Originally Posted By: fsskier
Pressure is not flow!!
Someone mentioned the test we used to do on motors to test bearings, chunking up the distributor shaft with an electric drill
(thus spinning the oil pump) and looking at the crankshaft bearings with the pan off. Even with lots of pressure, virtually no oil flows through that .002 bearing clearance when:
the oil is cold and you have good bearings.
Well, it's not exactly designed to flow through the bearing when stationary, it's meant to be fed under pressure while the crank is rotating and letting the bearing rotation pump it through via the wedge that builds up.
Originally Posted By: fsskier
Now, according to the big GM/Mobil/others study that was published in the SAE journal around 1980, the cylinder walls are starved for oil for a long time after startup with thicker oils in cold temperatures. When hot the situation changes from "a drop of oil every once in a while" to a continous shower of oil.
That study was the forerunner of the switch from 10wXXX oils to 5Wxxx oils. Their test results showed that cylinder wall wear was clearly much less with 5wXX oils, then with 10Wxx oils during the first 3 miles of operation - and that the bearings themselves were uneffected either way.
It hasn't been proven that the extra wear is from extra clearance when cold or oil starvation. Yours sounds like a fairly sound argument and I can only assume it's both. I wish I could find that old test where the straight weight killed the rest. If I didn't live in such a mild climate, I wouldn't run a straight 30 but I have confidence that I will have less wear and deposits with it or I wouldn't run it. Only time will tell.
Originally Posted By: fsskier
Those old enough to have done a lot of machine shop work in the 70's will remember that Ford attempted to save money by eliminating the little "squirter" drill hole in the top side of the rods big end. That resulted in thousands of engines being rebuilt in the north by Ford, under warranty due to extreme cylinder wall wear and scoring. (many at about 35,000 miles) This problem did not occur in the south at all!!! Note that those engines would have had plenty of pressure, but little flow, with cold thick oil in wintertime. I personally witnessed a 460 CI Lincoln continental, a 200 CI maverick and a pair of 2300 CC Pintos, all paid for by Ford under warranty. (The undrilled rods were always replaced when doing warranty work)
And, enhancing my paycheck.......
I'm not sure how Ford dropped the ball on this one. I can only assume they used the same rods but without the hole and kept the same side clearances on the rod to crank causing oil starvation. The majority of engines don't have squirters. Again, that's an assumption.
Originally Posted By: fsskier
As you can see, arguments that center around how fast the pressure comes up are meaninless. Only flow counts - for the cylinder walls.
The reason I mention time to pressure is for some of the posters that think oil doesn't flow at all when cold or it takes 20 minutes to get prssure while the engine grinds itself to death. I agree that flow is what counts for the cylinders. Depending on engine design oil can come from the valley area and drain onto the spinning crank. My GN is one of these that dumps oil on the crank from the lifters.
Originally Posted By: fsskier
Some motors, like BUICKGN's 3.8 get lots of flow from the rod bearings due to their tortured crankshaft design and GM I believe always recommended 10Wxx oils in them. And many Turbo models have additional oil sprayed up to cool the piston bottoms, perhaps Buick can give us additional information about the 3.8's peculiar oil requirements.
I wish we had piston oil squrters. Crank, rods, block, and even head castings are all standard NA parts. Only pistons are specific to the turbo models. The crank differed in the way that it was machined with the rod fillets rolled instead of just the mains. I know when setting one of these things up it's a fine balance between cylinder wall starvation and too low of oil pressure when setting up the side clearance on rods. The poor little cast crank, it looks like it would break if you look at it wrong. You can imagine my stress level every time I open it up. It's just a matter of time...
Pressure is not flow!!
Someone mentioned the test we used to do on motors to test bearings, chunking up the distributor shaft with an electric drill
(thus spinning the oil pump) and looking at the crankshaft bearings with the pan off. Even with lots of pressure, virtually no oil flows through that .002 bearing clearance when:
the oil is cold and you have good bearings.
Well, it's not exactly designed to flow through the bearing when stationary, it's meant to be fed under pressure while the crank is rotating and letting the bearing rotation pump it through via the wedge that builds up.
Originally Posted By: fsskier
Now, according to the big GM/Mobil/others study that was published in the SAE journal around 1980, the cylinder walls are starved for oil for a long time after startup with thicker oils in cold temperatures. When hot the situation changes from "a drop of oil every once in a while" to a continous shower of oil.
That study was the forerunner of the switch from 10wXXX oils to 5Wxxx oils. Their test results showed that cylinder wall wear was clearly much less with 5wXX oils, then with 10Wxx oils during the first 3 miles of operation - and that the bearings themselves were uneffected either way.
It hasn't been proven that the extra wear is from extra clearance when cold or oil starvation. Yours sounds like a fairly sound argument and I can only assume it's both. I wish I could find that old test where the straight weight killed the rest. If I didn't live in such a mild climate, I wouldn't run a straight 30 but I have confidence that I will have less wear and deposits with it or I wouldn't run it. Only time will tell.
Originally Posted By: fsskier
Those old enough to have done a lot of machine shop work in the 70's will remember that Ford attempted to save money by eliminating the little "squirter" drill hole in the top side of the rods big end. That resulted in thousands of engines being rebuilt in the north by Ford, under warranty due to extreme cylinder wall wear and scoring. (many at about 35,000 miles) This problem did not occur in the south at all!!! Note that those engines would have had plenty of pressure, but little flow, with cold thick oil in wintertime. I personally witnessed a 460 CI Lincoln continental, a 200 CI maverick and a pair of 2300 CC Pintos, all paid for by Ford under warranty. (The undrilled rods were always replaced when doing warranty work)
And, enhancing my paycheck.......
I'm not sure how Ford dropped the ball on this one. I can only assume they used the same rods but without the hole and kept the same side clearances on the rod to crank causing oil starvation. The majority of engines don't have squirters. Again, that's an assumption.
Originally Posted By: fsskier
As you can see, arguments that center around how fast the pressure comes up are meaninless. Only flow counts - for the cylinder walls.
The reason I mention time to pressure is for some of the posters that think oil doesn't flow at all when cold or it takes 20 minutes to get prssure while the engine grinds itself to death. I agree that flow is what counts for the cylinders. Depending on engine design oil can come from the valley area and drain onto the spinning crank. My GN is one of these that dumps oil on the crank from the lifters.
Originally Posted By: fsskier
Some motors, like BUICKGN's 3.8 get lots of flow from the rod bearings due to their tortured crankshaft design and GM I believe always recommended 10Wxx oils in them. And many Turbo models have additional oil sprayed up to cool the piston bottoms, perhaps Buick can give us additional information about the 3.8's peculiar oil requirements.
I wish we had piston oil squrters. Crank, rods, block, and even head castings are all standard NA parts. Only pistons are specific to the turbo models. The crank differed in the way that it was machined with the rod fillets rolled instead of just the mains. I know when setting one of these things up it's a fine balance between cylinder wall starvation and too low of oil pressure when setting up the side clearance on rods. The poor little cast crank, it looks like it would break if you look at it wrong. You can imagine my stress level every time I open it up. It's just a matter of time...
