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Cylinder Sleeves – Not Sexy, but Necessary

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Sleeve installation continues to be a solid market for engine builders and machine shops

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Sleeving – at its crudest definition – is fixing a round hole. However, you better believe there is much more than that going on, and the opportunity for engine builders and machine shops to make money is tremendous. Whether a block is vintage or brand new, sleeves can play a major role in keeping an engine viable and performing well.

As aluminum continues to be a preferred material for newer engine blocks, and as the existing cast iron blocks continue to be driven for more and more miles and under tougher and tougher operating conditions, sleeves and cylinder liners will continue to be the saving grace – keeping these engines running and allowing engine builders to push the limits of performance.

This is a Honda B18 closed deck block with LA Sleeves installed.
Photo courtesy of LA Sleeve.

Why are sleeves used?

Cylinder sleeves, often made of either gray cast iron or ductile iron, are used to restore the cylinder to a usable size. When the original cylinder bore is too badly worn or damaged, a cylinder sleeve can be an option for salvaging the block, or a sleeve can strengthen a block to handle more power than originally intended by the factory.

A Toyota 3S GTE Amphibian Procross Procool sleeved block. Photo courtesy of LA Sleeve.

“The main reason is to get a stronger, more durable, more wear-resistant cylinder bore,” says Brent Boyle, machine shop and centrifugal manager at Powerbore / Quaker City Castings. “Especially in today’s market, aluminum blocks are becoming more and more popular and we know that aluminum and heat and aluminum and friction are not really compatible.”

As a block surface, metallurgy experts say, aluminum is great for everything that you would need except for the bore surface, and that’s where you see a lot of sleeves and liners.

A Mitsubishi EVO block with Darton MID sleeves installed. Photo courtesy of Darton Sleeves.

“Newer engines lack cylinder strength or structure,” says Howard Anderson, owner of AR Fabrication, an engine shop and Darton sleeve installation facility. “A lot of engines have aluminum blocks with a coating, and they’re great for the stock OEM cylinder pressures, but 99 percent of our business is dealing with somebody who would like to create more power. So a sleeve is introduced into the cylinder and it allows for higher cylinder pressures. We can hone for many different types of rings and types of performance once we do that. It opens up a lot of options for our clientele.”

While sleeves can make aluminum blocks even better, they can also restore older, cast iron blocks back to their glory days.

Engine work and sleeve installation from AR Fabrication comes with a 1-year warranty. Photo courtesy of AR Fabrication.

“The older engines, in almost every case, are being sleeved in a restoration situation where a block has either been bored to its max, so it’s got to be brought down to size, or perhaps because of a failure that was so catastrophic that it would need a sleeve inserted to reinforce the weakened walls,” says Dave Metchkoff, GM and VP at LA Sleeve.

This is an example of a sleeve being machined. Photo courtesy of Darton Sleeves.

Keys to installation

On the surface, there is seemingly nothing too difficult about installing cylinder sleeves, however, the process takes a good machinist, good measuring and the proper knowledge to install sleeves that don’t cause engine problems shortly after installation.

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“We do a few iron block sleeve installations, but most of our businesses is aluminum,” Anderson says. “The difference is the clearances required for the sleeve. There’s also clearance differences between using a dry liner versus the Darton MID sleeve. We’re talking .0005˝ to .001˝, but it’ll make or break the installation and whether it’s going to fail prematurely or not. The clearances need to be correct for each individual sleeve.”

Honing requirements change as well, and if  your shop doesn’t have newer technology and equipment, you’re going to have a tough time getting things straight.

“The sleeves that we utilize have several grades,” Anderson says. “If we use a higher-grade material and you tried to use a vitrified stone machine to hone it, most likely you’re going to make garbage out of the cylinder and it’s going to be out of round and taper and very difficult to keep straight. But with diamonds and CBN technology (and a lot of work on our part to get it right) we can keep the cylinders within a tenth or two and not have any issues.”

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Just as new technology can play a big part in being precise, so too can the material of the sleeves being used.

“Shops compare our ductile iron with machining/installing cast iron sleeves,” says John Catapang of Darton Sleeves. “Yes, they are both iron, but our material far exceeds the hardness of normal gray cast iron. You cannot bore out as much material at one time as you would with cast iron or aluminum blocks. Speeds and feeds need to be adjusted when using ductile iron. You cannot install a sleeve that exceeds 100,000 tensile strength the way you would a sleeve that is only 30,000 tensile.”

This Mitsubishi 4B11 block is being honed for sleeve installation. Aluminum blocks like these benefit from sleeves for higher horsepower capability. Photo courtesy of AR Fabrication.

What this all boils down to is the importance of being accurate. According to Boyle, making sure your diameters are true and your ledges are perpendicular is crucial to being accurate.

“If everything is square and everything is round and you’re accurate on fitting your sleeve to your block, all that’s left is making sure that you’re precise on your hone finish according to the piston rings you’re using and everything should work out fine,” Boyle says.

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Melling’s Dan McDonell, GM of the cylinder sleeve plant in Maquoketa, IA, echoes Boyle’s advice. “Engine builders have to make sure that when installing cylinder sleeves they press them in square – don’t beat them in. Press them in and make sure they’re seated on the bottom ledge and they should have no problems,” he says.

Since accuracy is key when sleeving, many engines require the use of a stress plate to accurately measure the diameter and roundness of the cylinder. Measuring the cylinders of these engines without the stress plate can give false readings.

“A stress plate assures the cylinder will be the correct size once the engine is reassembled,” says Steve Scott, director of product development at Industrial Parts Depot, LLC (IPD). “If these style blocks are machined in a free state (without a stress plate) the cylinder may distort once the cylinder head is torqued in place.”

With so much riding on properly installed sleeves, it’s no surprise that some engine builders and machine shops get nervous or skittish working on sleeved engines if they’ve had failures before, or don’t have much experience. The biggest concern for these folks is having the sleeves stay in place.

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“The most prevalent and most talked about issue on a sleeve motor are sleeves dropping or sinking,” Metchkoff says. “When a sleeve sinks .001˝-.004˝, the gaskets have a harder time sealing because it doesn’t have a stable, flat surface for a head gasket to press down and compress against. The first and foremost issue is the way sleeves are installed. When you’re putting in either a straight wall sleeve or flange top sleeve, the most common problem is the bottom of the flange or the bottom of the sleeve bouncing off the bottom of the register.”

The old school version of sleeving those is to either freeze the sleeve or heat the block, which reduces resistance for the sleeve to be placed in the block. The sleeve has either a step or a register and the installer will ultimately take a mallet or a hammer and hit the top of the sleeve to force it all the way down.

“An inexperienced installer won’t get a feel for what’s happening, but the sleeve will bottom out and the installer will hammer the top of the sleeve one last time, and when they do that, the sleeve bounces off that register and will actually move up .001˝-.002˝ and they won’t know it,” Metchkoff says. “Over time with heat, the sleeve will slowly sink down, finding the bottom of that register again.”

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The same thing occurs on a flange top installation in which you cut a counterbore on the deck of the block. The flange sleeve will go down and if it’s not pressed down all the way against the bottom of the register or it’s forced down too hard against the bottom of the register, the sleeve will pop itself back up.

“Everything will come with experience,” Anderson says. “When you’re in your first couple hundred sleeve jobs, you’re really not going to find that you’re making a wrong decision on an installation until a year or two later. You can make an adjustment to what you’ve done, but experience and the more you do you’re going to realize the nuances of getting it right.”

If you’re able to install sleeves and can keep 99.9 percent of your cylinder pressure above the piston rings, you’re going to generate more power. When you have 3-7 percent blow-by past your rings, you’re not running at full potential.

“There’s always going to be a battle between longevity and performance,” Boyle says. “Longevity says I can take a sleeve and chrome coat it or nickel chrome coat it and that sleeve is going to last forever, but it’s not going to perform to its max potential. To do that, go away from the coatings, go to a nice, true bore finish that the rings will agree with and everything seals up and all your compression stays above the rings, and that’s where your max potential is going to come from. Unfortunately, it’s not going to last as long as a coated liner will, but if you’re running on the edge every weekend looking for max performance, there’s no coating out there that’s going to give you that.”

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Diesel vs. Gas

When looking at sleeves for either a diesel or gas engine, the materials are not necessarily too different. However, there are some things that are important to note if doing sleeve installations on diesel applications versus gas.

“Many of today’s higher horsepower industrial engines use steel pistons or steel piston crowns and aluminum piston skirts,” Scott says. “These types of pistons allow for much tighter clearances as opposed to aluminum pistons that require more clearance due to thermal expansion. Less clearance between the piston and cylinder wall make the diameter and roundness of the liner even more critical than before.”

Most of the larger industrial engine blocks are cast iron, but later-style blocks are much lighter and more prone to twisting. Likewise, the liners for these engines have mostly been cast iron, but we are now seeing the use of steel liners.

“Some of the big earth-mover motors, for instance, use a hardened material on the upper half of the sleeve and what they do in that situation is they flame harden their material because the cylinder pressures are so tremendous on a big diesel like a Series 60 Detroit or a big Cummins,” Metchkoff says. “That does require some harder material just to contain that violent compression, but for the most part, the liners are going to be the same material for either dry blocks or wet.”

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The vast majority of industrial diesel blocks made after 1970 had replacement liners in them. They did that because the manufacturer wanted it to be a serviceable block and the only way you can service them in the field is to have a liner that can be removed by pulling the heads off, swapping pistons, putting new liners back in, reassembling and putting on new gaskets. However, light-duty diesel blocks, like a 6.4L Power Stroke or Durmax, are all cast iron blocks.

“Those have been a huge problem,” Metchkoff says. “Motors that have over 250,000 miles tend to fracture and microfracture – we’ve see it in the 6.4L Power Stroke, 6.6L Duramax and 6.0L Ford. Those same motors are being used for weekend truck pulling now.

“Guys will bolt on different turbos and they’ll truck pull. Those blocks are also fracturing at very frequent rates, and I’m talking motors that have 10,000 miles on them. Those things are fracturing now because they’re simply being pushed beyond their capabilities for what they were designed for. That light-duty diesel market has been really big for us.”

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The diesel side of sleeving will require different piston rings and different bore finishes as well.

“I know that most of the diesel side likes the bore finishes to be fairly rough,” Boyle says, “and that’s with a standard ductile iron ring or coated ductile iron ring, but for a tool steel ring they do like to see them get a little bit smoother. You definitely want to have the deep grooves in diesel for oil retention, but with the tool steel rings, you’re going to want to see that more plateaued finish so it’s flattened off.”

Sleeves Aren’t Rolling

Up Anytime Soon

As Darton’s John Catapang points out, you are limited when it comes to making something that only comes in a circle, but what you make that circle out of is what makes the difference. When it comes to the market for sleeving among engine builders and machine shops, the opportunities are plenty.

“As long as OEM manufacturers keep making aluminum blocks, the desire for people to go fast and make more power than needed will always be an opportunity for engine builders,” Catapang says. “We will keep changing metallurgy to keep up with power level changes and we’ll continue to change designs to fit those OEM blocks.”

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Powerbore’s Brent Boyle agrees that the market for sleeving offers enormous opportunities to engine builders looking to get involved.

“I think the opportunity is definitely going to increase, especially in the high performance market,” Boyle says. “High performance in itself  – really, any sport that involves an engine – is just not going to stop until they just can’t go anymore.

“That’s the evolution of the sport – to always get on top of your competitor and that’s why it never stops, and it won’t stop until either restrictions hold them back or the limitations that they’re dealt won’t allow them to go anymore,” Boyle predicts.

These limits can be seen today when it comes to some 3,000 horsepower diesel engines having problems with blocks splitting. They’re blowing in half, they’re cracking in half, blowing heads off, etc.

“There’s not yet a material out there that they can make a block out of without sleeves that’s actually a high strength, great material for a block,” Boyle says. “I mean you’re getting into the steel grades, which are heavy. Steel doesn’t have the microstructure form of a good, self lubricating, oil-absorbing material. Ductile does, but it’s still the same property as steel where you’ve got vibration properties in it. The last thing you want in an engine block is material that carries vibration properties to it. They havent found a very good material that’ll handle a high horsepower application for a block –  that’s where the sleeves come into play.”

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According to the experts, altthough gray cast iron and ductile iron sleeves will remain  the most commonly used materials for the distant future, because they’re so effective, some sleeve manufacturers have experimented with aluminum liners, steel liners, compacted graphite iron and even titanium liners.

“You need plating on aluminum to have some surface finish – or rings won’t live on it – and the same for steel,” Metchkoff says. “Steel is a very hard material and very strong, but too abrasive for piston rings and it’s just hard to get ring seal on them. Titanium is a really cool option, but we need probably 20 years to figure out how to make it a viable option for our customers.”

In the meantime, the market has remained steady and the shops offering sleeving services have been busier than ever.

“The market is always going to be,” Metchkoff says. “It’s never going to go away –  that much we know because it’s such a fabric of automotive engines, period.”

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The market and service is entrenched. As long as there are failures that sleeves can remedy, people will be installing them.

“Probably the biggest challenge is convincing shops that are in business and can machine to get into sleeving,” he says. “There are fewer and fewer young people who care about getting into this type of market, and so the machine shops that are in business, and know what they are doing, are busier than ever.” ν

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