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tolsen

More power out of your Cdi - for free!

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I did not say it does not matter, but dispersion through the air is equally bad. Unless there are magic fairies in the cat that remove all the carbon and impurities in this vapour as it is burned -- notwithstanding the increased fuel consumption caused by this oil vapour sludge being forced into the intake -- the net effect is the same... which makes the discussion moot. I maintain that the open catch can is the most environmentally sensible approach, as the waste oil then ends up not on the road, not in the air, but in a container bound for a waste oil recycler.

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Go to any decent pneumatic supply shop and pick a small coalescing filter. A coalescing filter is meant for oil removal, a normal particulate filter gets soaked quickly, is not very efficient and is the wrong type for oil removal. A coalescing filter will drip the oil out into the bowl nicely.

Would a small coalescing filter work effectively at such (near-ambient) low pressures? Ebay has dozens of listings, some of them small and cheap enough for this purpose.

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Would a small coalescing filter work effectively at such (near-ambient) low pressures? Ebay has dozens of listings, some of them small and cheap enough for this purpose.

I think the engine will blow seals if you fit any of those pneumatic air oil separators as too much pressure drop or restriction. Better running with a road draft tube. Have just asked the manager of a local vehicle MOT test station and got confirmation that mine will pass the annual MOT vehicle test with road draft tube fitted. No such thing is on their check sheets so I in the clear!

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Very little pressure drop through a coalescing element. Basically a fibreglass mesh encased in foam. Well worth adding a very light pressure relief if you are worried. Much the same idea as a chunk of foam in a coffee can, but well optimized for the task.An idea: Temporarily tee off before the element, run the tee into the cabin, rig a simple manometer to see what crankcase pressure you are running under load.Anyone have an idea what kind of PCV flow an engine our size can produce under worst-case conditions? I have a lot of pneumatic equipment around including flow-meters, I can rig a test if I know what flow rate to use.

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:popcorn:The "road draft tube" works.

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Just a guess based on watching the tube on certain days, you are below 5 CFM @ 0PSI. You have about 16" Oil to work with before your dipstick tube is your new vent from the bottom of the crankcase. And if Oil is less dense than water, you are looking at a maximum pressure drop of 0.5psi.

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Anyone have an idea what kind of PCV flow an engine our size can produce under worst-case conditions?

Worst case condition is blockage in breather pipe. Crank case pressure will quickly build up to cylinder firing pressure perhaps around 40 bar (I measured around 33 bar when cranking engine and checking cylinder compression without having inhibited engine from firing). Obviously something will have to give, probably a hose, seal or rocker cover so we'll never see that high pressure.

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Worst case condition is blockage in breather pipe. Crank case pressure will quickly build up to cylinder firing pressure perhaps around 40 bar (I measured around 33 bar when cranking engine and checking cylinder compression without having inhibited engine from firing). Obviously something will have to give, probably a hose, seal or rocker cover so we'll never see that high pressure.

In my experience, the "relief outlet" is the dipstick tube :o

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In my experience, the "relief outlet" is the dipstick tube :o

Not so good then Bil. Dipstick tube goes to bottom of sump.

Posted Image

Any pressure buildup in crankcase exceeding 0.5 m head of lube oil and the whole contents of the sump shoots out dipstick tube. Perhaps using a pneumatic coalescent filter is therefore not very Smart unless dipstick tube is shortened?

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Not so good then Bil. Dipstick tube goes to bottom of sump.Any pressure buildup in crankcase exceeding 0.5 m head of lube oil and the whole contents of the sump shoots out dipstick tube. Perhaps using a pneumatic coalescent filter is therefore not very Smart unless dipstick tube is shortened?

Yes, lots of oil shoots out the dipstick and makes a mess of the engine compartment! A coalescing filter is not suitable, in my experience.Bil :senile:

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Is the replacement hose a 'one piece' or did you splice 2 together ?Hose source/part-no's please :rolleyes:

2 with exhaust tube.Pour les pièces utilisé:1. radiateur hose #7694 chez UAP.2. Bout de tuyau d'échapement #548621 chez canadian tire de 18'' de long x 1''3/4 et il est un peu plus gros d'un bout.(C'est parfait car la durite du haut que l'on garde qui va a la valve a un bout un peu plus gros.3. Le gasket que vous faite fabriquer(celui en noir sur la photo du post plus récent) Lorsque vous aurez couper la durite acheté et le tuyau d'échapement de la bonne longueur, les deux durites (haut et bas) vont êtres reliées ensemble par le tuyau d'échapement qui ne sera pas apparent. Relié le tout avec des collets et le tour est joué.

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Here is a sketch showing the design of my cyclone air oil separator. Overall inside diameter of the cyclone is no more than 22 mm. Breather gasses are injected at high speed into the separator through a nozzle. Oil is heavier than air and will be partly separated out. Steam will be returned to engine via air outlet and into TIK pipe. Returning steam to inlet should in theory give a marginally higher engine efficiency.

Posted Image

Oil can be directed to a catch tank or be plumbed back to sump via sounding tube or turbo oil return pipe.

Mark 1 prototype was too large but did work. The cyclone needs to be small in diameter to be effective.

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Interesting. But I'm having trouble visualizing it so small... 22 mm overall ID?

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22mm is a bit small perhaps to make all that happen - here is a picture of the VW system -VW Oil seperatorCheers,Cameron

Thanks for that photo. There is not much space and I don't wish to increase the length of hoses by placing the separator in a different position. A smaller diameter means higher angular velocity and higher g-forces so more efficient separation.Query for you: Which way should the breather gasses spin to benefit from Coriolis acceleration on the northern hemisphere?

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Does the smart's lower breather go mainly positive (forcing vapours and air out of the crank case), or negative (taking in air from the TIK)? I thought it was more the latter than the former.

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Does the smart's lower breather go mainly positive (forcing vapours and air out of the crank case), or negative (taking in air from the TIK)? I thought it was more the latter than the former.

The Cdi only has one breather pipe. The breather gasses come out of rocker cover and are piped to TIK pipe just before turbo.

Reason for making the cyclone small in diameter is this:

Posted Image

Velocity v is given by the flow of breather gasses and size of nozzle. More blowby will increase flow hence increase velocity.

A large radius will reduce centripetal acceleration and a small radius will increase centripetal acceleration.

A small radius and high velocity should therefore in theory give better separation.

Quod erat demonstrandum.

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From the VW separator link:

BMW has an ongoing issue with oil separators freezing in cold weather if driving is done before the vehicle is fully warmed

Not sure how you are going to address this problem, tolsen.And @ SameGuy: That is right; there is no direct ventilation of the lower crankcase in our cdi. How is it ventilated? Blow-by and other gas leakage to the top-end.And: LINK to "Coriolis Effect" article

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From the VW separator link:Not sure how you are going to address this problem, tolsen.And @ SameGuy: That is right; there is no direct ventilation of the lower crankcase in our cdi. How is it ventilated? Blow-by and other gas leakage to the top-end.And: LINK to "Coriolis Effect" article

Making separator small means less surface area so less heat loss and less cooling. Won't increase length of hoses - minimal increase in heat loss and cooling. Assume these measures will suffice in avoiding the separator blocking up due to steam condensing and freezing.Coriolis effect on a cyclone is negligible but some of you may already have noted that mine rotates counter clockwise hence a microscopic increased performance on the northern hemisphere.

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I think you are on the right track with a cyclonic separator, sir.

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Planning to make the various parts up by metal spinning copper tubing and plate. Copper is easily formed, joined and does not corrode. The design is such that it is impossible for any of the parts, if broken loose, to enter TIK pipe and cause unrepairable damage to turbo and engine.

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My primary concern with this small diameter inlet is the reduction of the existing 13mm CCV tubing. If reduced, thereby creating back-pressure to the crankcase venting, one wonders where the critical venting pressure level is. How much reduction is too much?

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My primary concern with this small diameter inlet is the reduction of the existing 13mm CCV tubing. If reduced, thereby creating back-pressure to the crankcase venting, one wonders where the critical venting pressure level is. How much reduction is too much?

Pressure increase caused by the nozzle is not much - certainly not sufficient to shoot any oil out of dip stick tube.I am experimenting with different nozzle sizes and cyclone lengths etc in my quest for the optimum design. Got the prototype set up with transparent hoses and instrumentation so I can assess what is going on. It would have been nice to have a separator made out of glass but too tricky for me to make in my shed.PS. My open ended road draft tube caused higher pressure in crankcase than my current cyclone air oil separator prototype. Edited by tolsen

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