Confessions of a Recovering Thickie

[ZeeOSix]

That's why I want it here. Had to go searching. The one from post 326.

This one .. what about it? I already explained it back in post 326. Why don't you go read SubsTech/King Bearing's website and learn about this stuff on your own since you don't seem to believe it when posted here.

All this graph is saying is that the 'sweet spot" for bearing clearance is 0.001 - 0.003". And as I said before, this is the reason that about every ICE made 50 years ago until today have these bearing clearances. Engineers have protected bearing clearances, and that's why they are in this range. Bet your Rouge is the same way. And the fact is, bearings in this range can run a whole range of oil viscosity, and it's also a fact that thicker oil in all of those clearances results in more MOFT. If you'd go study the SubsTech info you'd see that.

 

[chris719]

Because it didn't affect L87's prior to 2021. Because warranty replacements are spec'd back to 0w-20, and the warranty is extended to 150k/10yr.

Yes, all true... but then why do they ship LT1s with 0W-40 with identical bearing clearances? Would this defect even have been noticed if they had been running 0W-40?

This invalidates your prior claims that there is some magic in the design of modern engines requiring or benefiting from 0W-20. From their behavior it is clear that the 0W-20 is inferior other than cost savings for GM via fuel economy.

 

[ZeeOSix]

Because it didn't affect L87's prior to 2021. Because warranty replacements are spec'd back to 0w-20, and the warranty is extended to 150k/10yr.

And maybe they so happened to change the bearing size on the new engines to be able to take 0W-20 better. From what I got from the GM recall info, all those trucks swapped to 0W-40 are suppose to run that viscosity for the rest of their life.

 

[siriusc1024]

This one .. what about it? I already explained it back in post 326. Why don't you go read SubsTech/King Bearing's website and learn about this stuff on your own since you don't seem to believe it when posted here.

All this graph is saying is that the 'sweet spot" for bearing clearance is 0.001 - 0.003". And as I said before, this is the reason that about every ICE made 50 years ago until today have these bearing clearances. Engineers have protected bearing clearances, and that's why they are in this range. Bet your Rouge is the same way. And the fact is, bearings in this range can run a whole range of oil viscosity, and it's also a fact that thicker oil in all of those clearances results in more MOFT. If you'd go study the SubsTech info you'd see that.

View attachment 281049

This graph consists of various data points for bearing clearance and MOFT while holding viscosity constant. Agree?

 

[chris719]

And maybe they so happened to change the bearing size on the new engines to be able to take 0W-20 better. From what I got from the GM recall info, all those trucks swapped to 0W-40 are suppose to run that viscosity for the rest of their life.

I Do Cars tore a recalled engine down and it appears to be bad crankshaft finishing that starts it all.

 

[chris719]

This graph consists of various data points for bearing clearance and MOFT while holding viscosity constant. Agree?

What about this one? Or the higher RPM one?

 

[siriusc1024]

What about this one? Or the higher RPM one?View attachment 281051View attachment 281052

Either works, but I'd prefer to focus on the mid range rpm Zee posted.

 

[chris719]

Either works, but I'd prefer to focus on the mid range rpm Zee posted.

 

[siriusc1024]

View attachment 281053

Where viscosity is the constant, and the variance is rpm. I'll do yours next if you want. I'm stepping through to figure out where our perspectives diverge. Please be patient I'm not trying to be pedantic.

 

[ZeeOSix]

This graph consists of various data points for bearing clearance and MOFT while holding viscosity constant. Agree?

Yes, so what's the point? It's pretty easy to see what it's saying about the optimum bearing clearance in this case. Go to SubsTech and you will see how viscosity influences MOFT .. I think I even posted some in this thread, or a link to the SubsTech page. Might just want to read this whole thread from the beginning, lol.

I said before that bearings with tight clearances (0.001 - 0.002 range) like lower viscosity way more than bearings with larger clearances with thin oil. It's a bad situation to run too thin oil in looser bearings ... the MOFT and pressure distribution gets really bad.

But thicker oil in tight bearings still results in more MOFT and more even wedge pressure distribution. Again, thicker oil has more benifits than not. The Coyote as I showed has rod and crank bearings in the 0.001 - 0.002 inch range, and Ford specs 5W-50 all day long in the Track Pack and Boss 302, for all conditions, even street driving. If thicker oil like that was so "bad", then why are Ford engineers specing it?

 

[siriusc1024]

Yes, so what's the point? It's pretty easy to see what it's saying about the optimum bearing clearance in this case. Go to SubsTech and you will see how viscosity influences MOFT .. I think I even posted some in this thread, or a link to the SubsTech page. Might just want to read this whole thread from the beginning, lol.

I said before that bearings with tight clearances (0.001 - 0.002 range) like lower viscosity way more than bearings with larger clearances with thin oil. It's a bad situation to run too thin oil in looser bearings ... the MOFT and pressure distribution gets really bad. But thicker oil in tight bearings still results in more MOFT and more even wedge pressure distribution. Again, thicker oil has more benifits than not. The Coyote as I showed has rod and crank bearings in the 0.001 - 0.002 inch range, and Ford specs 5W-50 all day long in the Track Pack and Boss 302, for all conditons, even street driving. If thcker oil like that was so "bad", then why are Ford engieers speciing it?

Please. I'll explain. One thing at a time. Not a bunch of different things conflated. Agreed on that one point?

 

[ZeeOSix]

Where viscosity is the constant, and the variance is rpm. I'll do yours next if you want. I'm stepping through to figure out where our perspectives diverge. Please be patient I'm not trying to be pedantic.

Why are we rehashing these graphs when I already explained them in the posts they were originally posted? Just go back and read those, then come back with questions.

 

[ZeeOSix]

Please. I'll explain. One thing at a time. Not a bunch of different things conflated. Agreed on that one point?

Go find all the graphs you have questions about, post them with your specific questions ... one graph at a time in one post at a time. Or just go read the original posts because I explained every one of them pretty well. Not going to play this game.

 

[ZeeOSix]

What about this one? Or the higher RPM one?

Think it was mentioned before, that lower engine RPM, especially with lugging under load, will decrease the MOFT. That graph clearly shows that MOFT goes down with lower RPM, and falls off differently depending on bearing clearance and oil viscosity. There are many factors going on at the same time in journal bearings. Also showed a graph of the MOFT over a 4-stroke engine cycle, and obviously the MOFT was at the minimum on the power stroke - no surprise there. That's why journal bearings wear more on the top side when the massive piston force is pushing the rod down on the power stroke and trying to make the MOFT go to zero. To keep bearings happy, the MOFT always has to be above zero in every way possible under all operating conditions.

 

[ZeeOSix]

Go read all the journal bearing info on the SubsTech website. It's a treasure trove of info from an expert in the industry.

https://www.substech.com/dokuwiki/doku.php?id=engine_bearings

 

[siriusc1024]

Clearly in that graph MOFT decreases with clearance.

In the graph Chris posted the thinner oils don't have as pronounced effect.

Well. I tried. I wanted to explain, but you're not receptive to it I see.

Carry on.

 

[ZeeOSix]

Well. I tried. Clearly in that graph MOFT decreases with clearance. Carry on.

Which graph? Post the graph and make your claim/argument or ask questions. Of course MOFT decreases with clearance depending on what the viscosity and RPM is. You're a long way from fully understanding journal bearings. Go read the SubsTech website and do some self learning.

 

[ZeeOSix]

In the graph Chris posted the thinner oils don't have as pronounced effect.

Well. I tried. I wanted to explain, but you're not receptive to it I see.

I see you edited your post. Post the graph and ask the question. And please go read the SubsTech website, I gave the link ... Jeeeez.

 

[siriusc1024]

Which graph? Post the graph and make your claim/argument or ask questions. Of course MOFT decreases with clearance depending on what the viscosity and RPM is. You're a long way from fully understanding journal bearings. Go read the SubsTech website and do some self learning.

MOFT decreases with clearance.

Effect of MOFT with decreasing clearance isn't as pronounced with lower viscosity. Trends may reverse.

Bearing clearances can be optimized to maintain suitable MOFT.

Bearing clearances can be optimized for a viscosity.

 

[ZeeOSix]

MOFT decreases with clearance.

Effect of MOFT with decreasing clearance isn't as pronounced with lower viscosity. Trends may reverse.

Bearing clearances can be optimized for a viscosity to maintain suitable MOFT.

Look at the other RPM cases too. Regardless, the bottom graph clearly shows that the MOFT decreases due to these factors: 1) Less oil viscosity, 2) Less RPM and 3) More bearing clearance. That still happens at every engine RPM, just at different levels. These trends never "reverse" like you think they "might" ... you're just looking for the "need to use low viscosity" excuse, lol. This is how all journal bearing operate since the day they were invented over 100 years ago.

As mentioned and showed many times in this thread, the optimum bearing clearance is the 0.001 - 0.003 inch range ... that's what the top graph shows. And this is why about every bearing in an ICE is in that range. It's optimum, regardless of what oil viscosity is used. But people believe and grasp onto the misconception that tight bearing clearances can ONLY use low viscosity oil. That's totally false based on all kind of info in this thread, even the Nissan OM outside the US proves that. It's more like tight bearings are the only ones that can successfully use thinner oil for all the reasons see in these graphs.

If you want to spit hairs, and it is mentioned on SubsTech's website, you can optimize a bearing clearance to take advantage of the peak MOFT it will develop. But again, that doesn't mean that thicker oil in those bearings doesn't give more MOFT compared to thinner oil, because regardless of the bearing clearance, thicker oil will always make more MOFT with all the other bearing factors held constant. Go read the SubsTech website and learn how journal bearings work ... it's all there. I'm not going to keep repeating all this tech info to you over and over until the light bulb comes on ... at this point you're gonna have to do it for yourself since you don't seem to believe it in this thread discussion. Also go search around on BITOG ... this stuff has been hashed out for years and there are probably 100+ theads about it all. Hoperfully some other people reading this stuff absorbed some knowledge on journal bearings.