Product release - new style one way case breather

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jseng1

jseng1

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I’ve been interested in one way breathers ever since the 1980s when Leo Goff used them on his world championship dragster. I tried them but was never happy with the fit until now. This new one way breather fits inside the timing cover so you don’t have to drill holes in the exterior of your cases (potential leaks near the rear tire). For 850s you retain the original breather to the oil tank. For 750s you plug the original cam vent and transfer the elbow fitting to the mag blank plate and plumb it to the oil tank. All necessary hardware is provided. No machine work is necessary but you have to drill and tap threads.

For more info go here:
http://www.jsmotorsport.com/technical_breather.asp

The naked breather with German steel reed valve and 7075 aircraft aluminum housing:
Product release - new style one way case breather


As its mounted in the timing case.
Product release - new style one way case breather


With all the case plugs installed:
Product release - new style one way case breather


Positive pressure is pumped out when the pistons descend. Then the valve shuts and prevents the air from re-entering on the upstroke creating a temporary vacuum. Now there is very little air to be pumped out on the next down stroke. Without the air pressure pumping in and out - leaks are reduced or eliminated throughout the motor.

Demo video here:
[video]https://youtu.be/1YAjg7X763Y[/video]
 
Jim

Have you ever measured the negative pressure that results in the crankcase with this type of reed valve? How does the crankcase pressure compare with a timed breather?

Slick
 
texasSlick said:
Jim

Have you ever measured the negative pressure that results in the crankcase with this type of reed valve? How does the crankcase pressure compare with a timed breather?

Slick
Click to expand...

Its hard to measure the vacuum because the pressure is so low and fluctuates so rapidly. With the one way valve in place the positive pressure at the hose is nearly zero while the pressure inside the case can be slightly negative on the upstrokes. When the blowby hose is dipped into oil without the valve, it actually sucks up liquid when you back off the throttle, then blows it out when you re-open the throttle. This happened to me in an earlier experiment without the valve when I dipped the blowby hose into water and saw it suck the water into the motor - then I had to drain out the oil/water mix. Liquid is never sucked into the blowby hose with the one way valve. The vacuum stays in the motor.

The original rotary valve doesn't work well because of delayed reaction at different RPMs. If it worked they would have kept it on the 850 - but they eliminated it.

Here's an experiment you can do yourself - let your bike idle and loosen the oil cap. Without the one way valve the cap will bounce up and down from the pressure pulses. With the one way valve the oil cap will vibrate but it will stay put.
 
jseng1 said:
Its hard to measure the vacuum because the pressure is so low and fluctuates so rapidly. With the one way valve in place the positive pressure at the hose is nearly zero while the pressure inside the case can be slightly negative on the upstrokes. When the blowby hose is dipped into oil without the valve, it actually sucks up liquid when you back off the throttle, then blows it out when you re-open the throttle. This happened to me in an earlier experiment without the valve when I dipped the blowby hose into water and saw it suck the water into the motor - then I had to drain out the oil/water mix. Liquid is never sucked into the blowby hose with the one way valve. The vacuum stays in the motor.

The original rotary valve doesn't work well because of delayed reaction at different RPMs. If it worked they would have kept it on the 850 - but they eliminated it.
Click to expand...

Highlighted text is my sentiments exactly. I am curious , however to quantify any improvement. I have made some pressure measurements of the timed breather on my Atlas by replacing one of the rocker spindle cover screws with a pressure tap. The pressure I got was negative 16 - 18 inches of water as measured with a Magnehelic differential pressure gauge. The pressure was reasonably constant from 2K - 6K rpm.

Slick
 
I'm considering such a solution for my MK3. I understand that it may create a negative pressure in the crankcase, but I do not understand that it can retain it. This because the pressure difference all the time have the opportunity to equalized. I think that it will happen through the main ball bearing and the new oil return hole.
If you include timing house and create vacum also here then will not air could return to the crankcase.
Am I absolutely wrong or am I on to something?

Vidar
 
Best not to over think these things. I have a Comstock type reed valve on my 920 & it works. The engine is 100% oil tight. Although it is a different engine my Buell XB has a reed valve in the timing cover & that works well also. i.e. No oil leaks.
 
Matchless is right - best not to overthink it. But since we're thinking:

Texas slick - I've removed the rotary valve cam breather on my bike and couldn't test it for vacuum if I wanted to.

Vidar - since positive pressure is eliminated with each downward stroke - every upstroke creates vacuum. The net result means zero pressure is left to be pumping oil through the gaskets.

Some say that more HP is produced (if you can believe the hype). The theory is that instead of pushing and pulling air through the breather each stroke without the valve - the upstroke vacuum created by the valve acts as a spring - pulling the pistons back down thus recovering some energy.

Plugging existing vents in the timing chest helps increase the vacuum and improves the efficiency of the one way breather. The new oil return hole is only there to lower the oil level in the timing chest which is higher than it needs to be.
 
chris plant said:
jim,how much is it
Click to expand...

Chris - Price is at my website - see address below. There are some extra parts that go with the 750 kit that aren't shown yet in the products page. And there is an option for magneto models.
 
jseng1 said:
Some say that more HP is produced (if you can believe the hype). The theory is that instead of pushing and pulling air through the breather each stroke without the valve - the upstroke vacuum created by the valve acts as a spring - pulling the pistons back down thus recovering some energy.
Click to expand...

That sounds like some salesman/engineer talking to me. How could something like that even be measured?

I really like your breather, a K.I.S.S. solution to a long known issue.
 
texasSlick said:
Have you ever measured the negative pressure that results in the crankcase with this type of reed valve? How does the crankcase pressure compare with a timed breather?

Slick
Click to expand...

As usual Comnoz to the rescue, answering the challenging questions requiring specialized instrumentation, specialized test set-up or both.

http://www.accessnorton.com/head-ga...0-30.html?hilit=comnoz breather scope#p324433

comnoz said:
MS850 said:
Ok, please explain why the hose from the timing cover vented to the atmosphere would work better the the hose with check valve.
Click to expand...

Here are some pictures I took several years ago when I was working on an effective breather.
These are scope traces from an absolute pressure sensor installed in the hole where the tach drive had been removed. The engine was running at 3600 rpm on the dyno with a light load.
The sensor converts the pressure to a voltage at real time.
+5 volts is equivalent to 1 bar of pressure
-5 volts is minus 1 bar of pressure
The horizontal center line of the scope is 0 pressure and full screen is +5 to - 5 volts.

Shot one shows a stock open breather from the timing chest on an 850. Note that the average pressure -halfway between peak to peak is above zero and there is a large variation in pressure as the pistons go up and down

Product release - new style one way case breather


Shot two shows what happens with a brake booster valve in the line from the timing chest. Since the check valve lets air out but not back in -there is less air to compress so the pressure swings are smaller and the average pressure is now below the zero pressure line.

Product release - new style one way case breather


Now if you really want to get tricky. Here is a shot of the pressure with a reed valve directly connected to the crankcase and all the holes except one drainback hole plugged between the crankcase and the timing chest.

Product release - new style one way case breather
Click to expand...
 
A nice tidy option, though there will be/should be differential pressure between the timing chest and crank cases. This might have an effect on the returning oil from the cylinder head and timing side main bearing lubrication due to reverse air flow.

Just a thought.

Dave.
 
Interpolating the oscillographs of comnoz, I come up with the following analysis to determine average negative pressure in the cases with a reed valve.

per comnoz, full scale from centerline is one bar. Thus each major division is 1/5 bar (I am assuming there is one more vertical division not seen in the pics).

Interpolating, the positive peak with reed valve is approx. 0.4 divisions, and the negative approx. 0.8, giving a peak to peak value of 1.2 divisions.

The rms value is 0.707 of peak to peak and is equal to 0.84 divisions.

Subtracting 0.84 from 0.4 positive peak equals minus 0.44 divisions. This is the rms avg. of the waveform.

converting negative 0.44 divisions to bar yields negative 0.088 bar, or 35 inches of water.

Thus, the reed valve produces about twice as much negative pressure in the cases as does the timed rotary valve (see my post above).

This level of negative pressure, while good to keep oil from seeping thru gaskets, is insignificant to improve horsepower.

Slick
 
Mark and Texas
I agree that the HP claim is probably sales pitch. I'm not making that claim. Someone else might and I call it "hype". But I have no evidence either way.

Dave
The timing chest is more or less sealed off from the sump. Differential pressure is only a fraction of what you see in the original factory setup.
 
jseng1 said:
Mark and Texas
I agree that the HP claim is probably sales pitch. I don't claim a HP increase. As I said - "Some" others make the claim and I called it "hype". But I have no evidence either way.
Click to expand...

Jim: I read your post and fully understood you were not making a HP claim for your product. My comment was meant to re-inforce yours. Sorry if I was not sufficiently explicit.

Slick
 
Dave
The timing chest is more or less sealed off from the sump. Differential pressure is only a fraction of what you see in the original factory setup.
Click to expand...

I don't believe there will be much if any differential pressure across the crankcase and timing chest with the original 750 timed or 850 breather as they are effectively one chamber. By more or less sealing off the c/case from the t/chest you are creating two chambers and I would expect to see a differential in pressure. The timing chest will be atmospheric while the crankcase pressure will be relative to the action of the pistons and reed valve.

In the photo I missed the new lower drain between the crank cases and timing chest. Do you not think the drain hole by connecting the two chambers will by-pass the valve and therefore negate its effect ?

Dave
 
BMW did a LOT of research into crank case breathing decades ago and came up with a reed valve about the diameter of a 50 p piece and 1/4 inch or so thick. if I could find one I would measure it but I have clearly put it somewhere safe.
We were employing them in the 80s on our so called classic race Norton. The breather fitted to the motor fed back to the oil tank. At engine start up the reed valve could be heard clicking away for a few engine revs and then went silent as it had removed all crankcase pressure and from then on gave only the occasional click as it removed any blow bye on the piston rings. Cost was minimal and just needed at least one brain cell to incorpotate correctly.
At engine start up I once looked intothe oil tank and even with the oil level a couple of inches below the pipe entry point the pressue pulses were deforming the surface of the oil. i was impressed at the amount of pressure generated in Norton crankcases!!!
 
J. M. Leadbeater said:
BMW did a LOT of research into crank case breathing decades ago and came up with a reed valve about the diameter of a 50 p piece and 1/4 inch or so thick. if I could find one I would measure it but I have clearly put it somewhere safe.
Click to expand...

No need to bother as you have already mentioned the BMW reed valve seven times, so let's make this the last.
 
The idea of a gain in HP may be hype but when I was a younger and working as a foreign auto mechanic I remember my boss showing my how tight the PCV system was on a BMW. Pulling out the dipstick would vent the crankcase and lower the idle by a couple hundred RPM.

Dave - There is a return oil drain hole in the timing chest with the original layout. Plugging the original and drilling a new one further down lowers the level so less oil is churned and heated. There is no problem with differential pressure that I can see - I suggest you make your own test to be satisfied.
 
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