[Tom Vaught]

Originally Posted by RAIV-Z

There are 2 holes in each upper bearing shell.

If it was one hole and moved to the lower position then maybe in my mind they might have tried to hit the "Optimal Location" position mentioned in the CAMSHAFT oil feed illustration.

With both holes open it would seem to me that the lower hole would be blocking some of the oil flow from the upper hole.

Course you do not know which hole is "winning" that battle but you do know that there is high pressure oil pushing on the backside of the main bearing die to the 3/8" x 1/5" groove.

Like I said you have lots of oil going thru the normal hole to the grooved upper bearing.

So that Racing Mod is a "Mystery" to me from the fluids standpoint, maybe Eric "Boss Bird" has seen that mod on aircraft engines.

Tom Vaught

[Elarson]

Originally Posted by Tom Vaught

If it was one hole and moved to the lower position then maybe in my mind they might have tried to hit the "Optimal Location" position mentioned in the CAMSHAFT oil feed illustration.

With both holes open it would seem to me that the lower hole would be blocking some of the oil flow from the upper hole.

Course you do not know which hole is "winning" that battle but you do know that there is high pressure oil pushing on the backside of the main bearing die to the 3/8" x 1/5" groove.

Like I said you have lots of oil going thru the normal hole to the grooved upper bearing.

So that Racing Mod is a "Mystery" to me from the fluids standpoint, maybe Eric "Boss Bird" has seen that mod on aircraft engines.

Tom Vaught

Aircraft turbine engines only use rolling element bearings; not journal bearings.....so the oiling scheme is totally different.

The peak loads on the main bearings will be roughly at (4) locations aligned with the up and down forces from each cylinder bank. The loads on the top half of the bearing will be most heavily influenced by rpm and weight of reciprocating parts. The load on the bottom shell is influenced by cylinder pressure, rpm and weight of recip parts. So it's important to flood all quadrants of the bearing with oil. The grooved upper bearing half helps distribute oil to the lower half.

It would be interesting to hear from the creator of this mod about the reasoning. Just guessing.....Perhaps it's needed for a super stock engine with thin oil and low pressure?

We've never done that on either of our cars.

Eric