The Big Squeeze: Wiseco Forged Ring Compressors!

February 19, 2020 / by Paul Huizenga

The right tools make the difference between a simple task and a painful ordeal. Wiseco’s piston ring compressor sleeves are an indispensable addition to any engine builder’s toolbox, and make it easy to do the job right the first time.

Before the Internet, even before mail order titans like Summit and Jegs, there was a certain catalog printed in black and white on newsprint, with hand-drawn illustrations and the full-retro feel of something straight out of the 1950’s transported to the ultra-modern eighties. Seat covers! Opera lights! Tachometers! Replacement composition gaskets for everything from a slant-six to a Model T!

Some of those mail order products were more practical than others...

And let’s not forget the infamous “re-ring kit.” Is your MG burning oil faster than it can leak it? Let your ink-stained fingers do the walking through the catalog and pick out a set of replacement rings, a cylinder hone, and of course the dreaded Universal Ring Compressor Tool. This adjustable monstrosity made it possible (if just barely) to stuff those stock pistons back into the bores, once you’d cleaned them up with some steel wool and a pocket knife and managed to get the new ‘high performance’ rings (made from an alloy that defied metallurgical science by being simultaneously soft AND brittle) into their grooves without snapping them in half.

Modern low-tension ring packages require less force to install than old-school rings, but they need a more careful approach.

A Better Way

Today, for anything more performance-oriented than a lawn tractor, a rebuild will require a few specialized tools, and that rusty adjustable ring compressor your dad used to stuff slugs back in their bores should stay in the water-stained cardboard box it’s in now. To do the job right, you’ll need the appropriate ring compressor sleeve sized for your engine’s bore, like the ones offered by Wiseco Pistons. “With 5/64-inch rings, the effort to install the pistons was so high that a dead blow hammer was imperative,” Wiseco’s Vic Ellinger explains. “Today’s rings can be installed with the pressure of your thumbs. Honestly, any more pressure than that and I am looking to be sure something isn’t wrong.”

Ring technology has come a long way in the past half-century, and the techniques involved in engine building have changed along with it. Instead of relying on high static tension to provide a compression seal and proper oil control, today’s ring packages are optimized for low friction and dynamic sealing properties that keep cylinder pressure and lubrication where they belong without adding drag and wear. But they also require a more nuanced touch when putting it all together.

Bore-size-specific ring compressors are a necessity for any engine builder's toolkit.

You Can Never Be Too Rich Or Too Thin?

“With today’s ultra-thin rings and proprietary plating and coatings, the install phase of the build is extremely important to not damage or break the ring,” says Ellinger. A bore-specific one-piece ring compressor sleeve is an essential tool for this critical assembly step, and Wiseco’s compressors are precision-engineered in the same way their pistons are, using some of the same manufacturing equipment. Per Ellinger, “Wiseco forges the ring, then machines it to size with a predetermined amount of taper in the sleeve to gently compress the rings as the skirt enters the bore. We hard-anodize the sleeve to prevent wear over time. They are also laser marked with our Wiseco logo and size to easily identify each one in your tool box.”

Wiseco offers ring compressors in both metric and inch sizing for almost every popular bore diameter.

Does a ring compressor sleeve really need to be forged instead of cast? Probably not, but Wiseco uses the same processes to manufacture them that they do to create their forged high performance pistons, holding them to the same tight tolerances and quality control standards. The compressors also get some of the same surface treatments available for Wiseco pistons, in order to make them more wear-resistant and easier to use.

Ellinger explains, “Anodizing and Teflon coatings prevent wear and/or damage to the sleeve, rings, and pistons during the install phase. The coatings on the rings and pistons need to go in the cylinders undisturbed - this is especially critical if your parts have a break-in coating or lube on them.” On that topic, he adds, “Be mindful of the amount of oil used on the parts to assemble them. ‘Dipped in oil’ isn’t a good thing. Quality oil like Joe Gibbs break-in oil should be used on the skirts, and ideally a light break-in oil or powder applied to the rings from Total Seal should be used. In a pinch, WD-40 can be sprayed on the rings to prevent micro-welding on start-up. Also remember that the wrist pin will want to be lubed with an assembly lube, too.”

The forged aluminum ring compressors have a precise taper to help keep the rings square to the bore during insertion, and a hard-anodized surface with a Teflon finish eases installation without removing break-in lube applied to the rings.

The Path To Success

Besides having the right tool for piston installation, Ellinger has some other tips for DIY engine builders. “The biggest thing to do when you get your block at the machine shop is to inspect the top of each cylinder with your machinist to make sure you and him are comfortable with the chamfer of the block,” he advises. “If there is little to no chamfer on the top of the bore, it will be nearly impossible to install the rings. Before you get home is the time to double-check that the shop did not miss dressing the top of the bore after boring and honing. They have specialized cone-shaped stones to put a chamfer on the bore that won’t slip and ruin a fresh block.”

Once you get your newborn block home, a little bit of patience and attention will go a long way to avoid problems as you install your fresh slugs. Ellinger adds, “The number one error is not getting a feel for what is happening as the piston is installed in the bore. Try to identify each ring making its way past the chamfer at the top of the bore and into its home in the cylinder. Even with the sleeve, you can have a ring pop out between the sleeve and deck surface if you don’t hold the sleeve square on the deck once you are pushing the piston down in its bore.”

Having the right ring compressor is vital for proper piston installation in any high-performance engine build.

A Lid For Every Pot

Wiseco offers high-performance pistons for everything from powersports to domestic V8 engines, so it should come as no surprise that they also produce the tools necessary to do the job right for just about any engine build, with ring compressors in practically any diameter you could want. “In metric sizes, we are nearly covered in .5mm increments from 65mm-104mm,” Ellinger says. “On the V8 ranges, currently we go from 2.579-4.6250 inches. We are always adding bore sizes as the need arises, but for the most part we have almost every popular engine size available today.”

New Sizes numbers Now Available!



Ring Compressor Sleeve - 72.5mm


Ring Compressor Sleeve - 78.5mm


Ring Compressor Sleeve - 3.9220


Ring Compressor Sleeve - 4.0900


Ring Compressor Sleeve - 4.0950


Ring Compressor Sleeve - 4.1000


Ring Compressor Sleeve - 4.2500


Ring Compressor Sleeve - 4.2800


Ring Compressor Sleeve - 4.3100


Ring Compressor Sleeve - 4.3200


Ring Compressor Sleeve - 4.3500


Ring Compressor Sleeve - 4.3750


Ring Compressor Sleeve - 4.4400


Ring Compressor Sleeve - 4.5000


Ring Compressor Sleeve - 4.5300


Ring Compressor Sleeve - 4.5600


Ring Compressor Sleeve - 4.6000


Ring Compressor Sleeve - 4.6100


Ring Compressor Sleeve - 4.6250


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Written by Paul Huizenga