Gary Allan : Wow I didn't know you could put THOSE in an engine!!! UOA?
Kind of like this link to articlequote:
Originally posted by Rickey:
Gary Allan: All I am trying to point out here is that there are some fundamental physical properties regarding viscosity in a bearing and that thinner is not always better. To wit: a thicker oil cushion will always offer better protection from oil bourne debris. Now if you don't believe that just go argue with a stop sign.
Well, let's take a look at their reasoning here..quote:
Originally posted by Hirev:
Kind of like this link to articlequote:
Originally posted by Rickey:
Gary Allan: All I am trying to point out here is that there are some fundamental physical properties regarding viscosity in a bearing and that thinner is not always better. To wit: a thicker oil cushion will always offer better protection from oil bourne debris. Now if you don't believe that just go argue with a stop sign.
Lets talk about your analogy for a minute. Which would you rather have between you and a raging fire sir? 1/2 inch of drywall or three feet of concrete?quote:
Originally posted by Gary Allan:
well, lets for the moment go with your theory ..call it fact.
..and 3 ft of concrete will resist fire longer then 2 ft, right. But you only need 1/2" drywall for a 2 hour firewall.
I'll connect the dots, if necessary.
I knew thatquote:
Originally posted by Ray H:
30% is absurd. (Even an idiot knows it's just a hair over 29.99999999999999999%.)
Except that's not correct. There would be no wedge if the journal were centered in the bearing. The journal has to run off center for the wedge to form and viscosity has an effect on how far off center it runs and how thick the film thickness is on the loaded side.quote:
Originally posted by Bryanccfshr:
Rickey. Did you read Bruces's post about formation of the oil wedge and thicknes of the wedge?.
The thickness of the wedge is not influenced by viscosity, only the speed of the rotating parts and surface area combined with viscosity can influence the time at wich the wedge is formed. The hydrodynamic wedge is going to fill the spaces between the Two pieces and that does not changewith viscosity. Do you understand the pyhsical limitations? You cannot get a thicker film in a wedgeunless the other side of the bearing is open alowing the roating part to move away from the wedge. That would be a journal bearing without a cap for example.
If there is enough oil supplied to the bearing to keep it full then it is protected.
So, Doc Haas, in this scenario (and I assume the lack of rebuttal thus far indicates no disagreement with the scenario), which vis would minimize the effect of the wedge and the wear it creates? A 5W20, or 5W30? I'm going to assume a scenario where the oil is warmed up, but perhaps it would apply in greater fashion to a cold engine? Also, does this scenario apply to normal street cars of average performance?quote:
The journal is always off center in an automotive application when under load. There is a pressure wave or wedge at one end and yes it is larger for a greater viscosity. Oil at the wedge can also act as a solid under extreme pressure, thick or thin. This itself may cause chunks of bearing material to be released. On the other end of the wedge there may be a vacuum and therefore cavitation. This may cause chunks of bearing material to be released. This is known to be the most damaging to bearings.
What about side leakage? (Caution hypothetical sarcasm ahead) Oh darn there I need a bigger oil pump and tighter bearings for that 2Cst oil I just put in! But I did increase engine efficency by .05 percentquote:
Originally posted by Bryanccfshr:
Rickey. Did you read Bruces's post about formation of the oil wedge and thicknes of the wedge?.
The thickness of the wedge is not influenced by viscosity, only the speed of the rotating parts and surface area combined with viscosity can influence the time at wich the wedge is formed. The hydrodynamic wedge is going to fill the spaces between the Two pieces and that does not changewith viscosity. Do you understand the pyhsical limitations? You cannot get a thicker film in a wedgeunless the other side of the bearing is open alowing the roating part to move away from the wedge. That would be a journal bearing without a cap for example.
If there is enough oil supplied to the bearing to keep it full then it is protected.