Crankcase evac ??
#11
07-14-2011, 01:33 AM
Join Date: Jul 2010
Location: Missouri
Posts: 1,414
No, I understood. We're talking about reducing and/or trying to create negative crankcase pressure in either case. Just a different way to skin the same cat. No noticeable power influence was evident in the KLR650 dyno test. Another guy actually came with an elaborate way to measure crankcase pressures and any fluctuation, and it showed no great pressure imbalances. I don't know. I still don't know how or why...at least for sure...why I and some others had an oil consumption drop. The whole deal sounds like a funky snake oil scam. The KLX is not an oil burner whatsoever, so for me it's a moot point now.
I still think i'm going to give it a shot. Might not do crap but i think i found a length of hose kicking around that will work. Worst case, i wasted 20 mins of my time that i would probably have just spent on the forums anyway.
#12
07-14-2011, 04:42 PM
Join Date: Oct 2009
Location: Sonoran Desert, Arizona
Posts: 262
In normal configuration it is impossible for the crankcase to completely vent on one stroke at running speed. The only way that could happen is if the vent were as large as the cylinder bore.
Since the piston is going up and down faster than the crankcase can completely vent, an equilibrium is met. On the down stroke it takes a certain amount of energy to pressurize the crank case. On the up stroke, this energy is given back. The net gain/loss is zero. Any blow-by that is introduced on the down stroke upsets the equilibrium slightly and exits via the crankcase vent.
Applying a vacuum to the crankcase (on a one cylinder engine) will reduce the energy lost on the down stroke. However, since there is now no pressure in the crankcase to help boost the piston back up on the up stroke, there is still a net gain/loss of zero.
The same thing would happen if you were to pressurize the crank case instead of applying vacuum. It would take more energy to move the piston down, but that energy would be given back on the up stroke. Again, no net gain or loss.
Enjoy the experiment, though. It should be fun.
Ron
Since the piston is going up and down faster than the crankcase can completely vent, an equilibrium is met. On the down stroke it takes a certain amount of energy to pressurize the crank case. On the up stroke, this energy is given back. The net gain/loss is zero. Any blow-by that is introduced on the down stroke upsets the equilibrium slightly and exits via the crankcase vent.
Applying a vacuum to the crankcase (on a one cylinder engine) will reduce the energy lost on the down stroke. However, since there is now no pressure in the crankcase to help boost the piston back up on the up stroke, there is still a net gain/loss of zero.
The same thing would happen if you were to pressurize the crank case instead of applying vacuum. It would take more energy to move the piston down, but that energy would be given back on the up stroke. Again, no net gain or loss.
Enjoy the experiment, though. It should be fun.
Ron
#13
07-14-2011, 05:18 PM
Join Date: Jul 2010
Location: Missouri
Posts: 1,414
In normal configuration it is impossible for the crankcase to completely vent on one stroke at running speed. The only way that could happen is if the vent were as large as the cylinder bore.
Since the piston is going up and down faster than the crankcase can completely vent, an equilibrium is met. On the down stroke it takes a certain amount of energy to pressurize the crank case. On the up stroke, this energy is given back. The net gain/loss is zero. Any blow-by that is introduced on the down stroke upsets the equilibrium slightly and exits via the crankcase vent.
Applying a vacuum to the crankcase (on a one cylinder engine) will reduce the energy lost on the down stroke. However, since there is now no pressure in the crankcase to help boost the piston back up on the up stroke, there is still a net gain/loss of zero.
The same thing would happen if you were to pressurize the crank case instead of applying vacuum. It would take more energy to move the piston down, but that energy would be given back on the up stroke. Again, no net gain or loss.
Enjoy the experiment, though. It should be fun.
Ron
Since the piston is going up and down faster than the crankcase can completely vent, an equilibrium is met. On the down stroke it takes a certain amount of energy to pressurize the crank case. On the up stroke, this energy is given back. The net gain/loss is zero. Any blow-by that is introduced on the down stroke upsets the equilibrium slightly and exits via the crankcase vent.
Applying a vacuum to the crankcase (on a one cylinder engine) will reduce the energy lost on the down stroke. However, since there is now no pressure in the crankcase to help boost the piston back up on the up stroke, there is still a net gain/loss of zero.
The same thing would happen if you were to pressurize the crank case instead of applying vacuum. It would take more energy to move the piston down, but that energy would be given back on the up stroke. Again, no net gain or loss.
Enjoy the experiment, though. It should be fun.
Ron
I'll report back on my findings hopefully this afternoon if i can get some other things out of the way.
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