Check this out.. I was reading Sport Compact car Mag, April on page 244, they have a section on dry sump. (A dry sump is a lubrication system in which engine oil is held and pumped from an external tank, rather than from an engine's oil pan.) Well my theory is that when oil in our pans splashes around it misses the oil pump tube, this allowing the car to have oil starvation. Because of this oil starvation you will start eating into your crank and eventually get crank walk. That might explain why auto X'er get crank walk before a drag racer. I really think that the oil galleries in our engine are very bad and small so they can clog or not support enough oil to the bearings. This article really helps prove this theory. Let me know what you guys think? But I don't think that switching to a dry sump will eliminator or cure crank walk, but it would sure help. Not to mention all the benefits of having this type of system.
awdboost
well, i have to say i disagree and agree with this.
first, the part i agree with is the oil galleries are small in our engines, and not designed very well. especially as it relates to the squirter set up and locations around the crankshaft.
i disagree with the theory about the oil pan and the dry sump. think about it like this: our engines hold 4+ quarts of oil. at any given time with engine running, there is probably at most 1.5 quarts in the engine itself, and most of that is actually either in the pump or runnin through the oil passages, or in in the filter assembly. so on the average there is probably 2+ quarts sitting in the oil pan (ok- so not really "sitting" but circulating through it). and on our oil pans, on the lowest side where it dips down is where the oil pickup tube is. this tube is really close to the bottom of the pan. and also, there is a metal plate that covers this section of the pan for this exact reason. it does have a big opening in the top so the tube can fit through, but its purpose it to prevent oil starvation. so unless you are really low on oil (which definately isnt good at preventing crank walk), you really shouldnt have to worry unless you are driving on a road with a 40 degree bank.
but i will say this to support your theory (or maybe start a new one): the oil pickup tubes on the 1g 6 bolt engines have an almost completely flat screen on the end with a diameter of about 4 inches. this allows them to get much further down into the oil level preventing it from sucking air instead of oil. it creates a much better suction by remaining completely submerged in oil. the 2g pickup tubes have a screen that looks like half a sphere - with a diameter of maybe 3 inches. so if you think about it, if the oil is not completely covering that entire sphere, the pump would be sucking up air. and since air is much less dense than oil, it probably wont pick up much oil at all - its like trying to drink through a straw that has a crack in the side - nothing but air. so the 2g's are probably much less forgiving of lower oil levels that 1gs, thats for sure. but honestly there is never going to be any one cause to blame CW on.
just my 2 cents.
first, the part i agree with is the oil galleries are small in our engines, and not designed very well. especially as it relates to the squirter set up and locations around the crankshaft.
i disagree with the theory about the oil pan and the dry sump. think about it like this: our engines hold 4+ quarts of oil. at any given time with engine running, there is probably at most 1.5 quarts in the engine itself, and most of that is actually either in the pump or runnin through the oil passages, or in in the filter assembly. so on the average there is probably 2+ quarts sitting in the oil pan (ok- so not really "sitting" but circulating through it). and on our oil pans, on the lowest side where it dips down is where the oil pickup tube is. this tube is really close to the bottom of the pan. and also, there is a metal plate that covers this section of the pan for this exact reason. it does have a big opening in the top so the tube can fit through, but its purpose it to prevent oil starvation. so unless you are really low on oil (which definately isnt good at preventing crank walk), you really shouldnt have to worry unless you are driving on a road with a 40 degree bank.
but i will say this to support your theory (or maybe start a new one): the oil pickup tubes on the 1g 6 bolt engines have an almost completely flat screen on the end with a diameter of about 4 inches. this allows them to get much further down into the oil level preventing it from sucking air instead of oil. it creates a much better suction by remaining completely submerged in oil. the 2g pickup tubes have a screen that looks like half a sphere - with a diameter of maybe 3 inches. so if you think about it, if the oil is not completely covering that entire sphere, the pump would be sucking up air. and since air is much less dense than oil, it probably wont pick up much oil at all - its like trying to drink through a straw that has a crack in the side - nothing but air. so the 2g's are probably much less forgiving of lower oil levels that 1gs, thats for sure. but honestly there is never going to be any one cause to blame CW on.
just my 2 cents.
Yeah, I dont think Sport Compact really knows too much...
Last I heard from the higher ups, was that it was based on the oil squirters for the pistons, they get stuck open and squirt at idle, which is when pressure is lowest, and lower it even more. Low oil pressure on bearings gets lower, less oil... That's what I thought it was about, I'll agree that the galleries being poor and all, but what about attempts to stop CW? What has been done? Blocking squirters, replacing them with 1g ones, swiss cheese thrust bearings, and retooling galleries. Just from what I've heard from the dsm hardcores...
Last I heard from the higher ups, was that it was based on the oil squirters for the pistons, they get stuck open and squirt at idle, which is when pressure is lowest, and lower it even more. Low oil pressure on bearings gets lower, less oil... That's what I thought it was about, I'll agree that the galleries being poor and all, but what about attempts to stop CW? What has been done? Blocking squirters, replacing them with 1g ones, swiss cheese thrust bearings, and retooling galleries. Just from what I've heard from the dsm hardcores...
Sorry this is off topic, but: 
Sport Compact doesn't know that much!!??? I have never read another car magazine where the writers had more technical knowledge about what they were writing. Have you ever read Dave Coleman's section, Technobabble? You want to see a mag that doesn't know much , pick up a copy of Super Street. Those guys are boneheads. One time they took an artical about Mazda's Rotary from SCC and copied it word-for-word in their mag. It was the only smart thing I've seen thmem write. Sorry, just had to vent.
Sport Compact doesn't know that much!!??? I have never read another car magazine where the writers had more technical knowledge about what they were writing. Have you ever read Dave Coleman's section, Technobabble? You want to see a mag that doesn't know much , pick up a copy of Super Street. Those guys are boneheads. One time they took an artical about Mazda's Rotary from SCC and copied it word-for-word in their mag. It was the only smart thing I've seen thmem write. Sorry, just had to vent.awdboost said:
Well that's a well founded thought.
Where is your data? Are you saying that all the 2G's that have come down with a preworn thrust bearing are autocrossers? Statements like this just add to the confusion.If you really want to ponder crankwalk for a solution, start from the inside out, not the outside in. What I mean is don't take a probable cause and narrow it down the point of failure. Start at the point of failure and work your way out. In this case (crankwalk) point of failure is simple:
The crank invades the oil film of the thrust bearing and contacts the thrust bearing face.
There. Start from there and work out. Ask simple questions? Why does the crank move? Why does the film not resist the crank? Why does the crank penetrate the film?
What you will get is a list of possible root causes. Then its a matter of exploring each option of likely candidates.
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