Cylinder Honing
#22
Here's what he said.
Exactly what I'm going to do!
Hi!
Lining up the rings would not create a problem, they rotate anyway.
Upside down wil sure do it though. I would replace all of the rings, use a very fine emery cloth and oil and roughen the cylinders, I have done that many times.
Then carefully wipe the bores out to remove any residue, wipe down with clean oil and try again.
Ted
Lining up the rings would not create a problem, they rotate anyway.
Upside down wil sure do it though. I would replace all of the rings, use a very fine emery cloth and oil and roughen the cylinders, I have done that many times.
Then carefully wipe the bores out to remove any residue, wipe down with clean oil and try again.
Ted
#23
Dude , with just 30,000 miles all you need to do is put new rings in, but put them in right this time .Just looking at the cylinders should tell you if you really need to take it further and measure.
How about taking a really good picture of the cylinders and posting that.
How about taking a really good picture of the cylinders and posting that.
#24
[QUOTE=Gnarly4X;51320789]
I guess this is where NEARLY ALWAYS comes in..
this is what ted told him..
Hi!
Lining up the rings would not create a problem, they rotate anyway.
Upside down wil sure do it though. I would replace all of the rings, use a very fine emery cloth and oil and roughen the cylinders, I have done that many times.
Then carefully wipe the bores out to remove any residue, wipe down with clean oil and try again.
Ted
I think im with Ted ...
Getting stupid ..no not really just interesting..
I guess this is where NEARLY ALWAYS comes in..
this is what ted told him..
Hi!
Lining up the rings would not create a problem, they rotate anyway.
Upside down wil sure do it though. I would replace all of the rings, use a very fine emery cloth and oil and roughen the cylinders, I have done that many times.
Then carefully wipe the bores out to remove any residue, wipe down with clean oil and try again.
Ted
I think im with Ted ...
Getting stupid ..no not really just interesting..
#26
like i said before... some people need to be told 3-4 times until they get it right... so.. i and gnarly cant' say we didnt tell him so....
Last edited by 1990yota-pickup; Dec 31, 2009 at 06:27 PM.
#28
I suspect Ted's advice is based on the assumption that the boring/honing job 30K ago was done properly, which may very well be the case. However, it would suck to go through all the work of tearing the motor down, then putting it back together to find that upside down rings weren't the only problem.
As for honing, I have no experience. A good friend who graduated from MMI said properly honing cylinders is more difficult than you'd think. Their practice was being carefully checked. Another friend who used to be a diesel mechanic says honing is easy. I'm thinking, yeah, it probably is after you've done a hundred engines, but not for a newbie.
As for honing, I have no experience. A good friend who graduated from MMI said properly honing cylinders is more difficult than you'd think. Their practice was being carefully checked. Another friend who used to be a diesel mechanic says honing is easy. I'm thinking, yeah, it probably is after you've done a hundred engines, but not for a newbie.
Last edited by flyingbrass; Dec 31, 2009 at 06:31 PM.
#29
[QUOTE=Gnarly4X;51320816]
I'd bet that if Ted was rebuilding an engine with 30,000 miles on improperly installed rings, he would MIC the cylinders just to be sure. Ted is certainly one fart smucker when it comes to these engines, BUT he's not the only one that builds engines, and if you ask each Crew Chief of the top 10 NASCAR teams, you'd probably get several different answers!!
With that said, I'd probably take what Ted says seriously, but if it were my engine and my time and my money, I'd mic the cylinders and get one of my good friends who builds engines professionally to give me their opinion before I'd stick a honing tool in it and hone away!!
The original question was about honing cylinders. 90% of this site is laced with F'd up "rebuild" jobs!!
That is just my worthless opinion.
gNARLs.
you are right im sure he would , its probably a bad habit of his . Playing it safe .. yes mic the cylinders , if only to help you sleep better .
I'd bet that if Ted was rebuilding an engine with 30,000 miles on improperly installed rings, he would MIC the cylinders just to be sure. Ted is certainly one fart smucker when it comes to these engines, BUT he's not the only one that builds engines, and if you ask each Crew Chief of the top 10 NASCAR teams, you'd probably get several different answers!!
With that said, I'd probably take what Ted says seriously, but if it were my engine and my time and my money, I'd mic the cylinders and get one of my good friends who builds engines professionally to give me their opinion before I'd stick a honing tool in it and hone away!!
The original question was about honing cylinders. 90% of this site is laced with F'd up "rebuild" jobs!!
That is just my worthless opinion.
gNARLs.
you are right im sure he would , its probably a bad habit of his . Playing it safe .. yes mic the cylinders , if only to help you sleep better .
#30
To the OP how about something to read , remember this is from the INternet..
High Performance Piston Rings and Cylinder Finishes
By Jerry McLain
Today's performance ring sets are thinner, lighter and more conformable than ever before. Thinner, low-tension rings reduce friction for more usable horsepower. Less weight reduces ring groove pound out. Narrower rings also allow tighter tolerances and less blowby. All very good things when you're building a performance engine. But they also require rounder, straighter cylinder bores than ever before.
Though many racers are running 1 mm compression rings, some ring manufacturers are selling compression rings as narrow as 0.6 mm. At the recent Performance Racing Industry show in Orlando, FL, one manufacturer showed us a one-piece 1.5 mm oil ring. The company said the super narrow oil ring is being used in some NASCAR NEXTEL Cup Series engines and is not yet available to the general public. The reason why the rings are being limited to NEXTEL Cup racing is because they are tricky to install and require a zero clearance end gap. These rings are not a true "gapless" design because the ends of the ring just butt up flat against each other.
Another reason for the smaller rings in many performance engines is that pistons are getting shorter. Longer connecting rods with shorter pistons change the combustion dynamics and provide better angularity during the power stroke. Shorter pistons also weigh less, which means the engine can rev higher. But when the piston is shorter, the rings have to move up higher. This means they have to be narrower, stronger and more heat resistant because the top ring is closer to the combustion chamber.
Cast iron piston rings are still a popular choice for dirt track claimer motors as well as many street performance and other racing applications. But cast iron is not in the same league as ductile iron or steel rings when it comes to strength. Ductile iron rings have roughly twice the tensile strength of grey cast iron, and three times the fatigue strength. Steel rings, by comparison, have almost four times the tensile strength and fatigue strength of grey cast iron.
So what does this mean inside an engine? It means ductile iron and steel rings can survive in racing environments that may be too demanding for grey cast iron rings. Stronger rings reduce the risk of ring breakage under severe loads. Steel rings also show less side wear and ring groove pound out.
For high boost turbocharged and supercharged engines, and engines using large doses of nitrous oxide to add horsepower, ductile iron or steel top rings are probably a must. Many racers prefer to use nitrided rings made from steel wire because the rings can handle high loads and thermal shock better than other materials. Nitriding penetrates into the metal and won't flake off like other surface coatings.
Plain uncoated grey cast iron rings are inexpensive and are popular for "budget" motors. But plain cast iron rings should never be used in an engine that burns alcohol because alcohol cuts lubricity. Some type of coated rings must be used with alcohol.
Moly is still the most popular facing material for many piston rings because of its excellent wear and scuff resistance. Another material is tungsten carbide (for hard liners), and chrome. Chrome-faced rings are still a good choice for abrasive environments like dirt tracks, and work best with cast iron blocks and cylinder liners. Chrome rings don't work well with chrome plated bores or hard faced cylinder bore liners such as those coated with nickel/carbide coatings.
Hard Liners
The practice of coating cylinders with nickel and silicone carbide (the best known name is Nikasil, which is a registered trademark of Mahle Gesellschaft) got its start in Formula 1 racing, and is now used in many different levels of racing from circle track to drag racing to motorcycles.
The hard ceramic facing inside the liner is a mixture of nickel and silicon carbide that is only about 0.07 mm (.0025" to .003") thick. Small particles of silicon carbide less than 4 microns in size are dispersed throughout the nickel matrix. The result is a very hard and wear resistant surface that reduces friction and allows the engine to develop more horsepower. The surface has a hardness of about 90 HRc.
The liners are also dimensionally stable and experience less bore distortion than ordinary cylinders, which reduces blowby and leak down (some claim less than 1 percent after extended use). But to seal properly, these liners require two things: moly or tungsten carbide faced rings, and a very smooth bore finish.
The surface of a liner with this coating has microscopic pores that do an excellent job of retaining oil for the rings. Consequently, the bore can be finished to a super smooth finish of 4 to 6 Ra or less to reduce friction even more. Such low numbers would be too smooth for grey cast iron and would likely starve the rings for proper lubrication. Chrome plated bores or liners, by comparison, can also provide good lubrication while reducing friction and wear, but chrome is more vulnerable to dirt scoring and there may be some risk of flaking.
Bore Finish
Regardless of what kind of rings or liners are used in a performance motor, rings usually seat best and last the longest when the cylinder bores are given a plateau finish. A plateau finish essentially duplicates a "broken-in" bore finish, so there is less scrubbing and wear on the rings when the engine is assembled. What's more, if the surface is finished correctly it will provide plenty of flat, smooth bearing surfaces to support the rings while also retaining oil in the crosshatch valleys to lubricate the rings.
The only exception to this is in motors where there is a lot of bore distortion. If the bores go out of round when the head bolts are torqued down, the rings may not seat as well allowing increased blowby and oil consumption. Thinner rings that can conform to the bore will work better in these kinds of applications, but it's also a good idea to use torque plates when honing when honing the bores to simulate the distortion that occurs when the cylinder heads are installed. The other option is to go with a slightly rougher "peaked" finish to seat the rings.
Most ring manufacturers recommend using a two- or three-step honing procedure to achieve a plateau finish. First, rough hone to within .003" of final bore size to leave enough undisturbed metal for finish honing. For plain cast iron or chrome rings in a stock, street performance or dirt track motor, hone with #220 grit silicon carbide stones (or #280 to #400 diamond stones) to within .0005" of final size. Then finish the bores with a few strokes using an abrasive nylon bristle plateau honing tool, cork stones or a flexible abrasive brush.
For moly faced rings in a street performance, drag or circle track motor, hone with a conventional #280 grit silicon carbide vitrified abrasive, then finish by briefly honing to final size with a #400 grit vitrified stone or #600 grit diamond stone (or higher), plateau honing tool, cork stones or a brush.
For stock and street performance engines with moly rings, an average surface finish of 15 to 20 Ra is typically recommended. For higher classes of racing, you can go a little smoother, provided you don't glaze the cylinders.
For moly or nitrided rings in a performance motor, hone with #320 or #400 vitrified stones, and finish with #600 stones, cork stones, a plateau honing tool or brush.
If the cylinders are rough honedwith diamond, they can be finish honed with a finer grit diamond, a fine-grit vitrified abrasive or a plateau honing tool or brush. Because diamond is a harder material and wears more slowly than conventional abrasives, it cuts differently and may require more honing pressure. But many newer diamond stones now use a more friable bond that stays sharp and doesn't load up, allowing the stones to cut smoother and leave a rounder, smoother bore finish.
When using diamond-honing stones instead of vitrified abrasives, you generally have to use a higher number grit to achieve the same Ra (roughness average) surface finish. For example, if you have been using #220 grit conventional stones to finish cylinders for plain cast iron or chrome rings, the equivalent diamond stones might be a #280 to #325 grit. If you have been using #280 grit conventional stones to hone for moly rings, the diamond equivalent might be #400 to #550 grit stones. The actual numbers will vary somewhat depending on the brand and grade of the stones.
Bristle style soft hones (plateau honing tools) have mono-filament strands that are extrude molded with a fine abrasive material embedded in the strands. The filaments are mounted in different types of holders for use with portable or automatic honing equipment. Another type of brush uses molded abrasive balls that are mounted on flexible metal shafts so the balls can easily conform to the surface. Brushing helps sweep away torn and folded metal on the surface while removing many of the sharp peaks to make the surface smoother.
When finishing the cylinders with a brush, only light pressure is required. The rpm of the brush should be similar to that which the cylinder was originally honed, and no more than 16 to 18 strokes should be applied (some say 8 to 10 strokes is about right). Too many strokes with a brush may produce too smooth a finish in a cast iron cylinder that won't retain oil. Reversing the direction of rotation while brushing helps to remove the unwanted material on the surface. The end result should be a cylinder that provides immediate ring seal with little if any wear on the cylinder wall or rings when the engine is first started.
With the right plateau honing techniques, you should be able to get the surface down to an average roughness of 8 to 12 Ra or less, with RPK (relative peak height) numbers in the 5 to 15 range, and RVK (relative valley depth) numbers in the 15 to 30 range. These numbers are meaningless unless you have a surface profilometer that can measure them (which a growing number of performance shops now have).
Crosshatch
Crosshatch is also important because the amount, depth and angle of the crosshatch in the cylinder bores determines how much lubrication the rings receive and the rate of ring rotation.
Excessive shallow crosshatch angles can hinder or slow down the necessary ring rotation that allows the rings to dissipate heat. It can also leave too much oil on the cylinder wall allowing the rings to skate over the surface and the engine to use oil. Too steep of a crosshatch angle may not provide enough oil retention and can result in dry starts and premature ring wear. A steep crosshatch angle can also create excessive ring rotation that accelerates ring and piston groove wear.
Ring manufacturers typically recommend a crosshatch angle of 22° to 32° as measured from horizontal and uniform in both directions.
Bore Geometry
Bore geometry is especially important in performance engines because of the higher cylinder pressures they generate and the higher rpms at which they operate. Torque plate honing is a must with all performance engines to compensate for the bore distortion that occurs when the heads are installed.
Typically, cylinder bores tend to squash in and deform the most in areas that are next to the head bolts. Depending on how many head bolts are around the cylinder (four, five or six), the bore will experience fourth, fifth or sixth orders of distortion. Oblong distortion may also occur from side loading during the honing process.
The cylinders should be round and straight to a tolerance of .0005" (0.13 mm) or less (ideally, .0002" to .0003").
Bore distortions are bad at high rpm because it can prevent the rings from conforming to the surface, allowing more blowby and oil consumption. If the cylinders are not straight, the rings can bounce away from the surface and lose their seal with the same results.
The amount of bore distortion that occurs depends on the block, the location of the cylinders, and the design of the heads and how much loading is on the head bolts. The higher the bolt loads and the less rigid the block, the more distortion that occurs in the bores.
At the PRI show, C-K Engineering Inc. of Baldwin, MO showed a new Cylinder Bore Geometry Gauge that can measure and display bore distortion graphically on a computer. The drawing that results is three-dimensional and color coded to show the areas of greatest distortion. The gauge system is claimed to be accurate down to 1.0 micron (.000040")!
Hot Honing
Hot honing got its start back in the late 1950s and early 1960s when legendary engine builders such as Smokey Yunick and Bill Jenkins experimented with a hot honing process to achieve rounder cylinder bores. The idea was to hone the engine hot (at 200° F) to simulate the bore distortion that occurs when the engine is running. Over the years, various racers have experimented with the process and today a majority of NASCAR engines are hot honed.
Hot honing holds the most promise for endurance engines that run at high rpm for long races (like NASCAR and off-road racing). But it provides less of a benefit for drag racing and street engines. Even so, some Pro Stock drag racers are now hot honing their blocks.
In terms of friction reduction, hot honing is claimed to offer a 1 to 2 percent improvement, which is good for maybe 5- or 6-hp in a 600-hp engine. Tests have shown that some bores can distort as much as .0035" at 220° F compared to room temperature. Less bore distortion when the engine is hot means better sealing and less blowby. The numbers are not huge, but in tightly regulated racing classes every advantage helps.
Several companies now offer equipment that allows cylinder blocks to be honed hot. The equipment typically has a pump and heating unit to circulate hot coolant through the block. The process doesn't totally duplicate a running engine because there is no way (yet) to make the top of the cylinder hotter to simulate the heat effects of combustion. Even so, hot honing will produce rounder, straighter bores in a running engine than honing at room temperature. Just keep in mind that the cylinders will distort when they cool down - but will return to a round condition when the engine fires up and runs.
Ring End Gaps
The old school philosophy of engine building said the end gaps on second compression rings could be tighter because the number two ring is not exposed to as much heat as the top ring. The new school of engine building says it's better to open up the second ring gap 20 to 30 percent so pressure doesn't buildup between the rings and cause the top ring to lose its seal at high rpm. The result is better compression, better piston cooling and reduced oil consumption.
Any pressure that builds up between the rings will blow down into the crankcase, keeping oil out from between the rings. This trick works best on engines that are running a dry oil sump and pull a vacuum in the crankcase.
Some performance pistons also have "accumulator grooves" machined into the piston land between the first and second ring grooves. The added space traps blowby gasses and helps prevent the top ring from unseating and fluttering.
For naturally aspirated engines, a top ring end gap of .004" per inch of bore diameter is often recommended for a stock or moderate performance engine. For a 4-inch bore, that translates into a top ring end gap of .016" to .018". But this will vary depending on the power output of the engine.
For drag or oval track racing, the recommended end gap is somewhat larger (.0045" per inch of bore diameter). With four-inch bores, that would be an end gap of .018" to .020".
For a nitrous oxide street performance engine, the recommended end gap is .005" per inch of bore diameter (.020" to .022" for an engine with four-inch bores). For a nitrous oxide drag engine, the recommended end gap for the top ring is .007" per inch of bore diameter (.028" to .030" with four-inch bores).
With a turbocharged or supercharged racing engine, the top ring gap should be .006" per inch of bore diameter (.024" to .026" with a four-inch bore).
The recommended end gaps for second compression rings are also the same, with slightly larger gaps if you want to minimize pressure buildup between the rings.
The recommended ring end gap for most oil rings (except the new super narrow one-piece rings) regardless of engine application is typically .015".
Another trick to improve ring sealing at high rpm is to run pistons that have gas ports behind the top ring. Combustion pressure blows through the port to help seal the ring from behind and underneath. Some use vertical gas ports with holes drilled from the top of the piston to the top ring groove just behind the ring. Others use lateral gas ports that are drilled through the bottom side of the top land and extend to the back wall of the ring groove. Gas ports work best at high rpm (above 7,000 rpm) and are not recommended for street engines.
Getting rid of the end gap altogether can also improve sealing, cooling and horsepower. Gapless rings eliminate the gap between the ends of the ring by overlapping slightly. Gapless rings are available in popular sizes with various wear-resistant face and side coatings. Some engine builders who have switched to "gapless" top or second compression rings say they've gained three to five percent more horsepower with no other changes. Gapless rings are said to allow less than 1 cubic feet per minute (CFM) of blowby and on alcohol-fueled engines, a gapless top ring or second ring helps keep alcohol out of the crankcase.
High Performance Piston Rings and Cylinder Finishes
By Jerry McLain
Today's performance ring sets are thinner, lighter and more conformable than ever before. Thinner, low-tension rings reduce friction for more usable horsepower. Less weight reduces ring groove pound out. Narrower rings also allow tighter tolerances and less blowby. All very good things when you're building a performance engine. But they also require rounder, straighter cylinder bores than ever before.
Though many racers are running 1 mm compression rings, some ring manufacturers are selling compression rings as narrow as 0.6 mm. At the recent Performance Racing Industry show in Orlando, FL, one manufacturer showed us a one-piece 1.5 mm oil ring. The company said the super narrow oil ring is being used in some NASCAR NEXTEL Cup Series engines and is not yet available to the general public. The reason why the rings are being limited to NEXTEL Cup racing is because they are tricky to install and require a zero clearance end gap. These rings are not a true "gapless" design because the ends of the ring just butt up flat against each other.
Another reason for the smaller rings in many performance engines is that pistons are getting shorter. Longer connecting rods with shorter pistons change the combustion dynamics and provide better angularity during the power stroke. Shorter pistons also weigh less, which means the engine can rev higher. But when the piston is shorter, the rings have to move up higher. This means they have to be narrower, stronger and more heat resistant because the top ring is closer to the combustion chamber.
Cast iron piston rings are still a popular choice for dirt track claimer motors as well as many street performance and other racing applications. But cast iron is not in the same league as ductile iron or steel rings when it comes to strength. Ductile iron rings have roughly twice the tensile strength of grey cast iron, and three times the fatigue strength. Steel rings, by comparison, have almost four times the tensile strength and fatigue strength of grey cast iron.
So what does this mean inside an engine? It means ductile iron and steel rings can survive in racing environments that may be too demanding for grey cast iron rings. Stronger rings reduce the risk of ring breakage under severe loads. Steel rings also show less side wear and ring groove pound out.
For high boost turbocharged and supercharged engines, and engines using large doses of nitrous oxide to add horsepower, ductile iron or steel top rings are probably a must. Many racers prefer to use nitrided rings made from steel wire because the rings can handle high loads and thermal shock better than other materials. Nitriding penetrates into the metal and won't flake off like other surface coatings.
Plain uncoated grey cast iron rings are inexpensive and are popular for "budget" motors. But plain cast iron rings should never be used in an engine that burns alcohol because alcohol cuts lubricity. Some type of coated rings must be used with alcohol.
Moly is still the most popular facing material for many piston rings because of its excellent wear and scuff resistance. Another material is tungsten carbide (for hard liners), and chrome. Chrome-faced rings are still a good choice for abrasive environments like dirt tracks, and work best with cast iron blocks and cylinder liners. Chrome rings don't work well with chrome plated bores or hard faced cylinder bore liners such as those coated with nickel/carbide coatings.
Hard Liners
The practice of coating cylinders with nickel and silicone carbide (the best known name is Nikasil, which is a registered trademark of Mahle Gesellschaft) got its start in Formula 1 racing, and is now used in many different levels of racing from circle track to drag racing to motorcycles.
The hard ceramic facing inside the liner is a mixture of nickel and silicon carbide that is only about 0.07 mm (.0025" to .003") thick. Small particles of silicon carbide less than 4 microns in size are dispersed throughout the nickel matrix. The result is a very hard and wear resistant surface that reduces friction and allows the engine to develop more horsepower. The surface has a hardness of about 90 HRc.
The liners are also dimensionally stable and experience less bore distortion than ordinary cylinders, which reduces blowby and leak down (some claim less than 1 percent after extended use). But to seal properly, these liners require two things: moly or tungsten carbide faced rings, and a very smooth bore finish.
The surface of a liner with this coating has microscopic pores that do an excellent job of retaining oil for the rings. Consequently, the bore can be finished to a super smooth finish of 4 to 6 Ra or less to reduce friction even more. Such low numbers would be too smooth for grey cast iron and would likely starve the rings for proper lubrication. Chrome plated bores or liners, by comparison, can also provide good lubrication while reducing friction and wear, but chrome is more vulnerable to dirt scoring and there may be some risk of flaking.
Bore Finish
Regardless of what kind of rings or liners are used in a performance motor, rings usually seat best and last the longest when the cylinder bores are given a plateau finish. A plateau finish essentially duplicates a "broken-in" bore finish, so there is less scrubbing and wear on the rings when the engine is assembled. What's more, if the surface is finished correctly it will provide plenty of flat, smooth bearing surfaces to support the rings while also retaining oil in the crosshatch valleys to lubricate the rings.
The only exception to this is in motors where there is a lot of bore distortion. If the bores go out of round when the head bolts are torqued down, the rings may not seat as well allowing increased blowby and oil consumption. Thinner rings that can conform to the bore will work better in these kinds of applications, but it's also a good idea to use torque plates when honing when honing the bores to simulate the distortion that occurs when the cylinder heads are installed. The other option is to go with a slightly rougher "peaked" finish to seat the rings.
Most ring manufacturers recommend using a two- or three-step honing procedure to achieve a plateau finish. First, rough hone to within .003" of final bore size to leave enough undisturbed metal for finish honing. For plain cast iron or chrome rings in a stock, street performance or dirt track motor, hone with #220 grit silicon carbide stones (or #280 to #400 diamond stones) to within .0005" of final size. Then finish the bores with a few strokes using an abrasive nylon bristle plateau honing tool, cork stones or a flexible abrasive brush.
For moly faced rings in a street performance, drag or circle track motor, hone with a conventional #280 grit silicon carbide vitrified abrasive, then finish by briefly honing to final size with a #400 grit vitrified stone or #600 grit diamond stone (or higher), plateau honing tool, cork stones or a brush.
For stock and street performance engines with moly rings, an average surface finish of 15 to 20 Ra is typically recommended. For higher classes of racing, you can go a little smoother, provided you don't glaze the cylinders.
For moly or nitrided rings in a performance motor, hone with #320 or #400 vitrified stones, and finish with #600 stones, cork stones, a plateau honing tool or brush.
If the cylinders are rough honedwith diamond, they can be finish honed with a finer grit diamond, a fine-grit vitrified abrasive or a plateau honing tool or brush. Because diamond is a harder material and wears more slowly than conventional abrasives, it cuts differently and may require more honing pressure. But many newer diamond stones now use a more friable bond that stays sharp and doesn't load up, allowing the stones to cut smoother and leave a rounder, smoother bore finish.
When using diamond-honing stones instead of vitrified abrasives, you generally have to use a higher number grit to achieve the same Ra (roughness average) surface finish. For example, if you have been using #220 grit conventional stones to finish cylinders for plain cast iron or chrome rings, the equivalent diamond stones might be a #280 to #325 grit. If you have been using #280 grit conventional stones to hone for moly rings, the diamond equivalent might be #400 to #550 grit stones. The actual numbers will vary somewhat depending on the brand and grade of the stones.
Bristle style soft hones (plateau honing tools) have mono-filament strands that are extrude molded with a fine abrasive material embedded in the strands. The filaments are mounted in different types of holders for use with portable or automatic honing equipment. Another type of brush uses molded abrasive balls that are mounted on flexible metal shafts so the balls can easily conform to the surface. Brushing helps sweep away torn and folded metal on the surface while removing many of the sharp peaks to make the surface smoother.
When finishing the cylinders with a brush, only light pressure is required. The rpm of the brush should be similar to that which the cylinder was originally honed, and no more than 16 to 18 strokes should be applied (some say 8 to 10 strokes is about right). Too many strokes with a brush may produce too smooth a finish in a cast iron cylinder that won't retain oil. Reversing the direction of rotation while brushing helps to remove the unwanted material on the surface. The end result should be a cylinder that provides immediate ring seal with little if any wear on the cylinder wall or rings when the engine is first started.
With the right plateau honing techniques, you should be able to get the surface down to an average roughness of 8 to 12 Ra or less, with RPK (relative peak height) numbers in the 5 to 15 range, and RVK (relative valley depth) numbers in the 15 to 30 range. These numbers are meaningless unless you have a surface profilometer that can measure them (which a growing number of performance shops now have).
Crosshatch
Crosshatch is also important because the amount, depth and angle of the crosshatch in the cylinder bores determines how much lubrication the rings receive and the rate of ring rotation.
Excessive shallow crosshatch angles can hinder or slow down the necessary ring rotation that allows the rings to dissipate heat. It can also leave too much oil on the cylinder wall allowing the rings to skate over the surface and the engine to use oil. Too steep of a crosshatch angle may not provide enough oil retention and can result in dry starts and premature ring wear. A steep crosshatch angle can also create excessive ring rotation that accelerates ring and piston groove wear.
Ring manufacturers typically recommend a crosshatch angle of 22° to 32° as measured from horizontal and uniform in both directions.
Bore Geometry
Bore geometry is especially important in performance engines because of the higher cylinder pressures they generate and the higher rpms at which they operate. Torque plate honing is a must with all performance engines to compensate for the bore distortion that occurs when the heads are installed.
Typically, cylinder bores tend to squash in and deform the most in areas that are next to the head bolts. Depending on how many head bolts are around the cylinder (four, five or six), the bore will experience fourth, fifth or sixth orders of distortion. Oblong distortion may also occur from side loading during the honing process.
The cylinders should be round and straight to a tolerance of .0005" (0.13 mm) or less (ideally, .0002" to .0003").
Bore distortions are bad at high rpm because it can prevent the rings from conforming to the surface, allowing more blowby and oil consumption. If the cylinders are not straight, the rings can bounce away from the surface and lose their seal with the same results.
The amount of bore distortion that occurs depends on the block, the location of the cylinders, and the design of the heads and how much loading is on the head bolts. The higher the bolt loads and the less rigid the block, the more distortion that occurs in the bores.
At the PRI show, C-K Engineering Inc. of Baldwin, MO showed a new Cylinder Bore Geometry Gauge that can measure and display bore distortion graphically on a computer. The drawing that results is three-dimensional and color coded to show the areas of greatest distortion. The gauge system is claimed to be accurate down to 1.0 micron (.000040")!
Hot Honing
Hot honing got its start back in the late 1950s and early 1960s when legendary engine builders such as Smokey Yunick and Bill Jenkins experimented with a hot honing process to achieve rounder cylinder bores. The idea was to hone the engine hot (at 200° F) to simulate the bore distortion that occurs when the engine is running. Over the years, various racers have experimented with the process and today a majority of NASCAR engines are hot honed.
Hot honing holds the most promise for endurance engines that run at high rpm for long races (like NASCAR and off-road racing). But it provides less of a benefit for drag racing and street engines. Even so, some Pro Stock drag racers are now hot honing their blocks.
In terms of friction reduction, hot honing is claimed to offer a 1 to 2 percent improvement, which is good for maybe 5- or 6-hp in a 600-hp engine. Tests have shown that some bores can distort as much as .0035" at 220° F compared to room temperature. Less bore distortion when the engine is hot means better sealing and less blowby. The numbers are not huge, but in tightly regulated racing classes every advantage helps.
Several companies now offer equipment that allows cylinder blocks to be honed hot. The equipment typically has a pump and heating unit to circulate hot coolant through the block. The process doesn't totally duplicate a running engine because there is no way (yet) to make the top of the cylinder hotter to simulate the heat effects of combustion. Even so, hot honing will produce rounder, straighter bores in a running engine than honing at room temperature. Just keep in mind that the cylinders will distort when they cool down - but will return to a round condition when the engine fires up and runs.
Ring End Gaps
The old school philosophy of engine building said the end gaps on second compression rings could be tighter because the number two ring is not exposed to as much heat as the top ring. The new school of engine building says it's better to open up the second ring gap 20 to 30 percent so pressure doesn't buildup between the rings and cause the top ring to lose its seal at high rpm. The result is better compression, better piston cooling and reduced oil consumption.
Any pressure that builds up between the rings will blow down into the crankcase, keeping oil out from between the rings. This trick works best on engines that are running a dry oil sump and pull a vacuum in the crankcase.
Some performance pistons also have "accumulator grooves" machined into the piston land between the first and second ring grooves. The added space traps blowby gasses and helps prevent the top ring from unseating and fluttering.
For naturally aspirated engines, a top ring end gap of .004" per inch of bore diameter is often recommended for a stock or moderate performance engine. For a 4-inch bore, that translates into a top ring end gap of .016" to .018". But this will vary depending on the power output of the engine.
For drag or oval track racing, the recommended end gap is somewhat larger (.0045" per inch of bore diameter). With four-inch bores, that would be an end gap of .018" to .020".
For a nitrous oxide street performance engine, the recommended end gap is .005" per inch of bore diameter (.020" to .022" for an engine with four-inch bores). For a nitrous oxide drag engine, the recommended end gap for the top ring is .007" per inch of bore diameter (.028" to .030" with four-inch bores).
With a turbocharged or supercharged racing engine, the top ring gap should be .006" per inch of bore diameter (.024" to .026" with a four-inch bore).
The recommended end gaps for second compression rings are also the same, with slightly larger gaps if you want to minimize pressure buildup between the rings.
The recommended ring end gap for most oil rings (except the new super narrow one-piece rings) regardless of engine application is typically .015".
Another trick to improve ring sealing at high rpm is to run pistons that have gas ports behind the top ring. Combustion pressure blows through the port to help seal the ring from behind and underneath. Some use vertical gas ports with holes drilled from the top of the piston to the top ring groove just behind the ring. Others use lateral gas ports that are drilled through the bottom side of the top land and extend to the back wall of the ring groove. Gas ports work best at high rpm (above 7,000 rpm) and are not recommended for street engines.
Getting rid of the end gap altogether can also improve sealing, cooling and horsepower. Gapless rings eliminate the gap between the ends of the ring by overlapping slightly. Gapless rings are available in popular sizes with various wear-resistant face and side coatings. Some engine builders who have switched to "gapless" top or second compression rings say they've gained three to five percent more horsepower with no other changes. Gapless rings are said to allow less than 1 cubic feet per minute (CFM) of blowby and on alcohol-fueled engines, a gapless top ring or second ring helps keep alcohol out of the crankcase.
#32
My point .. just giving him something to read remember his original question.
silly willy of course hes not building a race engine, but who better to learn from .. and of all the people reading this thread I thought you might like it ..you were the first one to bring up Nascar engine builders.
so Like I said just giving the guy something to read.
silly willy of course hes not building a race engine, but who better to learn from .. and of all the people reading this thread I thought you might like it ..you were the first one to bring up Nascar engine builders.
so Like I said just giving the guy something to read.
#33
Yes, I'm going to check all of the cylinders out before I install the new rings.
This is not a racecar, so tolerances aren't severe.
What happens when you install piston rings upside down??? I have even compression in all the cylinders...so we can throw out the idea of poor compression. I don't know if I put them on upside down or not. I know for a fact that the oil rings were installed in line with eachother.
This is not a racecar, so tolerances aren't severe.
What happens when you install piston rings upside down??? I have even compression in all the cylinders...so we can throw out the idea of poor compression. I don't know if I put them on upside down or not. I know for a fact that the oil rings were installed in line with eachother.
#34
I think everyone needs to take some pills and calm down.
I don't know why everyone is getting so upset...
Anyway, I never stated I was not going to measure the cylinders/bore to make sure they were in spec. But that still doesn't mean the machinist did his job either.
I don't know why everyone is getting so upset...
Anyway, I never stated I was not going to measure the cylinders/bore to make sure they were in spec. But that still doesn't mean the machinist did his job either.
#35
91...
If you want to do it right, you should contact the ring manufacturer and asked them what they recommend for their rings. Honing is THE most critical machining process to successfully getting the rings to seat properly. The cross-hatch angle and the Ra (surface roughness) is very important. After that, it's the break in procedure. Synthetic oil during break in is not recommended, and the rings should seat by 2K or 3k miles.
Or you can just wing it.
gNARLS.
If you want to do it right, you should contact the ring manufacturer and asked them what they recommend for their rings. Honing is THE most critical machining process to successfully getting the rings to seat properly. The cross-hatch angle and the Ra (surface roughness) is very important. After that, it's the break in procedure. Synthetic oil during break in is not recommended, and the rings should seat by 2K or 3k miles.
Or you can just wing it.
gNARLS.
My brother used synthetic oil to break his 22r in. If I ask you you will say its bad, but if I asked Amsoil they will say the opposite...so who do I trust?
Get my point?
#37
What happens when you install piston rings upside down??? I have even compression in all the cylinders...so we can throw out the idea of poor compression. I don't know if I put them on upside down or not. I know for a fact that the oil rings were installed in line with eachother.
The second compression ring is supposed to have a taper on one side. If upside down, I can see how that could cause a problem. What about the top ring? How is it directional?
Writing on the rings should face up toward the top.
Another thing to be mindful of when installing is the middle (big) oil ring. Its edges should butt together, not overlap.
#38
Good question. Maybe you should ask Ted?
The second compression ring is supposed to have a taper on one side. If upside down, I can see how that could cause a problem. What about the top ring? How is it directional?
Writing on the rings should face up toward the top.
Another thing to be mindful of when installing is the middle (big) oil ring. Its edges should butt together, not overlap.
The second compression ring is supposed to have a taper on one side. If upside down, I can see how that could cause a problem. What about the top ring? How is it directional?
Writing on the rings should face up toward the top.
Another thing to be mindful of when installing is the middle (big) oil ring. Its edges should butt together, not overlap.
The second ring certainly does have a taper. Maybe I got lucky and they are installed correctly?
#39
Everyone needs to settle down. Everyone has their own opinion. Everyone has made mistakes. Everyone is supposed to be here to help each other.
Building an engine is building an engine. Using strict, minimal tolerence variations is the best way to do it and is known as "blueprinting". Using ball-type honing stones is perfectly acceptible and preferential for someone who has never done it before since they are the least likely to damage the cylinder walls. They're also perfectly fine if the bores measure near the tight spec for taper and roundness, at which point all you need is a crosshatch to seat the rings.
If you're serious about throwing it, toss it my way. 
.030 over isn't the end of the world- you can take the block to .060 if you have to. Mic'ing the bores would tell you how much, if any work is needed.
Get the pistons out and have the cylinders checked for taper and round. You can do it yourself if you don't mind buying telescopes and calipers capable of measuring the cylinder diameter. You check them measuring front to rear then left to right at a minimum of three places in the bore- top, middle and bottom. If the front/rear is the same as the left/right measurement, the hole is pretty round. As you go down the bore, if that remains true for each level, the cylinder out-of-round is minimal. If the different levels read the same, or within .001 or so, there is no taper.
Rings installed upside down will work fine but won't last as long as they should since, in particular, the bevel on the fire rings will be pointing up and as such, carbon build up from the minute amount of oil that gets in the ring land won't help push the ring out to the cylinder. You might get away with simply flipping the rings but the heat it's experienced will affect its temper and reduce it's "springy-ness" and that could cause it to take a lot longer to seat if it's re-used.
As for the clocked oil-rings, if they all were lined up, they'll let oil by more easily but won't significantly affect compression.
Sounds to me like you need to pull it, check the cylinders... THEN decide which way to go.
Building an engine is building an engine. Using strict, minimal tolerence variations is the best way to do it and is known as "blueprinting". Using ball-type honing stones is perfectly acceptible and preferential for someone who has never done it before since they are the least likely to damage the cylinder walls. They're also perfectly fine if the bores measure near the tight spec for taper and roundness, at which point all you need is a crosshatch to seat the rings.
So why don't I just take my engine out and throw it in the trash can?
Its already .030 over. Now I have to buy another set of pistons, rebuild a whole other engine just because the oil rings were put on wrong and possibly the other rings too.
Your telling me my 30k mile engine is worthless....and throughout 30k miles the bore's are off and it needs to be bored again???
Its already .030 over. Now I have to buy another set of pistons, rebuild a whole other engine just because the oil rings were put on wrong and possibly the other rings too.
Your telling me my 30k mile engine is worthless....and throughout 30k miles the bore's are off and it needs to be bored again???

.030 over isn't the end of the world- you can take the block to .060 if you have to. Mic'ing the bores would tell you how much, if any work is needed.
Get the pistons out and have the cylinders checked for taper and round. You can do it yourself if you don't mind buying telescopes and calipers capable of measuring the cylinder diameter. You check them measuring front to rear then left to right at a minimum of three places in the bore- top, middle and bottom. If the front/rear is the same as the left/right measurement, the hole is pretty round. As you go down the bore, if that remains true for each level, the cylinder out-of-round is minimal. If the different levels read the same, or within .001 or so, there is no taper.
Rings installed upside down will work fine but won't last as long as they should since, in particular, the bevel on the fire rings will be pointing up and as such, carbon build up from the minute amount of oil that gets in the ring land won't help push the ring out to the cylinder. You might get away with simply flipping the rings but the heat it's experienced will affect its temper and reduce it's "springy-ness" and that could cause it to take a lot longer to seat if it's re-used.
As for the clocked oil-rings, if they all were lined up, they'll let oil by more easily but won't significantly affect compression.
Sounds to me like you need to pull it, check the cylinders... THEN decide which way to go.
Last edited by abecedarian; Dec 31, 2009 at 09:25 PM.



, an engine can nearly ALWAYS be rehoned and reringed/repistoned at least ONCE before needing to be rebored.