at idle to eliminate this problem on factory cars.
Pointing to the fact that it is from oil surge around the crankcase breather area causing the problem. In effect blocking the crankcase breather system forcing the oil out under crankcase pressure.

So I've now got a new setup planned to give as many counteractive measures as possible.
Basically rear of rocker cover t's down to crankcase and has a 19mm going to an oil separator. There is an extra 16mm coming of the rocker cover done through a welded on breather box like the 1.8t rocker covers have using the original rocker cover as a baffle, This also goes to the cyclone style oil separator.
This then has a permanent 16mm drain back to sump. The outlet of the separator is also 19mm and goes to a very intricately baffled double catch tank design that Rusty is kindly making up for me. The outlet of this goes back into the induction pipe before the turbo fed in from underneath the induction pipe.

From 2 months of experimentation and numerous costly hose combination's it's the only configuration I could get to work successfully based on a proven system used on the Jap drift cars that suffer enormously from oil surge. Each modification has worked a treat and the new catch tank that will arrive hopefully at the end of the month will be the icing on the cake instead of the makeshift setups I've welded up during the experimentation stage.

What one has to remember is the following about an engine. It doesn't matter how good your clearances are how good your rings seals and how perfect everything is. In order for your engine to operate there needs to be gaps which are sealed by oil on the inside of the guides and bores. As you increase combustion temperatures by an increase in rpm and/or boost the oil on the surface at the top of the bores is burned away and so is the oil around the valve stem from heat transference. This results in x amount of cylinder leakage into the cylinder head through the guides and stem seals and into the crankcase past the rings.
Now if you imagine that the amount of combustion gases that seep past the rings and seals is say of a value of 'x' at 1000rpm at 7000rpm not only is the value now 7x but also exponentially increased relative to positive boost pressure which is in effect raising your compression ratio higher up in the rpm range.

These gases that now pressurize the crankcase need venting for 3 main reasons,

1) A pressurized crankcase causes ring failure on the oil control ring (2nd ring) as this is designed to work under directional pressure from the combustion cycle. If you pressurize the crankcase you may aswell install the ring upside down and kiss your engine goodbye as it will smoke under any sort of load.

2) You are physically adding resistance to the downward stroke of your pistons as you are acting against the pressure build up in the crankcase, like punching through air and then suddenly having to punch through water robbing your rotating assembly of valuable energy and ultimately lost crank tq.

3) The pressure has got to find it's way out in the form of leaking rocker cover gaskets camshaft and crankshaft seals, like the annoying whistle you get from a worn rear crank seal when you crank the boost up on a 180K mile engine.

So our ultimate aim is now to reduce crankcase pressure by venting. In an ideal world your crankcase wants to be equal to or less than atmospheric pressure which means your rotating assembly has free motion.
If you can actually achieve a vacuum you will gain hp by freeing up resistance to the rotating assembly, pretty much the same effect that forces have in space where there is total vacuum.
On a naturally aspirated motor this can be achieved by venting to atmosphere with small bore sizes as they increase to 90mm+ this becomes more difficult. On a FI motor this becomes even more difficult as the amount of gases forced into the crankcase require now much bigger diameter pipework in order to stabilize to atmospheric pressure. So the easiest resolve is to apply vacuum to the crankcase by various means. Each of these breathing methods has there own pro's and con's, all of them I've used or experimented with at one point on various motors.

a) plumb back into the intake
pro's - the more air the engine ingests the more vacuum it applies on the breather system to help scavenge the gases out the crankcase
con's - oil vapours re enter the intake and degrade air quality causing a decline in power.
Solution - intricate baffling system to eliminate maximum oil vapours from re entering intake tract

b) breath to atmosphere
pro's - eliminates any event of oil vapours re entering the intake tract
con's - high boost high rpm engines are very unlikely to be vented properly using standard plumbing
Solution - run maximum diameter pipes with extra venting points from rocker cover to try and balance pressure

c) one way PCV breathing system into exhaust pipework
Pro's - very effective way of scavenging from the crankcase using exhaust flow to siphon out pressure.
Con's - although extremely effective on naturally aspirated application the existing systems on the open market are no good for FI application as the PCV valves in the kits cannot withstand the temperatures reached by FI motors exhaust systems leading to failure and exhaust gases pressurizing the crankcase instead.
Solution - none for FI engines

d) Dry sump oil system
Pro's - run a 4 or 5 stage pump using the extra scavenging stages to pull vacuum on crankcase and rocker cover.
Con's - very expensive method to implicate on the average car

e) Vacuum pump
Pro's - belt driven vacuum pumps that run of the crank much like a dry sump pump but specifically only for pulling crankcase vacuum, cheaper and easier to implement than a dry sump system as you retain original oil pump setup.
Con's - potential space issues and pulley setup configurations for the I5 engines.

For the I5 engine I've stayed with 'a' for being most cost effective solution for maximum benefit.

[Rusty]

I was thinking about an intermediate expansion tank between the outlet and tank, it would provide the substantial reservoir for any surge. This could take the form of a swirl pot with sump return or just a 0.5 litre bulb.

[A80Avant]

i use the a solution and i get only vapours in the intake track(venting in OEM position in front of turbo). My tank is more or less empty since i put it there and there are no signs of oil residue in the turbo inlet tract since i fitted it. quite a bit of gung very slowly filling up the tank,but minimal.
Rocker cover hasnt leaked or soaked for a while now.

however, i dont go WOT all the time and havent been on a track.

My next setup would be to take the both tubes that go to the rocker cover and put to the tank.I presume it may work more efficiently.Essentially only fumes are going back to the intake and to be honest, how low can those make the AF mixture? will it kill 10hp? i can live with that

[JP]

I was thinking about an intermediate expansion tank between the outlet and tank, it would provide the substantial reservoir for any surge. This could take the form of a swirl pot with sump return or just a 0.5 litre bulb.

pretty much what the oil separator is doing in mine to take away the initial surge, draining into the fumoto valve, passing on only mist to the catch tank. I'll email you some dodgy scribbles showing you what I did with mine real easy to make.

[Jamo]

I've tried both ways with the t down to sump and direct, I've tried 19mm of the crankcase and 28mm. All of them fill the catch tank when driving the car hard. I played about with different driving styles and discovered the catch tank filled up incredibly quick with lots of hard cornering and hard launches. Motorway redline shifting barely filled the tank up.
Running the oil level closer to the minimum mark on the dipstick also lessened the amount the catch tank filled by.
Tried breathing to atmosphere and back into the intake tract. Neither made a difference if anything breathing to atmosphere made it slightly worse as the car started smoking at idle due to crankcase pressure build up causing the turbo exhaust seal to pass oil from poor oil return due to increased crankcase pressure as I've deleted the PCV valve which originally allowed breathing directly into the intake plenumb at idle to eliminate this problem on factory cars.
Pointing to the fact that it is from oil surge around the crankcase breather area causing the problem. In effect blocking the crankcase breather system forcing the oil out under crankcase pressure.

So I've now got a new setup planned to give as many counteractive measures as possible.
Basically rear of rocker cover t's down to crankcase and has a 19mm going to an oil separator. There is an extra 16mm coming of the rocker cover done through a welded on breather box like the 1.8t rocker covers have using the original rocker cover as a baffle, This also goes to the cyclone style oil separator.
This then has a permanent 16mm drain back to sump. The outlet of the separator is also 19mm and goes to a very intricately baffled double catch tank design that Rusty is kindly making up for me. The outlet of this goes back into the induction pipe before the turbo fed in from underneath the induction pipe.

From 2 months of experimentation and numerous costly hose combination's it's the only configuration I could get to work successfully based on a proven system used on the Jap drift cars that suffer enormously from oil surge. Each modification has worked a treat and the new catch tank that will arrive hopefully at the end of the month will be the icing on the cake instead of the makeshift setups I've welded up during the experimentation stage.

What one has to remember is the following about an engine. It doesn't matter how good your clearances are how good your rings seals and how perfect everything is. In order for your engine to operate there needs to be gaps which are sealed by oil on the inside of the guides and bores. As you increase combustion temperatures by an increase in rpm and/or boost the oil on the surface at the top of the bores is burned away and so is the oil around the valve stem from heat transference. This results in x amount of cylinder leakage into the cylinder head through the guides and stem seals and into the crankcase past the rings.
Now if you imagine that the amount of combustion gases that seep past the rings and seals is say of a value of 'x' at 1000rpm at 7000rpm not only is the value now 7x but also exponentially increased relative to positive boost pressure which is in effect raising your compression ratio higher up in the rpm range.

These gases that now pressurize the crankcase need venting for 3 main reasons,

1) A pressurized crankcase causes ring failure on the oil control ring (2nd ring) as this is designed to work under directional pressure from the combustion cycle. If you pressurize the crankcase you may aswell install the ring upside down and kiss your engine goodbye as it will smoke under any sort of load.

2) You are physically adding resistance to the downward stroke of your pistons as you are acting against the pressure build up in the crankcase, like punching through air and then suddenly having to punch through water robbing your rotating assembly of valuable energy and ultimately lost crank tq.

3) The pressure has got to find it's way out in the form of leaking rocker cover gaskets camshaft and crankshaft seals, like the annoying whistle you get from a worn rear crank seal when you crank the boost up on a 180K mile engine.

So our ultimate aim is now to reduce crankcase pressure by venting. In an ideal world your crankcase wants to be equal to or less than atmospheric pressure which means your rotating assembly has free motion.
If you can actually achieve a vacuum you will gain hp by freeing up resistance to the rotating assembly, pretty much the same effect that forces have in space where there is total vacuum.
On a naturally aspirated motor this can be achieved by venting to atmosphere with small bore sizes as they increase to 90mm+ this becomes more difficult. On a FI motor this becomes even more difficult as the amount of gases forced into the crankcase require now much bigger diameter pipework in order to stabilize to atmospheric pressure. So the easiest resolve is to apply vacuum to the crankcase by various means. Each of these breathing methods has there own pro's and con's, all of them I've used or experimented with at one point on various motors.

a) plumb back into the intake
pro's - the more air the engine ingests the more vacuum it applies on the breather system to help scavenge the gases out the crankcase
con's - oil vapours re enter the intake and degrade air quality causing a decline in power.
Solution - intricate baffling system to eliminate maximum oil vapours from re entering intake tract

b) breath to atmosphere
pro's - eliminates any event of oil vapours re entering the intake tract
con's - high boost high rpm engines are very unlikely to be vented properly using standard plumbing
Solution - run maximum diameter pipes with extra venting points from rocker cover to try and balance pressure

c) one way PCV breathing system into exhaust pipework
Pro's - very effective way of scavenging from the crankcase using exhaust flow to siphon out pressure.
Con's - although extremely effective on naturally aspirated application the existing systems on the open market are no good for FI application as the PCV valves in the kits cannot withstand the temperatures reached by FI motors exhaust systems leading to failure and exhaust gases pressurizing the crankcase instead.
Solution - none for FI engines

d) Dry sump oil system
Pro's - run a 4 or 5 stage pump using the extra scavenging stages to pull vacuum on crankcase and rocker cover.
Con's - very expensive method to implicate on the average car

e) Vacuum pump
Pro's - belt driven vacuum pumps that run of the crank much like a dry sump pump but specifically only for pulling crankcase vacuum, cheaper and easier to implement than a dry sump system as you retain original oil pump setup.
Con's - potential space issues and pulley setup configurations for the I5 engines.

For the I5 engine I've stayed with 'a' for being most cost effective solution for maximum benefit.

Interesting I hadn't seen this post after my motorgeek one, so it's oil separator then a catch tank then inlet.

Right blueprint confirmed

[GazzaG60]

i dont have a tank and dont fill the engine bay with oil either.

id go n75 for the flutters. quality boost controllers save headaches.

[JP]

Interesting I hadn't seen this post after my motorgeek one, so it's oil separator then a catch tank then inlet.

Right blueprint confirmed

Yep pretty much, I have since found that catch tank outlet into top of the turbo induction hose is tidier and makes no difference to the overal performance if anything it stops moisture sitting in the bottom of the elbow like when it is plumbed from underneath.

Didn't realise you hadn't seen this post, guess it saves me having to go into too much detail on the build thread for you. If you need clarification on anything just pm me.

Cheers.

[Sleeper_Avant]

getting back to my cosworth days, we always suffered with smokey motors with big boost.

3 port breather (cam cover, block oil drain) worked well

but i always breathed from
cam cover x2
block x2
back to sump
catch tank before oil seperator

will be doing the same on my A4 tomorow before the head goes back on

Non Audi tuning on an Audi........ i should be shot who votes it wont work lol

Sarcasm is the lowest form of wit apparently.....i like it!

[A80Avant]

here is my final setup



separator on the top right(black),
2nd tank in the middle wrapped in lava mat, returning to the turbo

[fundahl]

Very nice! Do you log crankcase pressure?

[krzysztofkabaj]

One question. Currently I'm rebuilding PCV circuit from a scratch to new one with can and return line to oil sump. Everything solved besides N80 valve and charcoal filter of fuel tank vent. Mentioned both will be deleted but what to do next with fuel tank vent ?.

[popdemonic]

One question. Currently I'm rebuilding PCV circuit from a scratch to new one with can and return line to oil sump. Everything solved besides N80 valve and charcoal filter of fuel tank vent. Mentioned both will be deleted but what to do next with fuel tank vent ?.

you just connect the n80 directly under the intake manifold.
I'm going to do mine pcv upgrade soon but i want tp keep the vacuum
to pull the gas fumes under negative pressure(on idle).