Oil Breather System - Upgrade ? Help Please !

[macspring]

Hi all,

Most questions have been asked on this forum, but I 'm not sure if the ones below have, so here goes. BTW shoot me down in flames if either have, but post the link first.

I wanted to upgrade the oil breather system on my S2 Avant, as part of a general upgrade of most bits.

What I have in mind is to remove all of the factory oil breather re-circulation apparatus, and replace it with a catch tank system.

The new oil breather catch tank would have two inlets on the side of the tank, ( the tank will be roughly similar in size to a 500 ml can of beer ), one inlet will come from the top of the engine and the second inlet will come from the side of the engine block.

There will be an outlet point at the base of the catch tank to allow the liquid oil drain back into the sump or a second tank mounted lower down that can be emptied easily as the need arises.

All of the above is is very straight forward, the difficult part, ( for me anyway ), is the breather out at the top of the oil catch tank, normally this just vents to the atmosphere, via a small filter.

I want to have this outlet go to the exhaust pipe to create negative pressure in the engine block, ( as suggested, I think, in a David Vizard's book about tuning Ford Pinto engines ). The article that I read put forward the idea that by having this negative pressure inside the engine block that it increased power.

Where the pipe joins into the exhaust pipe is the bit I wanted to get someone's suggestion as to where I might source a suitable stainless steel "Y" shaped piece to let into the exhaust which is to be made up for the car anyway as part of the upgrades.

I'm not good enough on the computer to be able to post up a representative drawing of the "Y" shaped pipe, but the main exhaust would naturally be larger than the one from the top of the oil breather catch tank. As part of this piece of pipe-work it would have a shield inside the main section of the exhaust pipe to prevent the exhaust from the engine interferring with the vapour from the top vent of the oil breather catch tank. Additionally it should also have a one way valve in it to prevent the exhust from being able to go back towards the oil breather catch tank.

I hope you can understand the principle and the question ? !.

I had thought that this type of thing might be available in the custom car "world", but have not found anyone who makes such an item off the shelf or on a bespoke basis.

One last separate question what is the principle behind / purpose of / advantage for having second much smaller exaust pipe at the rear of the car that is fed by the dump or blow valve from the turbo? i.e. a screamer pipe?

Thanks in advance for any suggestions anyone has on either of these two queries.

Kind regards.

[topsparky]

check out s2 daves latest post
seems corey is doing a twin catch tank
system

[macspring]

@ topsparky

Thanks, you're up late also.

Regards.

[newsh]

This has indeed been covered in depth in the past. The breather system is known as the PCV system, Positive Crankcase Ventilation, try a search you will find drawings of the Y pipe you mention and a few ways to accomplish the catch tank / drain to sump, some from OEM Audi parts. The stock PCV system is designed to apply vacuum to the crankcase, from the IM at idle and off throttle, switching to the MAF hose when in boost.
I've been down the catch tank route and gone back to the PCV as I didn't like the smell of fumes, I never got the Y pipe to exhaust organised though.

You'll find posts about the separate WG pipe too, a couple of people have done this.

[Greg_S]

Also with the y pipe to the exhaust if you look through dougs project thread he did connect up to the exhaust to get negative pressure.

[Mark Halligan]

I want to have this outlet go to the exhaust pipe to create negative pressure in the engine block, ( as suggested, I think, in a David Vizard's book about tuning Ford Pinto engines ). The article that I read put forward the idea that by having this negative pressure inside the engine block that it increased power.

David

You are right about negative pressure when applied to the crankcase making more power, it does this primarily by increasing ring seal.

But in my recent experience you wont generate enough vacuum by using tapping into the downpipe to generate negative pressure...well not if you have a full exhaust system on your car.

Here is how I came to this conclusion……the oil control rings I am using with my Total Seal ring pack are low tension, they are good for making power because they create less friction in the bore, but when the engine has high manifold vacuum at idle, they allow some oil to sneak past them. This can be cured by creating a state of vacuum in the crankcase.

In order to get around this problem I have had to change my catch tank setup to a closed system, similar'ish to the standard PCV set up, so that it generates vacuum in the crankcase at idle and this has solved my problem. I wont go into the detail of how I did it, but it does look a bit wacky races

Before I arrived at my current setup and solved the problem, I did a lot of fooking about and experimenting with different alternative setups, and in doing so one of the first things I tried was the downpipe method.

I also installed a vacuum gauge to the breather system to measure crankcase vacuum to see if it worked.

I had thought that this type of thing might be available in the custom car "world", but have not found anyone who makes such an item off the shelf or on a bespoke basis.

This stuff is available but not over here. The American racers generate crankcase vacuum in their engines regularly to release more power.

One way (the budget method LOL) is via the venturi method you have mentioned but instead of fitting it to a full exhaust system with all of the back pressure created by the silencers in that system, the US racers mainly mount the venturi straight into an open header system with no back pressure. This allows enough of a pressure differential to suck out the crankcase gases/blowby.

These kits are available in the US and I fitted one of these: http://www.afabcorp.com/AFCO_Dynatec...ory_Code=pan-e

Along with this check valve to prevent exhaust back pressure traveling back up and into the breather system:http://store.summitracing.com/partde...5&autoview=sku

Moroso did do a full kit including the inserts and check valves but I can't find the link to it now.

I mounted these into the bottom of my 4” downpipe and measured the vacuum it made……the needle didn’t move LOL.

In my experience when using a full exhaust system with all of its back pressure this wont generate enough vacuum to be of any benefit, either at idle, cruise or when caning it.

I recently disconnected the breather system from the downpipe as there was too much pressure in the exhaust system at full throttle to allow the catchtank to vent into the DP.

I am not saying that this doesn’t work, just that it hasn’t worked for me.

IMHO The only way to effectively evacuate a wet sumped crankcase of blowby under full power when using a full exhaust system (with all its back pressure) and gain the power benefits of the vacuum created is to fit a vacuum pump like these:

http://www.moroso.com/catalog/catego...?catcode=17200

http://www.starvacuumpumps.com/

Although these have are built for racing and have a limited life between rebuilds.

This Company (GZ Motorsports) markets a pump that can be used for street use but it would need regular maintenance.

http://www.gzmotorsports.com/street-pump-kits.html

One other point worth noting is that if you pull (again in my experience on the I5 motor whilst experimenting) more than about 8 – 10 inches of Hg vacuum in the crankcase the standard crank seals will lift (the rear seal first) and the engine squeals loudly as air (and possibly dirt) is sucked past the seals into the crankcase.

At idle using the system I have at the moment, I am pulling 8 inches Hg in the crankcase and apart from the occasional chirp this seems to be about right.

I did look into getting a motorsport crank seal from Race-Tec which would hold more vacuum, this is the reply I received:

Dear Mark

“As you may be aware, Race-Tec specialises in the bespoke manufacture high performance seals for the Motorsport Industry. I have looked through our seal availability, the only seal that I can find to meet with your exact requirements is our RT 22730 [drawing attached] = 85 x 105 x 9mm. This is a PL 6 style of seal and is tested to maintain vacuum well above 20" of Mercury. The seal was originally designed for an Audi V8 Le Mans engine.

What type of racing are you involved in?

Cost

RT 22730 x 10 = £85.67 each

Ex-works Chandlers Ford

For your general information I have attached our data sheet on crankshaft seals.

If you are interested in the RT 22730, please get back to me.”

Race-Tec were very helpful and replied very quickly and I would have bought one but they had none on the shelf and the minimum order was for ten……group buy anyone

So to sum up, the downpipe method didn't work for me

I reckon that the ideal set up for power would be to use a vacuum pump to generate negative pressure in the crankcase whilst on boost as the racers in the US do. Out of the choices available maybe that street/strip vacuum pump from GZ Motorsports offers the best reliability?

If you so some searches on forums like Speed Talk there is a lot more info.

Sorry for the long post, but I HTH

Cheers

[S2central.net]

Brilliant stuff Mark... How come you get the BTDT first on just about all the exciting stuff. Gotta love that reply from Race-Tec when they twig they have a potential customer specifying such exotica.

Like your thinking and analysis on this - you have done your homework as usual

I was gonna just go for a decent cyclone tank with the option to drain oil back to the sump, and vent the remainder of fumes back to MAF hose as per factory PCV system if its too smelly venting to atmosphere. Didn't you have yours venting at the inner wing near the airbox at one stage - was that a bit whiffy ?

Paul

[newsh]

Sorry for the long post, but I HTH

Cheers

[macspring]

As always quick and comprehensive replies, thanks to all.

Mark, thanks for your extensive reply and taking the time to type / share your experiences -

I looked at the links / sites, but after the hassle and effort you went to to verify the optimum arrangement, I think at this stage, I’ll stop trying to be too clever with a vacuum for the vent pipe of the oil breather catch tank -

I’m going to see what Corey has in mind for DaveS2’s car, as per Topsparky’s post.

I think I might try - http://jeffdaigle.com/prevent/proven...er-install.pdf - for the breather on my Mk 2 Jetta 1.8 T. And also the family 1.9 TDI Touran - http://www.republicsales.com/MANN/Provent_Brochure.pdf.

Newsh and Greg S thanks also -

Kind regards.

[Jamo]

Brilliant stuff Mark... How come you get the BTDT first on just about all the exciting stuff. Gotta love that reply from Race-Tec when they twig they have a potential customer specifying such exotica.

Like your thinking and analysis on this - you have done your homework as usual

I was gonna just go for a decent cyclone tank with the option to drain oil back to the sump, and vent the remainder of fumes back to MAF hose as per factory PCV system if its too smelly venting to atmosphere. Didn't you have yours venting at the inner wing near the airbox at one stage - was that a bit whiffy ?

Paul

Saw this in real life on friday night, what a complex system! Mark is akin to Doc from Back to the future

[Mark Halligan]

LOL Thank you Jamo

Now a stainless steel bodied, fusion powered S2 would be something, especially if you could fuel it on old banana skins...

Didn't you have yours venting at the inner wing near the airbox at one stage - was that a bit whiffy ?

Paul

yes it was smelly, but I have it doing this again with the new engine and its not so bad as I don't get anywhere near as much blowby with this one.

Cheers

[Jonas_R]

Hi,

My system is wenting by the right front wheel and I have no fumes in the car. Used a sniffer to test it

[DJones]

Very good read, well done Mark. Never even considered the vacuum situation.

I made a two bottle version as below, the first bottle goes back to the sump and the second bottle vents to atmosphere. The second picture shows the holes i cut at the back of the bonnet, mainly for heat but it takes the smell away to.

[DJones]

........

[Jeffer]

Mark, Nice research man. Count me in for the group buy! If that will ever happen