Does fuel lubricate upper cylinder/piston rings?
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In a diesel probably yes. In a gas engine, i don't think so.
A related question: How is it possible rings and upper cylinder walls don't wear much faster than they do? That they don't still amazes me, especially in non-oil-guzzlers. The amount of oil that makes it all the way up there is extremely small, the relative speed at the top is too slow to maintain a hydrodynamic wedge, and the trace of oil up there is subject to extreme temperatures, besides. Yet, somehow, my Mazda had practically no ridge at the top of the cylinders at 476402 miles.
Cylinders have 3 types of wear: Ring wear, taper wear, and out of round wear. Ring wear affects the top cm of the cylinder
Originally Posted by CR94
A related question: How is it possible rings and upper cylinder walls don't wear much faster than they do? That they don't still amazes me, especially in non-oil-guzzlers. The amount of oil that makes it all the way up there is extremely small, the relative speed at the top is too slow to maintain a hydrodynamic wedge, and the trace of oil up there is subject to extreme temperatures, besides. Yet, somehow, my Mazda had practically no ridge at the top of the cylinders at 476402 miles.
I can't say for sure, but i think there is a good bit of oil between the top and middle ring that keeps the top of the cyl lubricated.
A related question: How is it possible rings and upper cylinder walls don't wear much faster than they do? That they don't still amazes me, especially in non-oil-guzzlers. The amount of oil that makes it all the way up there is extremely small, the relative speed at the top is too slow to maintain a hydrodynamic wedge, and the trace of oil up there is subject to extreme temperatures, besides. Yet, somehow, my Mazda had practically no ridge at the top of the cylinders at 476402 miles.
I can't say for sure, but i think there is a good bit of oil between the top and middle ring that keeps the top of the cyl lubricated.
All engines use oil to some degree it's just that it's not perceivable on our dipsticks over the course of an OCI for most folks but there is some minute amounts of oil slipping past the rings into the combustion chamber in every engine with every stroke.
There is also lubricants added to fuels but more so they don't have a corrosive effect throughout your fuel system (as I understand it). I'm sure this might also help as it gets sprayed into the cylinder but not to the degree engine oil would and certainly not when the engine is running extremely rich where the fuel is washing the cylinder walls of the thin coating of oil.
There is also lubricants added to fuels but more so they don't have a corrosive effect throughout your fuel system (as I understand it). I'm sure this might also help as it gets sprayed into the cylinder but not to the degree engine oil would and certainly not when the engine is running extremely rich where the fuel is washing the cylinder walls of the thin coating of oil.
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in the late 60s. in my automotive class we had a factory rep from Perfect Circle give a lecture on how the rings work. he told how small changes in the angle on the face of a ring made a big effect on how much oil the engine uses. and the proper finish on the cylinder wall is very important on how the rings work. and how the cyl wall holds a small amount of oil. IMHO gasoline has very close to zero lubrication. thats why i use MMO. of course you knew that .
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I don't know for sure but I suspect, fuel DOES play a largely unrecognised role in top ring lubrication.
To understand why, you need to know that most modern gasolines contain a cocktail of 'performance' additives & that most of these additives have their roots in the lubricant additives business.
The primary additive in fuel is something Fuels people annoying refer to as Detergent. This has nothing to do with the overbased metallic detergents you get in oil but is very like the polymeric ashless dispersants Oily people like me use to combat piston deposits & sludge. In addition, you'll find both Phenolic & Amine based antioxidants in gasoline, both of which have been used in lubes for donkey's years. It's been 25 years since I last dabbled in fuel additives but back then, it was also the norm to mate up the additive components with a 'carrier oil', typically a heavy 500SN base oil.
I have often pondered on what happens to these additives in the combustion chamber. Compared to the light hydrocarbons that are native to gasoline, the additives are all relatively heavy (especially the ashless dispersant & carrier oil). Do they burn? Given that gasoline burns are so rapid, I suspect not. If they don't burn, where do they go? Might they, as heavy liquid particles get swirled out towards the relatively cold cylinder walls & condense? It's possible. If so, are you in effect depositing a 'perfect' layer of non-volatile, heavy oil on the wall to lubricate the top ring on it's upward stroke? It sort of makes sense to me!
To understand why, you need to know that most modern gasolines contain a cocktail of 'performance' additives & that most of these additives have their roots in the lubricant additives business.
The primary additive in fuel is something Fuels people annoying refer to as Detergent. This has nothing to do with the overbased metallic detergents you get in oil but is very like the polymeric ashless dispersants Oily people like me use to combat piston deposits & sludge. In addition, you'll find both Phenolic & Amine based antioxidants in gasoline, both of which have been used in lubes for donkey's years. It's been 25 years since I last dabbled in fuel additives but back then, it was also the norm to mate up the additive components with a 'carrier oil', typically a heavy 500SN base oil.
I have often pondered on what happens to these additives in the combustion chamber. Compared to the light hydrocarbons that are native to gasoline, the additives are all relatively heavy (especially the ashless dispersant & carrier oil). Do they burn? Given that gasoline burns are so rapid, I suspect not. If they don't burn, where do they go? Might they, as heavy liquid particles get swirled out towards the relatively cold cylinder walls & condense? It's possible. If so, are you in effect depositing a 'perfect' layer of non-volatile, heavy oil on the wall to lubricate the top ring on it's upward stroke? It sort of makes sense to me!
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The top ring is largely lubricated by the engine oil.
There's plenty of papers that show hydrodynamic lubrication mid stroke. A few that show that as the oil goes, away, the remnant is very heavily additised (good for the boundary stuff at end of stroke).
However,I've also seen a few papers showing demonstrably that certain FMs added to fuel make a serious difference to ring/liner wear.
So yes, and also it depends
There's plenty of papers that show hydrodynamic lubrication mid stroke. A few that show that as the oil goes, away, the remnant is very heavily additised (good for the boundary stuff at end of stroke).
However,I've also seen a few papers showing demonstrably that certain FMs added to fuel make a serious difference to ring/liner wear.
So yes, and also it depends
Originally Posted by Shannow
However,I've also seen a few papers showing demonstrably that certain FMs added to fuel make a serious difference to ring/liner wear.
So yes, and also it depends
HMM which FM's ? That would be cool to add to fuel. Any relation to TCW-3 adds?
However,I've also seen a few papers showing demonstrably that certain FMs added to fuel make a serious difference to ring/liner wear.
So yes, and also it depends
HMM which FM's ? That would be cool to add to fuel. Any relation to TCW-3 adds?
A believe in 4 cycle engines that engine oil is squirted or splashed up into the cylinder walls on the underside of the piston.
There are allegedly proprietary solid lubricants That can add top cylinder lubrication.
UCL = Scamorama in modern engines.
Originally Posted by red7404
in the late 60s. in my automotive class we had a factory rep from Perfect Circle give a lecture on how the rings work. he told how small changes in the angle on the face of a ring made a big effect on how much oil the engine uses. and the proper finish on the cylinder wall is very important on how the rings work. and how the cyl wall holds a small amount of oil. IMHO gasoline has very close to zero lubrication. thats why i use MMO. of course you knew that .
Most people don't know the context.
In the 1960s Perfect Circle was a well-known brand of pre-made piston rings. They were competing against shop-made rings, which a few old-timers still preferred.
Shop-made rings were made on-site, as needed, from steel or cast iron pipe. Piston rings would be cut on a lathe to match the engine. They would be slit and the ends filed to the proper gap. They relied heavily on a break-in period, wearing down to smooth the surfaces and square the edges. Perfect Circle's marketing pitch was that their rings were more accurately made, and that this had a big impact on performance.
This is also why honing a cylinder used to be critical. The honed cylinder surface acted like a metal file to square the ring edges and even out the pressure. If all went well the cylinder's sharp edges were worn down to oil-retaining grooves just as the rings were machined to shape. Otherwise the rings either wouldn't "seat" (be worn down to a square edge) or would be over-worn and have their service life considerably shortened.
Even factory made rings of the era required some break-in, so they weren't nearly as Perfect as their marketing suggested.
in the late 60s. in my automotive class we had a factory rep from Perfect Circle give a lecture on how the rings work. he told how small changes in the angle on the face of a ring made a big effect on how much oil the engine uses. and the proper finish on the cylinder wall is very important on how the rings work. and how the cyl wall holds a small amount of oil. IMHO gasoline has very close to zero lubrication. thats why i use MMO. of course you knew that .
Most people don't know the context.
In the 1960s Perfect Circle was a well-known brand of pre-made piston rings. They were competing against shop-made rings, which a few old-timers still preferred.
Shop-made rings were made on-site, as needed, from steel or cast iron pipe. Piston rings would be cut on a lathe to match the engine. They would be slit and the ends filed to the proper gap. They relied heavily on a break-in period, wearing down to smooth the surfaces and square the edges. Perfect Circle's marketing pitch was that their rings were more accurately made, and that this had a big impact on performance.
This is also why honing a cylinder used to be critical. The honed cylinder surface acted like a metal file to square the ring edges and even out the pressure. If all went well the cylinder's sharp edges were worn down to oil-retaining grooves just as the rings were machined to shape. Otherwise the rings either wouldn't "seat" (be worn down to a square edge) or would be over-worn and have their service life considerably shortened.
Even factory made rings of the era required some break-in, so they weren't nearly as Perfect as their marketing suggested.
Of course fuel does. How could it not?
Proof Look at excessive cyl wear in MD engines.
Proof Look at excessive cyl wear in MD engines.
Originally Posted by StevieC
All engines use oil to some degree it's just that it's not perceivable on our dipsticks over the course of an OCI for most folks but there is some minute amounts of oil slipping past the rings into the combustion chamber in every engine with every stroke.
There is also lubricants added to fuels but more so they don't have a corrosive effect throughout your fuel system (as I understand it). I'm sure this might also help as it gets sprayed into the cylinder but not to the degree engine oil would and certainly not when the engine is running extremely rich where the fuel is washing the cylinder walls of the thin coating of oil.
This touches on the major issue in my mind . Gasoline would / does have a negative effect on what ever amount of oil is on the cylinder walls . " Washing " it off .
Gas is more of a solvent than a lubricant .
At least that is what I have always been told / read . I have also been told that one of the reasons newer FI engines last longer than the older carburated engines if the FI give a better / more precise / accurate fuel / air mixture .
All engines use oil to some degree it's just that it's not perceivable on our dipsticks over the course of an OCI for most folks but there is some minute amounts of oil slipping past the rings into the combustion chamber in every engine with every stroke.
There is also lubricants added to fuels but more so they don't have a corrosive effect throughout your fuel system (as I understand it). I'm sure this might also help as it gets sprayed into the cylinder but not to the degree engine oil would and certainly not when the engine is running extremely rich where the fuel is washing the cylinder walls of the thin coating of oil.
This touches on the major issue in my mind . Gasoline would / does have a negative effect on what ever amount of oil is on the cylinder walls . " Washing " it off .
Gas is more of a solvent than a lubricant .
At least that is what I have always been told / read . I have also been told that one of the reasons newer FI engines last longer than the older carburated engines if the FI give a better / more precise / accurate fuel / air mixture .
If lubrication by gasoline (or additives in it) plays a significant role in minimizing upper-cylinder wear, how can engines fueled by natural gas last as long as they do?
So to recap:
-full formula engine oil: effective lubrication
-fuel-delivered lubricants: effective lubrication
-gasoline: ineffective lubrication
-excess gasoline washing: wear-promoting
?
-full formula engine oil: effective lubrication
-fuel-delivered lubricants: effective lubrication
-gasoline: ineffective lubrication
-excess gasoline washing: wear-promoting
?
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