Help Solve the Myth!

[Alky V6]

The 10 psi per 1000 rpm is from the Buick "folklore".

Actually, It's more than Buick folklore. I've seen that same rule of thumb published in various books.

 

[sailbrd]

We go over this a lot on the big block Buicks. On the BBB's it is not hi volume oil pumps are generally NOT recomended. They are only recommended on race motors with "loose" clearances. Also bronze gears should be used.

The other thing is to not use anything but the stock "black" relief spring in the oil pump (warning from TA.)

I have had two motors, one a 455 that has the hi volumn pump and had no problems. This is my original motor and is on the stand now to be freshened. The new motor is blueprinted with a booster plate only and has great oil pressure with no problems. Guess I am lucky on both motors.

 

[Jerryl]

Guess that answers some of the concerns/questions.Thanks for the responses.

 

[Blown&Injected]

The 10 psi per 1000 rpm is from the Buick "folklore". It actually depends on the diameter of the crank, since the centrifugal force varies with the radius. Bigger cranks may require more than 10 psi per 1000 rpm. The journal bearings are "hydrodynamic", in that the turning crank provides the pressure once the oil actually gets where it is needed- oil pump pressure is no longer involved. That's true in top fuel, and in an econobox.
One issue with higher pressure on the Buicks can be side clearance between the rods. That dimension, along with rod bearing clearance, controls flow that splashes onto the cylinder walls. Years ago, you could get new rods that were "thicker" than stock, to let you set that clearance tight, if you wanted to. Now, that dimension may be too big, and with a high volume pump, you might get more oil on the cyldinder walls than the rings can handle. Seems possible, anyway.

VERY INTERESTING...I would really like to hear more about this. Sorry about all the questions, just trying to get it all figured out.

So do you mean the rod journals are not directly fed by the pump? It seems that the main journals get the pressure from the pump but after entering the crank it seems like the spin would force the oil towards the rods, so what force would the oil, driven by the pump, need to overcome and just where does it hit that point?

Also, just thinking as I am going here, if the oil pump is not what is keeping pressure on the crank journals, it sounds like the oil pressure is not determined by the clearance in those journals. Is the oil pressure determined by the clearances in the cam and lifter area?

Thinking about all this makes me wonder how much oil pours out from around the cam (the first leak?), the lifters, the crank/rods, and how much makes it to the top end.