Do the rings make contact with a cylindar wall as a motor is running? Or is there a thin layer of oil between the rings and the cylinder wall? If the rings do not make contact how close do the rings get? As thin as a human hair or less?
Rings & cylindar walls?
- Thread starter Camprunner
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They do end up making contact. Oil helps a little but isn’t perfect. Rings are coated or made of hard material to help lessen wear.
I think they make some contact. But for the most part ride on an oil film. I tend to believe there is less ring to cylinder contact on a bore that has had a 2 step plateau hone as this holds more oil. Moly faced rings had a reputation for holding more oil, i don't know it thats true.
In the 70's-80's most high mileage engines would have a ridge at the top of the cylinder making it difficult to remove the pistons. You don't really see that anymore. Better oil and better cnc machining and honing. Probably better( faster) engine warmup and temperature control as well helps.
In the 70's-80's most high mileage engines would have a ridge at the top of the cylinder making it difficult to remove the pistons. You don't really see that anymore. Better oil and better cnc machining and honing. Probably better( faster) engine warmup and temperature control as well helps.
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They can't touch by much, if hardly ever.
My 1993 Ford Ranger has ~290,000 miles on it. Still runs well.
Cruise on the highway is about 2700 RPM.
Pistons stroke twice per 1 full rev, so 5400 swipes per minute at 2700 RPM.
5400 swipes per min = 324,000 swipes per hour.
If I average 50 MPH, that's been about 5800 hours, or 1,879,200,000 (1.879 to the 9th power)
Yeah.... I really don't think they make contact all that often.
My 1993 Ford Ranger has ~290,000 miles on it. Still runs well.
Cruise on the highway is about 2700 RPM.
Pistons stroke twice per 1 full rev, so 5400 swipes per minute at 2700 RPM.
5400 swipes per min = 324,000 swipes per hour.
If I average 50 MPH, that's been about 5800 hours, or 1,879,200,000 (1.879 to the 9th power)
Yeah.... I really don't think they make contact all that often.
Originally Posted By: spasm3
I think they make some contact. But for the most part ride on an oil film. I tend to believe there is less ring to cylinder contact on a bore that has had a 2 step plateau hone as this holds more oil. Moly faced rings had a reputation for holding more oil, i don't know it thats true.
In the 70's-80's most high mileage engines would have a ridge at the top of the cylinder making it difficult to remove the pistons. You don't really see that anymore. Better oil and better cnc machining and honing. Probably better( faster) engine warmup and temperature control as well helps.
Thus the need for a ridge reamer. My Dad had one.
I think they make some contact. But for the most part ride on an oil film. I tend to believe there is less ring to cylinder contact on a bore that has had a 2 step plateau hone as this holds more oil. Moly faced rings had a reputation for holding more oil, i don't know it thats true.
In the 70's-80's most high mileage engines would have a ridge at the top of the cylinder making it difficult to remove the pistons. You don't really see that anymore. Better oil and better cnc machining and honing. Probably better( faster) engine warmup and temperature control as well helps.
Thus the need for a ridge reamer. My Dad had one.
Originally Posted By: Donald
Originally Posted By: spasm3
I think they make some contact. But for the most part ride on an oil film. I tend to believe there is less ring to cylinder contact on a bore that has had a 2 step plateau hone as this holds more oil. Moly faced rings had a reputation for holding more oil, i don't know it thats true.
In the 70's-80's most high mileage engines would have a ridge at the top of the cylinder making it difficult to remove the pistons. You don't really see that anymore. Better oil and better cnc machining and honing. Probably better( faster) engine warmup and temperature control as well helps.
Thus the need for a ridge reamer. My Dad had one.
And if you were not careful, you could really screw up a bore using a ridge reamer.
Originally Posted By: spasm3
I think they make some contact. But for the most part ride on an oil film. I tend to believe there is less ring to cylinder contact on a bore that has had a 2 step plateau hone as this holds more oil. Moly faced rings had a reputation for holding more oil, i don't know it thats true.
In the 70's-80's most high mileage engines would have a ridge at the top of the cylinder making it difficult to remove the pistons. You don't really see that anymore. Better oil and better cnc machining and honing. Probably better( faster) engine warmup and temperature control as well helps.
Thus the need for a ridge reamer. My Dad had one.
And if you were not careful, you could really screw up a bore using a ridge reamer.
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Originally Posted By: Camprunner
Do the rings make contact with a cylindar wall as a motor is running? Or is there a thin layer of oil between the rings and the cylindar wall? If the rings do not make contact how close do the rings get? As thin as a human hair or less?
Put some oil on your finger tips and rub them together, that is how close the rings are to the cylinder wall. If a human hair would fit between the rings and cylinder you would have the wrong size pistons installed.
Do the rings make contact with a cylindar wall as a motor is running? Or is there a thin layer of oil between the rings and the cylindar wall? If the rings do not make contact how close do the rings get? As thin as a human hair or less?
Put some oil on your finger tips and rub them together, that is how close the rings are to the cylinder wall. If a human hair would fit between the rings and cylinder you would have the wrong size pistons installed.
Imagine the rate of oil consumption, if a layer of oil as thick as a hair were left in the combustion chamber every time the piston descends!
It's amazing that healthy engines burn as little oil as they do, with so little wear of rings and cylinders.
It's amazing that healthy engines burn as little oil as they do, with so little wear of rings and cylinders.
Yep, I agree
Originally Posted By: spasm3
Originally Posted By: Donald
Originally Posted By: spasm3
I think they make some contact. But for the most part ride on an oil film. I tend to believe there is less ring to cylinder contact on a bore that has had a 2 step plateau hone as this holds more oil. Moly faced rings had a reputation for holding more oil, i don't know it thats true.
In the 70's-80's most high mileage engines would have a ridge at the top of the cylinder making it difficult to remove the pistons. You don't really see that anymore. Better oil and better cnc machining and honing. Probably better( faster) engine warmup and temperature control as well helps.
Thus the need for a ridge reamer. My Dad had one.
And if you were not careful, you could really screw up a bore using a ridge reamer.
+1 They were amazing how they could peel metal off the wall.
Originally Posted By: Donald
Originally Posted By: spasm3
I think they make some contact. But for the most part ride on an oil film. I tend to believe there is less ring to cylinder contact on a bore that has had a 2 step plateau hone as this holds more oil. Moly faced rings had a reputation for holding more oil, i don't know it thats true.
In the 70's-80's most high mileage engines would have a ridge at the top of the cylinder making it difficult to remove the pistons. You don't really see that anymore. Better oil and better cnc machining and honing. Probably better( faster) engine warmup and temperature control as well helps.
Thus the need for a ridge reamer. My Dad had one.
And if you were not careful, you could really screw up a bore using a ridge reamer.
+1 They were amazing how they could peel metal off the wall.
If they touched a lot you wouldn't see honing marks in the cylinder on a 500,000 mile teardown. There's oil lubricating the rings.
Originally Posted By: spasm3
... In the 70's-80's most high mileage engines would have a ridge at the top of the cylinder making it difficult to remove the pistons. You don't really see that anymore. Better oil and better cnc machining and honing. Probably better( faster) engine warmup and temperature control as well helps.
My Mazda (below) was made in 1980. When I had the head off at 476402 miles, I couldn't find any ridge up there, only some loose carbon.
... In the 70's-80's most high mileage engines would have a ridge at the top of the cylinder making it difficult to remove the pistons. You don't really see that anymore. Better oil and better cnc machining and honing. Probably better( faster) engine warmup and temperature control as well helps.
My Mazda (below) was made in 1980. When I had the head off at 476402 miles, I couldn't find any ridge up there, only some loose carbon.
The reason the ring ridge is gone now days (mostly) is better fuel management. Unburnt gasoline used to wash the cylinder walls down during start-up and warm-up (carbs w chokes). But newer EFI systems keep that from happening which means that the upper ring band still retains its oil film, so wear is reduced. The evidence is that the original hone marks are still visible at 200,000+ miles.
There is about 2~5 molecules thickness of oil on the upper cylinder walls. This is WAY smaller than the finest human hair. The rings are floating on an oil film. The film can remain in place because although it is exposed to hot gasses, the actual oil temp is controlled by the cylinder wall temp which is tied to the cooling system. The cylinder walls are hot, but not over 300*, and usually less... Heavy loads climbing a long grades, yeah, they can get up there. But still within the capability of the oil to do it's job
Ring Lubrication
There is about 2~5 molecules thickness of oil on the upper cylinder walls. This is WAY smaller than the finest human hair. The rings are floating on an oil film. The film can remain in place because although it is exposed to hot gasses, the actual oil temp is controlled by the cylinder wall temp which is tied to the cooling system. The cylinder walls are hot, but not over 300*, and usually less... Heavy loads climbing a long grades, yeah, they can get up there. But still within the capability of the oil to do it's job
Ring Lubrication
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Originally Posted By: spasm3
Originally Posted By: Donald
Originally Posted By: spasm3
I think they make some contact. But for the most part ride on an oil film. I tend to believe there is less ring to cylinder contact on a bore that has had a 2 step plateau hone as this holds more oil. Moly faced rings had a reputation for holding more oil, i don't know it thats true.
In the 70's-80's most high mileage engines would have a ridge at the top of the cylinder making it difficult to remove the pistons. You don't really see that anymore. Better oil and better cnc machining and honing. Probably better( faster) engine warmup and temperature control as well helps.
Thus the need for a ridge reamer. My Dad had one.
And if you were not careful, you could really screw up a bore using a ridge reamer.
True, but if you had a ridge there weren't many options. I remember tearing down and rebuilding a flat head 6 in a Rambler American, the ridge was close to 1/4" in an engine with about 85K miles on it.
Originally Posted By: Donald
Originally Posted By: spasm3
I think they make some contact. But for the most part ride on an oil film. I tend to believe there is less ring to cylinder contact on a bore that has had a 2 step plateau hone as this holds more oil. Moly faced rings had a reputation for holding more oil, i don't know it thats true.
In the 70's-80's most high mileage engines would have a ridge at the top of the cylinder making it difficult to remove the pistons. You don't really see that anymore. Better oil and better cnc machining and honing. Probably better( faster) engine warmup and temperature control as well helps.
Thus the need for a ridge reamer. My Dad had one.
And if you were not careful, you could really screw up a bore using a ridge reamer.
True, but if you had a ridge there weren't many options. I remember tearing down and rebuilding a flat head 6 in a Rambler American, the ridge was close to 1/4" in an engine with about 85K miles on it.
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