Engine block breather upgrade?

[HPmuirt]

Greetings,

As those at ADI this year will know, my breather system took exception to the track abuse and decided to spray oil everywhere as well as pumping quite a lot into my intake system

Whilst looking at catch tanks and other upgrades, I thought I should change the engine block breather (the fat one down by the bottom of the dip stick) as I gather they can get blocked up over time with carbonised oil etc.

Has any one looked at better versions/upgrades etc or do most folks just stick with the OEM part?

Cheers n

Si

[jade]

Greetings,

As those at ADI this year will know, my breather system took exception to the track abuse and decided to spray oil everywhere as well as pumping quite a lot into my intake system

Whilst looking at catch tanks and other upgrades, I thought I should change the engine block breather (the fat one down by the bottom of the dip stick) as I gather they can get blocked up over time with carbonised oil etc.

Has any one looked at better versions/upgrades etc or do most folks just stick with the OEM part?

Cheers n

Si

I removed the pipe and use a 25mm to 15mm elbow samco, to my catch tank

[S2central.net]

I dunno if its wise to remove the PCV valve as it controls crankcase pressure... Pretty sure I read somewhere that you can have issues with idle stability if their is absolutely no backpressure in the crankcase - fine for a race/rally car - maybe not for a road car. IIRC the valve opens with increasing crankcase pressure to allow more of it to escape --> into the IM on vacuum and the suction side of MAF hose when on boost --> the latter is what often causes the raging oil mist to blow into the turbo - mess up AFR, contaminate your air, raise inlet temps, collect oil in your intercooler and all manner of other ills.

The more I think about - the more I want to get rid of the factory setup on mine. Rusty is well up on these things so he is better placed to advise on the pros and cons of various catch / return systems. I think most folk just use the stock valve with a catch tank - but I could be wrong.

Cheers,

Paul

[s2driveruk]

Si, you're not alone with PCV problems, mine was literally dripping in oil after ADI as was the complete intake path. I took off my pcv valve and it looked absolutely fine and cleaned easily with carb cleaner. I've not seen any alternatives so might be better to just clean up the original or stump up a tenner for a new one...

pretty sure my car was running crap because of the amount of oil feckin up the inlet temps. yet to take the I/c off to find out how much is pooled in there

[Tonks4x4]

Is it worth while seeing if there is any way of fitting a drain off on the IC as even with a good catch tank it can still build up over time as it's the lowest point? Just an idea

[Rusty]

Most PCV valves seem to do nothing at all as they're screwed, mine might well have been a 90 deg bend for all the use it did. I've not run one with my catch tank and haven't noticed any differences in idle. Same for removing and blocking the N80 pipework to the IM, no change. I can't promise that's the same for all and I know RWD19T has had some smoking on idle due to no 'suction' on the breather system - his car is somewhat modified though and now has the mother of all catch tanks

For a road car you can just fit a catch tank in the system - get a proper one though and proper doesn't mean shiney Chinese Eb_y special TBH less than RS2 spec it'll catch more water than oil when used on the road all year round - even my more than spirited driving, launches, 2nd and 3rd gear WOT runs didn't trouble it one bit - so avoid a wet sump return here. It's cornering that puts any small amount of oil into the tank - right handers taken at WOT. The tank will catch most of what little oil there is but it's really very little.

Above RS2 spec and the oil vapour has enough energy for the catch tank to do its thing nicely so well worth it there - RS2 spec really is as high as the stock system can cope with on the road.

GT30+ and I'd suggest a swirl pot or catch tank with wet sump return (below the oil level) on a road car too, otherwise you might get a nasty suprise when 1L of oil is in the tank and not the car. This can happen under acceleration due to the higher g forces and crank case pressures.

On track it's a different story (as a few found out at ADI, including me with my catch tank). Right hand bends and application of WOT thereof mean that the oil is forced up the tubes via the cornering foces as well as the crank case pressure and so a catch tank is essential on any track S2 for this reason alone (sorry to use bold but it's now proven), preferably a well designed one rather than an Eb_y special but something is better than nothing I guess... I found that with my tank attached to the stock head/block combo pipe with 19mm pipe, I was putting 100-150ml / session into my tank... that's with just ~300bhp. Without the tank that's got to be 50-100mm into the breather inlet... turbo... IC... etc. (s2driveruk )

The only substitute for a tank is a swirl pot, correctly designed and fitted, which uses a wet sump return. It will have similar condensation issues though so be warned if you fit a sump return on a road car of modest output. You can also wet sump return a catch tank but for the reasons above, it's not worth it on a road car RS2 spec or less. A swirl pot does a similar job as a catch tank, just in a different way - a swirl pot does not collect the oil, it has to drain somewhere for the system to work properly - hence the wet sump return.

For over RS2 spec, you need both a swirl pot and catch tank for a track car with a wet sump return and maybe a larger head breather. Anything less and the £5k you've sunk into an engine and turbo and map and etc. etc. and it's all at risk for not spending 5% more.

For the rest of us, larger pipework is the key IMO. I'm working on a faux swirl pot that will work on road/track cars up to RS2 spec. This will use 30mm pipe from the crank breather to the swirl pot and sleeve the head breather to 19mm for better breathing. This will rely on the larger pipe allowing any oil to drain to the sump while maintaining a clear airway. It replaces the current 15mm pipework that's stock on the S2 (this uses the same method of breathing but is ~25% of the area). The 'swirl pot' also provides a method of slowing the breather vapours (helping deposition and condensation of the oil) and thus helps to stop most of the oil reaching the tank in the first place - leaving it in the engine! The 'swirl pot' oulet then feeds to a tank that catches anything that's got past. If it's empty then all the better IMO as the oil remains in the engine. Better to not have any oil in the tank than the tank catch it all IMO.

Remember, everything the tank collects isn't in the sump. @ 150ml / session, that's ~10% of the engine's oil / half day... 20% / 6 session track day... Not ideal when the S2 needs to be brimmed to keep the head happy anyway (remember that ticking top end after a thrash anyone )

Anyway, lots of info there. Happy to help as I've spent time and money looking into this and thanks to some chats with RWD19T and Newsh, I'm getting a better picture of what's going on all the time.

[terrybullwon]

It wont help on track having the breather at the rear of the cam case on track your oil will want to be coming out of there. You need to weld a fitting or a nipple to the top of the cam cover

[terrybullwon]

[Rusty]

Need to do some testing here (have you done any James?) as I've not quantified the amount of oil that goes from the head to the block via the little pipe. A simple test to do with a bottle and some pipe...

By maintaining this circuit, the situation is not worsened on a stock car, as the oil will return to the sump. With a separate head feed to the tank, it could be a lot worse. That said, the 3B has a smaller outlet on the head and this could prove an issue with blockages.

A nice way to do it (if packaging doesn't allow a modified head breather) is to feed separately to the swirl pot and that in turn to the sump.

Will have to see if I can experiment with this one...

[terrybullwon]

Need to do some testing here (have you done any James?)

Not personally but audi sport did it for me...........





Where else would you get all your oil from after your track session?

[Jamo]

I posted on that a while back, there's an American member who's proven that the vent on the back becomes a dump tube under hard acceleration

[terrybullwon]

I posted on that a while back, there's an American member who's proven that the vent on the back becomes a dump tube under hard acceleration

I thought i dreamt that up, i tried to find your post but could not

The force is strong with this one

[Rusty]

Where else would you get all your oil from after your track session?

Not so fast James. Don't forget that the ABY dumps that head breather into the sump so it's not a direct feed to the tank and would need to be forced upwards by the crank case vent. 3B is slightly different IIRC.

I'll do a little research for launches and see what happens...

[andy10v]

I can confirm that a stock 3b empties a large amount of oil out of the breather on the rear of the head whenever driven enthusiastically, unfortunately I never measured the mileage/oil consumption but it was very noticeable, drive the car normally and no oil was emptied out, drive it hard for 5 min, go look under the bonnet and the hose would be full of oil.

I want something like the breathers posted above, however as a temporary measure I am going to make something like this and see what the effect is when the rear head breather is blocked off.



Are the head and crankcase linked? I have seen a 20v with 3 big breathers on the cam cover and no block vent, however don't know what block and what other modifications.

[andy10v]

Another solution, a couple of big breathers from the head, crankcase breather is vented to the head (in this case via the distributor port)

http://www.motorgeek.com/viewtopic.php?f=10&t=32530&hilit=breather

Wonder if that would work ghetto style; just drilling a few big holes in the valve cover and some kind of screw though fittings on fittings and venting crankcase>head>catch tank>atmosphere or intake. How much oil do cams throw off?

Mr terrybullwon, would you weld on fittings to a cam cover for a charge?