ever water ski?
Wear Rates Related to Engine Speed
- Thread starter AEHaas
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The valve train wear just doesn't seem right.
I mean, 15X the wear when at idle vs. high speeds?
Maybe there is an individual engine problem, or the wrong oil was used for the test.
I mean, 15X the wear when at idle vs. high speeds?
Maybe there is an individual engine problem, or the wrong oil was used for the test.
BTW, thank you for posting the test results.
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Yes, but as Sammy Haggar says, "I can't drive 55"...
I'll just keep doing what I'm doing and quite trying to do better (yeah right)... Now, where is my good oil at?!?!
He couldn't "drive" period! He blew out the transmission of the Ferrari used in that video, which he owned...
(sorry, Mod a Van Halen board...)
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First, the title of the post was misleading. The numbers referred to friction, not wear. Wear is not directly proportional to friction on a lubricated surface.
Note that the numbers are all calculated, or computer modeled, not actual measurements. Considering Taylor did the work, they are probably reasonable. still, they aren't measurements and the Taylor's calculations contain several assumptions.
Then the way the data was presented was confusing, even once you recognize that it's total friction (mostly drag from shearing oil), not wear.
If you go to the actual paper and cogitate a bit,
http://www.eng.auburn.edu/~jacksr7/SAE2002013355.pdf
you can see that the valve train actually has a bit more friction loss at high speed, not a lot less.
AEHaas's presentation gave valve train friction as percentage of the total. When you consider that the total friction loss was 392 Watts total at idle and 7462 total Watts at high speed.
I have a feeling "friction" in this example equates to power consumption, not wear. I am not surprised by the high valve train consumption at idle as the engine is overcoming the force of the valve springs. I'd get tired hand cranking a valve train, but I could spin an unloaded crank for quite a while.
Arguing against this theory can be:
1. Energy recouped from the springs on the backside of the cam lobe.
2. Inertia from the reciprocating mass of the valve train increasing as rpm spools up, though way less than the pistons.
Thoughts?
Arguing against this theory can be:
1. Energy recouped from the springs on the backside of the cam lobe.
2. Inertia from the reciprocating mass of the valve train increasing as rpm spools up, though way less than the pistons.
Thoughts?
Tom T, you are correct. You should read the paper with the links in earlier posts in this thread, it's kind of interesting.
Not worth worrying about. Thicker is better for the valvetrain.
An aside here from a renowned author regarding film thickness at the top ring (response to an email of mine):
Ali,
Thanks for the note. I've seen these slides before, but unfortunately I've never seen it presented live to be able to ask questions. I guess that the argument is that this is a starved lubricant condition, and the low vis oils have a higher flow and a better chance at getting to the ring/bore surface, even though they would provide lower film thickness in a fully flooded condition.
Film thickness is probably not the issue at top ring reversal, where we're always in boundary lubrication anyway. But, oil starvation would be an issue. Anything that promotes getting lubricant to the contact will be beneficial for maintaining the antiwear films. Unfortunately, too much lubricant at the top ring causes increased oil consumption. So, there's always a balance between too much and too little oil. This can be influenced by oil ring tension and cylinder bore finish as well as oil viscosity.
Regards,
Eric
Eric W. Schneider
I say that thin oil has benefits especially in the area where normal wear limits the usefulness of a motor. The rings and compression is the end of most engines under normal wear conditions.
aehaas
Ali,
Thanks for the note. I've seen these slides before, but unfortunately I've never seen it presented live to be able to ask questions. I guess that the argument is that this is a starved lubricant condition, and the low vis oils have a higher flow and a better chance at getting to the ring/bore surface, even though they would provide lower film thickness in a fully flooded condition.
Film thickness is probably not the issue at top ring reversal, where we're always in boundary lubrication anyway. But, oil starvation would be an issue. Anything that promotes getting lubricant to the contact will be beneficial for maintaining the antiwear films. Unfortunately, too much lubricant at the top ring causes increased oil consumption. So, there's always a balance between too much and too little oil. This can be influenced by oil ring tension and cylinder bore finish as well as oil viscosity.
Regards,
Eric
Eric W. Schneider
I say that thin oil has benefits especially in the area where normal wear limits the usefulness of a motor. The rings and compression is the end of most engines under normal wear conditions.
aehaas
There's also better cooling and cleaning when some oil gets into the top ring groove.
I'm noticing more metallic engine noise since drianing the 20w-20 and adding 5w30. But it's still a bit less than with 5w-20.
I'm noticing more metallic engine noise since drianing the 20w-20 and adding 5w30. But it's still a bit less than with 5w-20.
" ever water ski? "
Hmmm, reasoning by obscure analogies. Analogies are primarily a tool of argument and not a good tool for reasoning. Analogies are good for argument because if a person's mind already accepts "Z" and you are able to convince them that "X" is just like "Z" then you are likely to win them over to also believing "X". Unfortunately you have done nothing to actually prove X or Z in so doing.
Hmmm, reasoning by obscure analogies. Analogies are primarily a tool of argument and not a good tool for reasoning. Analogies are good for argument because if a person's mind already accepts "Z" and you are able to convince them that "X" is just like "Z" then you are likely to win them over to also believing "X". Unfortunately you have done nothing to actually prove X or Z in so doing.
That is why you weight each part before assembling an engine and then after you are down with validation process you tear down the engine and clean and re-weight the part's on an analytical scale. If UOA has been performed at regular interval's dureing the validation process you can really get some serious insight into where the wear is takeing place!! If you use radio isotopes and electric elements for tracking both specific wear items and temp and flow rate of oil in the various portions of the oil circuit you gain a little bit bigger chunk of the picture.
Well it is really a way to explain in a way for some who don't have any idea . Nothing to prove .
“Not worth worrying about. Thicker is better for the valve train. “
This study goes against that statement:
Oil Development for Nascar Racing, Jayne et al. SAE paper 2000-01-3553.
This is a study from the late 1990’s using one SH and six SJ motor oils. Four mineral and 3 synthetic oils were tested in a 358 CID engine with 12:1 compression on a dynamometer. New engines were broken in with the test oils initially using low loads and RPM for appropriate time periods.
Then the engines were put through 100 pulls, each pull started with the oil temperature at 230 F. Oil and coolant were pre-heated to 160 and 120 F before the engines were even started. They stated the tests overall were more severe than when actually racing.
Engines were torn down and inspected for camshaft/lifter wear, ring welding and wrist pin bore wear.
The worst performer was a European 5W50 synthetic with high detergent package.
Middle of the road performance was from the 20W50 synthetic but the 20W50 mineral based oil was better.
The best overall was the 10W30 synthetic motor oil. They stated that this oil and the second best oil, the 20W50 mineral based oil, both used the same basic additive package - meaning the same type and amount of AW, EP, detergents and others. I suspect that there was no VII in the synthetic oil however.
The 10W30 oil showed minimal camshaft/lifter wear, no ring welding at all and no scuffing. All other oils showed ring welding though the amount varied. Did the second best oil, the mineral based 20W50, thin with use because of VII used. Maybe this helped its overall performance. Maybe this is why some people swear by the use of mineral based instead of synthetic oils in their race cars. Maybe a thinner synthetic would work better than a thicker mineral based oil?
aehaas
This study goes against that statement:
Oil Development for Nascar Racing, Jayne et al. SAE paper 2000-01-3553.
This is a study from the late 1990’s using one SH and six SJ motor oils. Four mineral and 3 synthetic oils were tested in a 358 CID engine with 12:1 compression on a dynamometer. New engines were broken in with the test oils initially using low loads and RPM for appropriate time periods.
Then the engines were put through 100 pulls, each pull started with the oil temperature at 230 F. Oil and coolant were pre-heated to 160 and 120 F before the engines were even started. They stated the tests overall were more severe than when actually racing.
Engines were torn down and inspected for camshaft/lifter wear, ring welding and wrist pin bore wear.
The worst performer was a European 5W50 synthetic with high detergent package.
Middle of the road performance was from the 20W50 synthetic but the 20W50 mineral based oil was better.
The best overall was the 10W30 synthetic motor oil. They stated that this oil and the second best oil, the 20W50 mineral based oil, both used the same basic additive package - meaning the same type and amount of AW, EP, detergents and others. I suspect that there was no VII in the synthetic oil however.
The 10W30 oil showed minimal camshaft/lifter wear, no ring welding at all and no scuffing. All other oils showed ring welding though the amount varied. Did the second best oil, the mineral based 20W50, thin with use because of VII used. Maybe this helped its overall performance. Maybe this is why some people swear by the use of mineral based instead of synthetic oils in their race cars. Maybe a thinner synthetic would work better than a thicker mineral based oil?
aehaas
Thicker is better at idle for the valve train at lower engine speeds.The oil gets displaced faster than at higher engine speeds. The valve train is hard to lubricate especially in the high valvespring rates in cam in block engines ,with out anti wear additives there would be a major wear problem. I would look at the oil comparison you used as not thick or thin oil but as the oil with the least amount of viscosity improvers will at the highest pressure point will have the highest viscosity . As I would guess that the 5w20 oil used in todays motor have minimal vi improvers as compared 5w30 oils etc which is why they are doing so well.I would also guess there is minimal vi improvers in the 10w30 syn oil mentioned. I will standby my statenent that the thicker 15w/40 oil is better for the valvetrain protection at the lower speeds and 15w/40 oils would most likly be hdeos which are very well made oils vith minimal vi improvers and higher than average additives which are most important in valve train protection.
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