Breather again

Hi

Previously had a XS650 breather.
I now intend to try a new and perhaps better solution
It is a Ducati valve:http://www.ebay.com/itm/DUCATI-848-1098-1198-S-R-CNC-BILLET-ALUMINUM-CRANKCASE-ENGINE-OIL-BREATHER-VALVE-/271159259267?hash=item3f2259f083&vxp=mtr
It has admittedly little big tube out, but I intend to do something about that.
My question is: Am I doing something stupid if I connect the ventilation from this valve into the back of the KN filter and allows the engine to get the evaporation from the crankcase.
It was well so roughly that it was before I thought. (in the old days)
What do you think guys, is it a good idea?












Vidar

I think you are safest sticking it through the oil tank.

Blow-by is a combination of soot and other shit left over from poor or incomplete combustion, oil, gas and water.


In my opinion, I wouldn't necessarily want to put this straight back through the engine again.
That's why people use catch cans, but at least bubbling it back through your oil tank will allow the caustic gas to vent off, the solids to be filtered out (to a limited extent) and the watery condensate to sink to the bottom of the tank (hopefully below the feed pipe)

I always find it funny when I see these breather pipes directed at the rear chain as some kind of chain oiler! This stuff is the last thing on earth I'd want to paint a chain with!

I'm sure others will disagree with me though!

gtiller said:

............ I wouldn't necessarily want to put this straight back through the engine again.
That's why people use catch cans, but at least bubbling it back through your oil tank will allow the caustic gas to vent off, the solids to be filtered out (to a limited extent) and the watery condensate to sink to the bottom of the tank (hopefully below the feed pipe).........

Click to expand...

I thought it was only governments that wanted to route it back to the intake :shock: All jokes aside, I vote for a catch can or the oil tank.

I would not put the vented gases into the air intake unless the law requires it, and would likely go around the law if it did.

Venting to the oil tank affords the possibility of recovering oil mist, but this is not likely to happen unless the tank is fitted with an oil scrubber vent (not a factory set up .... you will have to rig up something on your own). On another thread, there are those who think the blowby gasses in the oil tank are a no-no, but I discount this as the oil comes back from the engine contaminated with blowby gasses regardless.

Venting to a catch bottle will not recover much oil as the oil mist is expelled with the gasses unless the bottle is fitted with an oil scrubber.

Routing the vent to the rear chain is a waste of time, gtiller's concerns not withstanding, as the oil doubtfully even hits the chain due to the forward moving wind under the chain guard. On my Atlas, such routing (factory set-up) only served to coat the drive side crankcase with oil, until I rigged up a scrubber.

My first attempt at an oil scrubber was to fit a catch bottle (a 4 Oz. wide mouth jar) with a lid having two tubes, one long and one short. The short tube was on the engine side so oil could drain back to the sump. The jar was filled with steel wool, and the expelled oil mist/gasses had to travel thru the steel wool before exiting the long tube which led to the oil tank, or place of your choice. This mod stopped the oil deposition on the drive side cc.

Slick

Venting the crankcase is essential for many reasons. I have a Porsche racing engine assembler friend who was telling me that they were having trouble with too much pressure building in the crankcase. I never found out what their solution was. It is important to remember that it is one thing to let the pressure out but one must also insure there is a path for an equal amount of fresh air to come in. I have seen a number of young hotrodders that completely ignore this or are probably unaware of this fact. In the old days we usually just added a bunch of vents to the valve covers and let it be. One of our members in Australia had a fairly good solution for venting and cooling his engine. He had a good intake point for fresh air and a nice output set up. If I were one of you guys with the big amp alternator and fancy regulation system, I would adapt a small electric in line turbo fan and provide an equally large fresh air inlet area. Turbovent. The volumes of air needed to be moved would have to be worked out though. There you go. My 2 cents worth.

If you modified the oil return hole to be lower, just run a big tube out to the back, there will not be any oil mist or very little. If you did not modify the oil return hole, then there will be some oil mist and oil droplets so then run it to the oil tank, from there you can run the pipe to the air filter or the athmosphere.

Jean

aceaceca said:

snip - It is important to remember that it is one thing to let the pressure out but one must also insure there is a path for an equal amount of fresh air to come in. I have seen a number of young hotrodders that completely ignore this or are probably unaware of this fact. In the old days we usually just added a bunch of vents to the valve covers and let it be. One of our members in Australia had a fairly good solution for venting and cooling his engine. He had a good intake point for fresh air and a nice output set up. If I were one of you guys with the big amp alternator and fancy regulation system, I would adapt a small electric in line turbo fan and provide an equally large fresh air inlet area. Turbovent. The volumes of air needed to be moved would have to be worked out though. There you go. My 2 cents worth.

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I don't quite follow this - the whole point of a read valve is let air out but not in again. The result should be that you end up with a slight under pressure in the crankcases.

/Steve in Copenhagen.

Not true - you actually end up with a slight vacuum in the crankcase, not pressure.

When the piston comes down, the air and other miscellaneous crap is expelled through the reed valve.

When the piston goes up, a small vacuum is created in the crankcase.

Because there is no pressurisation (other than in the cylinder of course) it is how the method can be used to reduce the number of minor leaks and oil weeping of the crankcase.


This may not be desirable behaviour in larger engines whereby the vacuum, if it is large enough will cause loss in performance. But for small displacement engines (like ours) we are all good.

Also, with more cylinders, or where there is an offset crankcase scenario, the crankcase pressure is more balanced (one piston is raised while the other is lowered, which equalises the crankcase pressure) compared to our engines where both pistons are raised at the same time (leaving a vacuum underneath)

I've got Jim Comstocks reed valve sump breather. It is amazing just how little pumping of gasses there actually are with these devices. There is very little gas / oil, anything coming out of the vent into the oil tank.

Remember that without a reed valve you will have 850cc of gas pumping out AND back again every revolution... that's 1700cc of gas pumping per revolution... that's 113,333cc of gas per second at 4,00rpm (assuming my maths is correct here)... in this case, its easy to visualise oil, froth, snot and shit flying everywhere.

With a reed valve, only the tiniest amount of blow by gasses are pumped out each rev.

So, my two-penneth, assuming your reed valve installation works as effectively, would be that the simplest, neatest, and perfectly functional idea is to vent to the oil tank.

All IMHO only of course.

gtiller said:

Not true - you actually end up with a slight vacuum in the crankcase, not pressure.

When the piston comes down, the air and other miscellaneous crap is expelled through the reed valve.

When the piston goes up, a small vacuum is created in the crankcase.

Because there is no pressurisation (other than in the cylinder of course) it is how the method can be used to reduce the number of minor leaks and oil weeping of the crankcase.


This may not be desirable behaviour in larger engines whereby the vacuum, if it is large enough will cause loss in performance. But for small displacement engines (like ours) we are all good.

Also, with more cylinders, or where there is an offset crankcase scenario, the crankcase pressure is more balanced (one piston is raised while the other is lowered, which equalises the crankcase pressure) compared to our engines where both pistons are raised at the same time (leaving a vacuum underneath)

Click to expand...

When Steve said 'Under pressure' I think he mean under - as apposed to over - pressure, AKA a vacuum!

Steve has spent a long time in Denmark... and is, I suspect, forgetting how to speak English...!

(BTW Steve, my own 3 years in CPH is coming to an end in Dec)!

I love Copenhagen, but there is a limit as to how much surstromming us Brits can handle!!!

The Cosworth V8 DFV-series racing engines have sump-pumps (i.e. forced breathers) on them that 'all but suck the crank out', in the words of my late race-engine guru/mate. I was going to do something similar to my racing Harley motor, but a big crash (which nearly split me in two) put a halt to that development!

vidar hjelm johansen said:

Hi

Vidar

Click to expand...

I think that will work fine as long as you have openings/holes in the TS side of the crankcase to accommodate it. If you have sealed up your holes in the TS side of the cases, as many people a seem to be doing these days, then it will not be effective. Anyone with the TS breather needs to have ventilation to vent.

Hi
Yes, I hope it works out well, the holes you mention are open.
I understand that most people believe that it is better to lead oil vapor back into the tank instead of in the air filter.

Does it than means, that it is better to contaminate the oil in the oil tank with whatever might come with the vapor, than burning it up over time. :?:

Vidar

vidar hjelm johansen said:

I understand that most people believe that it is better to lead oil vapor back into the tank instead of in the air filter.

Does it than means, that it is better to contaminate the oil in the oil tank with whatever might come with the vapor, than burning it up over time. :?:

Vidar

Click to expand...

The oil in the oil tank is contaminated before it returns to the tank. Another exposure to the blow by gasses is irrelevant. You cannot burn it up over time, as the engine is constantly producing the contaminants. That is the main reason we have to change our oil ..... the oil never wears out, but becomes too contaminated. IMO, avoiding venting thru the oil tank is over-worrying the issue.

Slick

gtiller said:

This may not be desirable behaviour in larger engines whereby the vacuum, if it is large enough will cause loss in performance.

Click to expand...

Have you measured the loss?

gtiller said:

I love Copenhagen, but there is a limit as to how much surstromming us Brits can handle!!!

Click to expand...

Hmm - better not say this to a Dane (or for that matter a Swede). The one will be insulted that you think that Danes actually have anything to do with inflicting surströmming on an unsuspecting and innocent world, while the other will be insulted that you do not think it the greatest form of food ever known

Fast Eddie said:

When Steve said 'Under pressure' I think he mean under - as apposed to over - pressure, AKA a vacuum!

Steve has spent a long time in Denmark... and is, I suspect, forgetting how to speak English...!

(BTW Steve, my own 3 years in CPH is coming to an end in Dec)!

Click to expand...

Yes, sorry about that, meant negative pressure of course (as opposed to a vacuum).

BTW I've just sent you a pm...

The oil picks up contaminants in the course of doing its job, but I don't know if you can say that more exposure is irrelevant. Yes the engine is constantly producing contaminants, so that means that routing them to the oil tank will result in a faster accumulation of them over time. IMHO I would rather feed them through the engine for immediate removal.
That is not what I did, however. To avoid hacking into one of the few remaining original parts of my 1970 bike (the filter plate), and having to source just the right moulded hose to do the job neatly, I just used a pod filter on the catch tank to vent it to atmosphere. Don't tell the guv'mnt.

Last June I added a Buell XB 1200 R to the fleet. Having acquired a workshop manual I notice that the reed valve is fitted into the timing side crankcase wall, venting into the timing chest. From here it vents up the pushrod tunnels to the rocker boxes, then out to the airbox via umbrella valves. I was thinking this would be a neat arrangement for a Norton, venting out of the existing 850 type timing chest breather.