Quote:
Originally Posted by "QUICK-SILVER"
Given same bearing clearance and oil pressure.....how much more oil comes out when rod side clearance goes from .020" to say .030"?
I don't how it could make a difference
Clay
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Formula for circumference of a circle (as the oil "leaks" around the entire rod journal past the bearing): C=2 x Pi x R
So say we use "easy math" on a big block chevy rod journal (2.20")
(Pontiac Rod journal is .050" bigger and will leak more.)
Radius = 1/2 of the rod diameter so 2.20" divided by 2 = 1.10" (easy math)
Pi = 3.1416
The Number 2 is obvious.
Everyone knows that the circumference of a 4" pipe is 12.566 inches.
Plug it into the formula and you will see the formula gives the correct answer.
So now we do the single BB Chevy rod journal 2.20" in diameter
1/2 of 2.2" = 1.1" or the RADIUS
We already know Pi is 3.1416
2 is a simple number to multiply the numbers above.
So 1.1 x 3.1416 x 2 = 6.91152 TIMES .020" clearance = .1382304" (a .020" wide oil leak around the rod journal).
1.1 x 3.1416 x 2 = 6.91152 TIMES .030" clearance = .2073456" (a .030" wide oil leak around the rod journal).
.1382304" times 150% = .2073456" so the .030" wide Rod clearance leaks 50% more oil vs the .020" rod side clearance. Bet a bit more than you thought, huh, Clay as far as cooling of the bearing goes. Been doing this stuff for years. Simple math does not lie.
That would be the difference in a simple experiment but as I said the rods move and constantly change the value when in motion BUT
it does answer your basic question.
Tom V.