Quote:
Originally Posted by Walt Fricke
John D: On your graph, what are the units on the vertical coordinate? Zero something is part way up?
One trace looks like it is the cam lobe (nice bell curve). What is the other?
On the cam trace, the angle (tangent, differential) at any point is the acceleration?
Am I correct that more lash = less valve open duration? So the 906 would wake up because there was too much duration (overlap?) until hot? Would spend less time at the early and late small openings with lower flows, and more in the fat part?
This may be helping me visualize part of Paul's point: as the lash opens with heat, the valve stays closed longer (thus cooling more). The low angle of this ramp area means a small change in lash leads to a relatively large change in seat time?
I still don't quite understand why you can't do with the grind shape what you can do with altering lash as far as seat time is concerned. What good is the part of the ramp the rocker/follower never sits on?
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The units are right are for the velocity curve. in/degree. Zero would be where the line goes flat. I cropped the graph small, the valve lift curve units would be on the left.
Velocity curve.. Acceleration is another curve not included in this graph.
Yes, increasing lash reduces the time the valve is open. This ramp is way too long almost 30 degrees on the closing side. A GT2 profile would have a 10 to 12 degree long ramp in comparison.
The 906 is an extreme example of a very safe profile. it takes 30 degrees to move the valve .008" vs. 12 degrees on the GT2. If I get a chance I will overlay the GT2 with a 906.