grumpyvette Posted October 23, 2007 Share Posted October 23, 2007 valve float wet flow videos notice how the combustion chamber shape effects flow Quote Link to comment Share on other sites More sharing options...
jt1 Posted October 23, 2007 Share Posted October 23, 2007 Fascinating stuff. I can't understand where the force that deflects the valve stem to the side comes from. Could it be a wave reflection from elastic buckling? jt Quote Link to comment Share on other sites More sharing options...
Cruez Posted October 24, 2007 Share Posted October 24, 2007 Very interesting... ! Quote Link to comment Share on other sites More sharing options...
jt1 Posted October 24, 2007 Share Posted October 24, 2007 posted by some dumbass Could it be a wave reflection from elastic buckling? After thinking that over some more, no way it could be buckling. So what causes the sideways deflection? jt Quote Link to comment Share on other sites More sharing options...
SteelToad Posted October 24, 2007 Share Posted October 24, 2007 One thing that could be a factor ... A coiled spring is always going to have an angle of deflection when it expands because there is always one point with just a little more expansion. Take this spring |/////| The upper edge having more "coil" would have just a little more spring than the bottom edge (overblown example of course). Even if you try to wind it so that the coils begin and end at the same point around the diameter theres always going to be some point with just a little more "spring". When it expands it will push away from the point with the most spring. Quote Link to comment Share on other sites More sharing options...
Cruez Posted October 25, 2007 Share Posted October 25, 2007 Resonance maybe? Quote Link to comment Share on other sites More sharing options...
m4xwellmurd3r Posted October 25, 2007 Share Posted October 25, 2007 One thing that could be a factor ... A coiled spring is always going to have an angle of deflection when it expands because there is always one point with just a little more expansion. Take this spring |/////| The upper edge having more "coil" would have just a little more spring than the bottom edge (overblown example of course). Even if you try to wind it so that the coils begin and end at the same point around the diameter theres always going to be some point with just a little more "spring". When it expands it will push away from the point with the most spring. so basically it causes the spring to put just a fraction more force on one side of the valve, so when the valve floats, it starts to wobble? Quote Link to comment Share on other sites More sharing options...
SteelToad Posted October 25, 2007 Share Posted October 25, 2007 so basically it causes the spring to put just a fraction more force on one side of the valve, so when the valve floats, it starts to wobble? If you're looking for a definitive answer, I'm not your guy. I'm just looking at what makes sense to me. The deflection of the spring to one side would be very minor, but if you look at how quickly and how often they compress and expand, the cumulative effect would have to lead to some wear Quote Link to comment Share on other sites More sharing options...
bjhines Posted October 25, 2007 Share Posted October 25, 2007 There is one aspect of this test that bothers me. It appears they are using a mockup head and turning the cam with an electric motor at controled speeds. The problem I have with any data gathered on resonance in the valvetrain is that THE ENGINE has it's own modes of resonance. There is a good chance that conditions are very different in an actual operating engine. Quote Link to comment Share on other sites More sharing options...
Zmanco Posted October 25, 2007 Share Posted October 25, 2007 There is one aspect of this test that bothers me. It appears they are using a mockup head and turning the cam with an electric motor at controlled speeds. The problem I have with any data gathered on resonance in the valvetrain is that THE ENGINE has it's own modes of resonance. There is a good chance that conditions are very different in an actual operating engine. I was thinking the same thing. If it was a real engine running under its own power, wouldn't there be oil flying all over the place? I saw it more as an example of what it might look like. I'm sure there would be differences between specific types of engines/valve trains as well. Still, it was pretty clever how they kept the speed of the strobe JUST slower than the speed of the valve train so that we could see the full range of motion. If it had been exactly the same, the valve train would have appeared stationary. Quote Link to comment Share on other sites More sharing options...
jt1 Posted October 25, 2007 Share Posted October 25, 2007 Here's another one, about ten yrs old, of a circle track engine, 0.700 lift solid roller, at 7K rpm. About 60 megs. http://www.racingsprings.com/movies/test004.avi I can't believe it doesn't fly all to hell. John Quote Link to comment Share on other sites More sharing options...
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