Relationship of RPM on power to operate valvetrain

[Warp Speed]

Yes I agree. The lifters on the closing side of the lobe try to propel the camshaft forward, equalizing (mostly), the force required to operate and compress the springs that are in the opening phase. That is what happens at low speed, when we hand crank an engine over with the valvetrain installed.All the spring forces sort of cancel each other out as far as the torque required to turn the camshaft as a whole. My question relates to this, now operate this same engine at 7-8000 RPM. Are the spring forces still equalizing the torque required to turn the camshaft as a whole? I suspect that they are not, and that there is probably somewhat of a linear curve showing increasing torque required to turn the camshaft at these speeds that has nothing to with the increased friction of high RPM, which I agree is increasing,but a different conversation.Thanks for your thoughts, I have no tangible or hard defined answers, just more questions. Probably, should just learn to go to sleep sooner

I gave you a "tangible, hard defined answer", or I thought I did anyway............? Lol

[Tom Walker]

Yes, I see what you mean and I agree, until we turn the engine to 7-8000 RPM, and that is what my question relates to. Do those forces still enable the camshaft to turn with the closing valves off setting the forces of the opening valves at elevated RPM. My curiosity was centered around the idea, that I believe the inertial loads on the valvetrain begin to cause less closing force imparted to the closing ramps of the camshaft and therefore the valvetrain would require more torque from the engine as a function of losing that closing force at high RPM, high RPM the game changer. Thanks Warp Speed for your response.

[digger]

there is a good pdf on web

"calculation of friction in high performance engines" produced by Ricardo

here is an extract

[MadBill]

Great chart! A few surprises there for me:
o Less ring friction than I had been led to believe, and more piston skirt.
o WAY more oil pump than water pump friction.
o Less windage than I expected. (But presumably minimized compared to most production-based race engines.)
o And to the thread title question, slightly less cam/tappet friction power at high RPM!

[Tom Walker]

Great stuff there. Very informative. Thanks.

[statsystems]

Great chart! A few surprises there for me:
o Less ring friction than I had been led to believe, and more piston skirt.
o WAY more oil pump than water pump friction.
o Less windage than I expected. (But presumably minimized compared to most production-based race engines.)
o And to the thread title question, slightly less cam/tappet friction power at high RPM!

I would suspect those would be pretty things rings if the data is relatively recent.

[digger]

Great chart! A few surprises there for me:
o Less ring friction than I had been led to believe, and more piston skirt.
o WAY more oil pump than water pump friction.
o Less windage than I expected. (But presumably minimized compared to most production-based race engines.)
o And to the thread title question, slightly less cam/tappet friction power at high RPM!

The whole document has more info on all of the above. It also looks at a fired engine vs motored and the results are drastically different for some components.

[Warp Speed]

o And to the thread title question, slightly less cam/tappet friction power at high RPM!

?????

[digger]

i would call the cam tappet contacts for the most part constant with rpm

[Warp Speed]

So we are modeling friction of various surfaces.
This is only a partial player in the thread subject "Relationship of RPM on power to operate valvetrain".
Also, a sliding follower has differing frictions through rpm vs a roller, again, if purely looking at friction.
One more note, how many here have tested anything at 9000rpms.........let alone have this rpm as the start of the testing?!?

[MadBill]

o And to the thread title question, slightly less cam/tappet friction power at high RPM!

?????

Do I interpret the above as skepticism? I'm looking at the width of the dark blue band representing "cam/tappet contacts" FMEP*and noting that it is slightly narrower at 16,000 RPM than at 9,000, representing smaller losses. (*Also seen in the narrowing at the upper range of the mauve band in Digger's post two up.)

[Warp Speed]

o And to the thread title question, slightly less cam/tappet friction power at high RPM!

?????

Do I interpret the above as skepticism? I'm looking at the width of the dark blue band representing "cam/tappet contacts" FMEP*and noting that it is slightly narrower at 16,000 RPM than at 9,000, representing smaller losses. (*Also seen in the narrowing at the upper range of the mauve band in Digger's post two up.)

I took the graph as showing the friction is still rising, just becoming a smaller percentage of the overall frictional loses. I definitely could be reading it wrong, but I'm more skeptical of your apparent use of the graph to base an assumption related to the original thread topic.
As I mentioned earlier, sliding tappets/followers vs roller style have differing friction levels throughout the rpm range.
I assume, with the rpm range used, this data and the following models are based on OHC designs in F1 or Moto GP. Definite friction disparity between them and a pushrod, overhead valve system.
I've witnessed pushrod system measurement more times than I could ever count.

[hoffman900]

Jay,

Is this a little closer to what you've seen?

[digger]

Jay,

Is this a little closer to what you've seen?

that also suggest a falling of the torque but more so

[hoffman900]

Jay,

Is this a little closer to what you've seen?

that also suggest a falling of the torque but more so

That was presented by Dr. Andrew Randolph of ECR for a flat tappet NASCAR engine. I think these values would represent the base case scenarios for most engines considering all the R&D. The NASCAR builders are using <150lbs of seat pressure (at least with the flat tappets they were).