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tolsen

More power out of your Cdi - for free!

302 posts in this topic

Hi Tolsen,

About the possibility of your cyclonic air oil separator freezing....

When I have a weekend free I am going to attempt my version of an oil catch can.

I plan on using the QMR Stealth oil catch can.

http://www.qmrmotorsports.com/shop/product...roducts_id=3800

It's really large 3"*7" but that doesn't matter because I plan on mounting it outside the engine compartment, behind the bumper next to the exhaust manifold.

Hanging out in the cold, it will obviously freeze in the winter so I plan to wrap a copper tube around the outside of the can and solder it in place and then tap into the engines coolant system near the EGR Valve to route hot coolant around the can to keep it from freezing.

I realize heating the outside of the can will reduce the effectiveness of oil condensation inside the can, that's part of the reason for mounting it outside so that airflow will help to offset the coolant heating.

Regardless in the winter it will have to be drained before parking for the night, another reason to make it easily accessible.

So perhaps heating your cyclonic separator may be an idea.

By the way did you ever consider taking apart a Dyson Cyclonic Vacuum Cleaner to see if there are any bits that may work in your application?

CANMAN

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More like the cyclone vacuum configuration

post-95-1305596687_thumb.jpg

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How would the back pressure in a coalescing filter or oil separator be greater than in a regular catch tank? If the smart cdi's PCV is only on the top end, excess pressure would have to reverse-blow-by in order to "pump oil out the dipstick tube," wouldn't it? Seems unlikely that a small amount of back pressure (if indeed a filter would provide any) could do this.

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You would be surprised at the volume and gooey consistency of the condensate. It very quickly plugged every kind of filter that I tried. Even worse in the cold season.To push oil out the dipstick would take about 20 inches of water (perhaps double for oil?), which equals less than 1psi.I don't think you'd need to actually reverse the blow-by, just restrict its venting by a certain small amount.And all catch tanks I tried that had inlet/outlet smaller than 3/4" created back-pressure sufficient to do this.

Edited by bilgladstone

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Assuming dip stick tube is about 50 cm long, a crank case pressure of 4 kPa = 0.04 Bar = 0.58 PSI is sufficient to push the oil up to top of dip stick tube (use formula P = ρ x g x h).Pressure drop over a wet pneumatic coalescent filter is much higher typically 3 - 4 PSI with a max limit of 10 PSI.Ideally it is only oil that we want to filter out of the breather gasses. Steam must not be filtered out as it will cause crud and goo to build up in the filter or separator. There is also a small efficiency gain by returning steam to the inlet.My prototype cyclone separator seems to filter out oil mist and droplets extremely well. It won't filter out much oil vapour as running too hot for any oil vapour to condense.Coalescent filters are designed to filter out oil and water and will therefore get blocked by crud and goo.

Edited by tolsen

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Hmm... this is unfortunate because condensation of the hot oil vapour is the problem we are trying to defeat, no? It condenses and accumulates in the intake pipe or even in the intercooler.Would locating the separator further from the engine make it cooler and able to condense the vapours as well as spin out the droplets?

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Most oil in breather gasses on my Cdi is carried as oil mist and droplets. There should not be much oil vapour in a healthy running engine. Oil vapour is what you get when something goes wrong and engine overheats.

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Would any of the already-available cyclone separators work for our purpose?

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Probably - but where is the fun in that? ;):lol:

You can also buy aircraft ones - usually non cyclonic but fun -

Oil Separators

Even healthy engines have some blow-by (which creates oil vapour) - either from the rings or the valve seals - piston rings and seals need some clearance so they don't bind - they also need to vent water vapour that collects.

Cheers,

Cameron

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Thanks for that link Cameron.Some of those aircraft air oil separators may fit if barb sizes are right. The prices are sky high though and which will limit their popular appeal.Better fitting something specially designed for the Cdi. You should cobble something together from plumbing parts based on my conceptional design.

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I think I may have an OK idea here, cobbling parts together. From the valve cover, into the centrifuge, oil mist and droplets separate and drop to bottom outlet, which drains to a branch on the lower part of the dipstick tube. Upper port goes to the inlet on the TIK pipe.It's all small and contained enough that freezing or gelling of the emulsion should be a non-issue, and any water in the emulsion will either boil off in the sump or end up in the filter with other particulates in the slime.

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For a cyclone separator to work properly doesn't the bottom port have to be sealed?Wait, before I hit post, is that only if it there is a vacuum being drawin' through it?....reverting back to thinking it has to be sealed...

Edited by pinhead19

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It's just a centrifuge for this purpose. The misty gas comes in tangentially and as it hits the obstacle (the wall of the cylinder), the mist and droplets stick to the wall. The funnel shape enables the pooling oil emulsion to collect centrally and be drained.

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Here is a design that won't work especially in wintry conditions:

Posted Image

"Crankcase Vapors Condensor" US Pat. No 3664314 dated 23 May 1974.

This artwork is claimed to remove all condensates from crankcase breather gases including water.

I've been researcing US patent files for air oil separators. There are scores of Heath Robinson designs. This one is probably most peculiar of the lot.

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Once my sister's flight leaves in an hour or so I'll start scavenging parts around the house and in nearby shops. I'm quite sure I have 3/8" steel tubing and usable stainless odds and ends. I'll need to borrow my Neighbour's swaging (swedging, flaring) tool set, and get to BOC/Linde for fresh oxy-acetylene tanks. Mind you, the Victor torch hasn't been used in about 20 years, so maybe I need to tear it down for a cleaning and inspection... :D

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TK, in your opinion is a nozzle needed at the centrifuge's gas input to increase gas stream velocity or pressure? I would think it's already under enough pressure to induce swirling in such a tiny centrifuge.

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TK, in your opinion is a nozzle needed at the centrifuge's gas input to increase gas stream velocity or pressure? I would think it's already under enough pressure to induce swirling in such a tiny centrifuge.

It may work without a nozzle or reducer at input. There is one way to find out - try!

Remember the formula for centripetal acceleration?

Posted Image

Centripetal acceleration is inversely proportional to the radius of the circle. If the radius is halved, then the acceleration is doubled.

Centripetal acceleration is directly proportional to the square of velocity. If the velocity is doubled, then the centripetal acceleration is increased by a factor of 4.

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Air oil separator mark 3:

Posted Image

All parts apart from street elbows are made from 28 and 15 mm copper pipe. Chapeau made from rolled flat 28 mm pipe and a short piece of 15 mm pipe reduced in diameter to 13.2 mm.

Cone made from 28 mm pipe. Tangential inlet pipe made from 15 mm pipe reduced in diameter to 13.2 mm.

Got a mark 4 version coming. Will be easier to make. Mark 3 can't be cobbled together unless one has access to a machine shop.

ID of breather hose, P/N A660 016 0081 is 12.8 mm.

Edited by tolsen

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Looking again at cyclonic vacuum cleaners like Dyson's, I'm thinking greater effect may be achieved with the tangential inlet lower down...?

post-95-1306126242_thumb.jpg

I haven't your grasp of the physics, TK, but that's just the way it looks to me. Maybe precipitation of liquid oil is different than dusty particulates :dunno:

Bil :senile:

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I won't get the flow to go in a circle if I fit the inlet pipe that low. It is hard enough to get it right higher up. The problem is simply due to geometry and diameters.

Another gadget. As stated it stops oil wetting the internals of rocker cover from creeping out into breather hose:

Posted Image

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Ooh, I like that: simple and ingenious.I asked at Smartz "all this time, I haven't bothered to check. Kane says the upper breather on the gasser is 10 mm (3/8") ID, but I honestly don't know -- is the breather on the cdi 13 mm (1/2")?"

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Thanks for clearing that up for me, TK.

And Francesco, I am pretty certain - months since I worked on it - that the OEM tubing I.D. is 13mm. I used 1/2" I.D. tubing most recently, with a 1/2" insert coupling and had to clamp it tightly to fit the OEM tubing side. I notice that TK reports it is 12.5mm but that is less than 1/2" and I am certain ours is bigger than 1/2". maybe someone with EPC can check if the 2005-6 part is the same number as he quoted.

You know, as much as I have fiddled with this tubing, I can't say I have paid a lot of attention to how the rocker cover end is fastened. Your diagram of the clever "Stop the creep" device shows a bell end that I suppose must have a clamp on it to hold it onto a nipple on the rocker cover. is that right? And what sort of clamp is it please?

What I have done is simply cut the existing CCV tube about 5cm from the rocker cover outlet and use a thin-wall, low-pressure, brass insert coupling with two s/s gear clamps. I think my coupling may be long enough to make it do double duty something like this, if I cut the OEM tube shorter:

post-95-1306132333_thumb.gif

Have to check that in the next few of weeks. Lots else on my mind at the moment.

Bil :sun:

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Ah... thanks, man. I don't have a release tool so I guess I'd just destroy it and replace with another universal type of hose clamp.You are a fount of information, sir! :bowdown:

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