Cold parts,Hot  Performance

The Mystery of Cryogenic Engine Treatments

By Doug Kaufman
Senior Executive Editor
Dkaufman@babcox.com

There's an old axiom in racing: "To finish first, you must first finish." To achieve that goal, racers desperately have turned to engine builders who promise increased horsepower from all types of miracle porting methods, custom fuel mixes and other mysterious processes. Now, many successful racers are turnin to cryogenic engine treatments for longer lasting, better performing parts.

According to racers, engine builders and treatment providers, cryogenci engine treatments may be the most exciting yet least understood performance enhance avaliable today. It's important to know not only what cryogenics is, but also waht it is not, lest you think the process is just a bunch of hot air.

Cryogenics is smiliar to heat treating in that the metal is strength ened, but it is not made harder by the process, just more durable. Cryogenic processing involves lowering the temperature of metal engine components to more than -300°F. This cooling process "apparently" rearranges the crystals within the metal, realigning the atomic structure and relieving stress,

say apparently, because while we think we know most of how cryogenics works, we're not completely certain," he explains. Most of what we do know is based on theories, and so far it has worked out well.

When a piece of steel or cast iron is hardened, it is heated up into a range Where the atoms of iron and the atoms of carbon form a particular type of crystal called austenite. This has a relatively soft grain structure. The cryogenic process causes this austenite to change to the more wearresistant, yet more brittle martensite, which presents a more even crystalline structure. The parts are then tmpered again to strengthen the metal. Without going into an advanced metallurgical dissertation, casting, cutting, welding, grinding and boring - actually all machining processes -introduce stress into metal.

Basically, how cryogenic treatment works is this: engine blocks, pistons, crankshafts or any other component is placed into a cryogenic treatment chamber. The chamber is sealed, and the temperature is then slowly lowered to -320°F using liquid nitrogen. The subfreezing condition is maintained for serveral hours; then the temperature is carefully and slowly raised again. Many materials then require a heat tempering cycle, so the temperature is raised even higher and then returned to ambient. These cycles may be repeated as needed.

Precise control of these processes is critical, and the computerized chambers must remain sealed during the cycles. To properly treat components may take from several hours to many days, after which the treated parts are stronger and more structurally stable.  As points out, the the theory about how it works is one thing; the fact that the U.S. Army has tested cryogencis for its helicopter's rotor gears and seems to be impressed by the process says even more.

But what does the concept mean in the real world? It's not an entirely new process, but it certainly isn't a universally accepted procedure. According to new computerized technology has only recently

made it a reliable process.

"It's been around for decades, but in the past, the only way people had to treat something using cryogenics was to dunk the parts in liquid nitrogen," explains "That's like putting an ice cube in a cup of hot water. Besides melting, it will crack because of thermal shock."

says that even though they recognized that cryogenics could be a valuable tool, users could not avoid the microfractures on the metal's surface.

"Propagation of these cracks would lead to failure of the piece and, voila, 'cryogenics doesn't work.'"

A self-described industry training resource, says today's treatment methods, which use liquid nitrogen flashed to vapor and computer-controlled dispersal systems, use no liquid in the treatment chamber, so parts are treated gently adn completely.

Is there any opportunity for you to benefit from cryogenic treating processes?

"We have people running cryo-treated parts in everything: radio-controlled engines, go karts, snowmobiles, jet skis, ATVs, motorcycles, small and big block V8s, NHRA Pro Stock, aluminum funny cars and top fuel dragsters, cast iron diesel engines for tractor pulling, even aircraft applications," points out. Bob Reed, 300 Below, Decatur, IL. "Yeah, there's opportunity."

Facilities such as Reed's,facilities nationally that treat various engine components. "Primarily, we treat for the end user, including professional race teams," says Reed, "but we work with engine builders, as well."

Wayne Dill, Dill Performance, Mt. Airy, GA, is one engine builder who relies on cryo treatments for service to his customers. "Any amount of rebuilding I do, I cryo treat my rings, so the end gap doesn't grow as fast. I also cryo the rods- as well as any other parts where I'm seeing a high incidence of wear. Dill points out that the go-kart racing classes for which he builds hundreds of motors a year are incredibly stressful on the engines."We're turning engines at twice their intended limit. The valvetrain stability is not too good at that level, so we need to do what we can to strengthen them."

While nearly all engine parts are candidates for cryogenic treatment, how they respond under stressful racing conditions will vary. Typically, though ,piston rings will seal better against treated cylinder walls, reducing blow-by and increasing horepower. Blocks will not distort from overheating and vibration. Valve springs will last longer. Cranks and camshafts will be more resistant to cotact fatigue. "Typically, we can double or triple the life of the parts," explains

However, says claims that cryogenically treated parts are indestructible or that a treated engine will not blow are just nonsense. "We have the connecting rod pieces to prove it," he says. "The rod had a casting flaw in it,"

and the engine was putting out more than four times the horsepower it was designed to. The inevitable happened, but the engine had already run more than three times as long as its non-cryogenically treated twin."

According to experts, more than 75% of engine components fail because of fatigue. To the engine builder and racer alike, the benefits of this lengthy treatment process are three-fold: increased dimensional stability, stress relief and improved wear resistance.

The durability is obvious, but cryogenics can also provide a hidden benefit - more power. explains:

"Less wear will mean reduced friction. Reduced friction means higher torque and horsepower. It will be a subtle difference, but overall you're looking for wear resistance, so extra horsepower is a plus."

agrees. "We don't market our procedure as an increase in horsepower - there are too many variables that go into it. But , we do consistently build horsepower in repeatable situations. A Pro Stock drag race engine was processed through our system, and the team gained seven horsepower. That may not sound like much, but to the degree this class pushes the performance limits, they'll send tens of thousands of dollars to clip on -tenth of a second off their times."

Motorsports is a particularly good application for cryogenic treatments, because teams get the dual benefits of improved performance, plus they're lessening the component failure reates. But other applications also offer similar opportunites to sell the process.

"In addition to the hardcore racers, it's appropriate to offer the service to people with the '57 Corvette, the ;53 Jagurar or the 1940 Maserati, " says Reed. "When the numbers on your vintage car are all correct, you don't just get on the phone and order a replacement head - the replacement parts just aren't out there anymore."

Lengthening the lifespan of vintage parts may help keep the classic car hobby alive, but even the best cryogenic process can not put new life back into worn out parts. A classic car expert's  best chance for success is to do the necessary machine work to restore the part to its best condition and then have it treated.

Cryogenic treatment is not a coating, nor is it a simple surface finish that can simply be "machined out." The computerized treatment process ensures that the thickest cross-section of the metal is treated - in other words, the entire volumn of the metal is structually changed throughtout. As such, a certain amount of  machining can be done after the parts are treated.

"Because is stabilizes the metal to a greet degree, we have

many racers who will give us their piston slugs to be treated, and then they'll machine the pistons later," says "It's the same with engine blocks. We recommend they do the gross machining, then the cryogenic treatment and then the finish machining. They'll get a very stable block."

In additon to a potential money making process, cryogenic treatment is an even more effective money saving procedure, one that every machine shop can benefit from.

According to a 1998 article in Modern Application News magazine, the  largest market for cryogenic treatment is cutting tools. For the engine rebuilder, this can mean drills, taps, dies, inserts, as welll as deburring tools for working on cylinder heads and it's all very good news.

"Shops can reduce their consumable tooling budget by half by having their tooling last longer," says Reed. "Cryogenic treatment will allow tools to keep sharp edges longer, which means they run longer before they have to be sharpened. Obviously, this is more efficient, meaning less downtime."

Engine builder Dill says he's learned the hard way what cryogenics can mean. "All of my half-inch sockets and all of the 7/16ths tools get tremendously beat down. The cast iron I get has so much sand in it that it just breaks my boring bar bits down, so we cryo them as well. The procedure doubles life of my tooling."

lists a number of  the leading "cryo myths," one of which is, "We can't afford to put any more money into our tooling or product, even to make it better." In response, explains that research has shown that the original cost of the tool is only about 10% of the total cost of using the tool. The greatest costs of using a tool are tooling failure. "And tooling failures create downtime, scrap, lost production, mneetings, delays, product failures, fingerpointing and on and on."

Says Britt Ponder, Ponder Racing Service, Cumming, GA, "especially for the shops who are selling cryogencially treated parts, treating the tooling is important as well. I'd feel sorry for the machining guys who ruin their tools on our cryoed parts!"

Other opportunities

Ponder offers another interesting approach to what makes an appropriate market for cryogenics. "This is more than just marketing hype. We put things through a lot of stress so we know it works. I would think that shops that do a lot of fleet work - big trucks, cars, whatever - for companies trying to get a lot of life out of the parts would find this an amazing benefit. Companies have vehicles on the road that face mechanical diffculties. This could solve a lot of that."

Although NHRA Pro Stock and Top Fuel drag racing teams, as well as Winston Cup NASCAR crews have paid attention to cyrogenics, Purvis points out that the teams who have to pay their own way during the racing season may benefit most from the procedure.

"Sportsman drag racers, for instance, would see a huge benefit from this," Purvis explains. "They would save a lot of money not having to buy parts so offen."

Says Ponder, "Cryogenics is not very expensive, considering the prize moneny that's at stake today. If you're putting a engine together and can make it last -even doubling the life - you and your customer will be way ahead."

The advantages are definite, though sometimes hard to quantify, says Dill. "It's not one of those things where you'll be able to say it's a tenth of a second faster here or there. It's just 'enhanced' It gives us the ability to build a higher quality, longer lasting motor."

That, builders and treaters agree, is the cold, hard fact. AR