By now some of you are probably wondering what cryogenics is, and what it has to do with British cars? If you're planning to perform an engine rebuild, or upgrade in the near future, this just might be of interest. Read on, and at least you'll know as much as I do.

Cryogenics (or cryonics) is the process of treating various types materials to a deep freeze for a predetermined amount of time, and has been proven to help enhance their structural properties. In many cases it provides greater strength, better wear characteristics, and/or provides more stable dimensional tolerances. Studies have shown that knives stay sharper longer, mower blades last longer, gun barrels show increased accuracy with improved life, golf balls travel further and last up to three times longer, and even tennis racket strings last up to three times longer with less vibration transferred to the handle. For the women reading this article, pantyhose have been found to last up to 6 months longer! Maybe this means no more running back into the house to change after catching your leg on those jagged British car door edges! Most importantly for all British car owners, engine parts subjected to wear have been proven to last up to five times longer, with improved performance.

Cryogenically treating steel parts to a deep freeze is not an alternative to the heat treating process of steel parts, but instead finishes what heat treating fails to accomplish. The process starts off by slowly exposing the steel to a very cold temperature, and reducing the temperature at approximately .5 to 1 degree per minute, then allowing it to soak for an extended period of time. This completes the transformation of austenites to martensites. This transformation starts during the traditional heat treatment of steel alloys, but not entirely, thus the need for the deep freeze. The more carbon in the material, the colder and longer the parts are required to be kept at a low temperature. After a "cold soak" of minus 300 degrees Fahrenheit (sometimes as cold as minus 459 degrees Fahrenheit (absolute zero - thanks Colleen!), the parts are returned to room temperature at a slow rate of maybe .5 to 1 degree per minute. The entire cryogenic process, from start to finish, can take up to 72 hours to complete.

Christopher Wilkins writes that cryogenic treatment of materials dates back to the late 1930's when Soviet investigators discovered that treatment of cutting tools immersed in liquid nitrogen increased their capabilities in certain instances. In 1942, the Massachusetts Institute of Technology found that a certain favorable combination of properties could be found only by including a cold treatment in the processing cycle of a tool steel. I've been told that in days gone by, a certain German auto maker used to set their engine blocks outdoors during the very cold winter months to artificially age them before assembly, in an attempt to accomplish what today's technology can do colder and faster.

Here's a very basic explanation of what happens while cryogenically treating steel. Austensite is a softer grain structure that is always present after heat treating. It is transformed into a harder and more durable grain structure called martensite. The percentage of retained austenite after heat treating may be as high as 50%, or as low as 3%. The amount retained depends partly on the heat treating operator and the accuracy of the heat treating equipment. Cryogenic treatment simply continues the conversion initiated by the heat treatment by further completing the process by converting almost 100% of the retained austenite to the more desirable martensite. As the percentage of martensite is increased, wear resistance is increased, and the material obtains a more uniform hardness throughout.

The fine ETA carbide particles, called precipitates, are formed during the long cryogenic soak. These are in addition to the larger carbide particles that are present before the start of the cryogenic treatment. It is these fine particles, called fillers, that along with the larger particles, form a denser more coherent and importantly tougher matrix in the material. Since the surface energy of the martensite is higher than that of the austenite, due to the differences in their atomic structures, you then have a potential wear situation. The martensite is less likely to tear out from the parent material than is the austenite. Cryogenic treatment conclusively reduces the wear on materials.

Cryogenic processing is now being used by NASCAR and other racing teams. They have taken advantage of this treatment to reduce wear of their engine components and increase horsepower which are important to their crossing the finish line. Some of the engine components treated include blocks, push rods, valves, camshafts, brake rotors, crankshafts, heads, and even spark plugs and spark plug wires. I'm not quite sure I'd go so far as to having my spark plugs or ignition wires treated, but the next time I do an engine rebuild, I just might look into having some of the other parts chilled.

So, the next time you decide to call your local machine shop to have your head reworked, or camshaft reground, ask them about cryogenics. They just might say CRYO-WHAT?

Below is a list of items that can be cryogenically treated, along with some of the benefits