It ma
lot of it owners fret most about which cylinders to buy. And we’ll they should, given the number of recalls, ADs, service bulletins and warranty squabbles. Common questions we hear are these: Which cylinder should I buy? Should I go with new or overhauled? Chrome, steel or nickel carbide for the barrel?
In the January 2007 issue, we addressed the issue of overhauls exhaustively, concluding that in a world of competitively priced new cylinders, overhauls still retain a toehold. Related to that is cylinder bore treatment.
In days of yore, the standard advice was that if you flew a lot, you bought steel barrels and if you flew a little, you bought channel chrome as downside protection against corrosion from underuse. Channel chrome is still available but due to environmental concerns, far fewer shops are providing it and, increasingly, many field shops have turned to nickel carbide treatments instead.
Nickel carbide has definite advantages over chrome, not the least of which is more reliable break-in. Chrome cylinders were and are notorious for glazing during break-in, causing high oil consumption that wont abate until the cylinder glaze is honed away. Nickel carbide, in contrast, appears to wear better than either chrome or steel. For about $90 to $150 a cylinder, its a modest fraction of the cost of an overhaul, even for a four-cylinder engine.
But should you consider it? Or just take your chances with steel? Here are the pros and cons.
Background
While the automotive industry marches smartly forward with advanced engine technology, little of that progress trickles directly to light aircraft engines. Nickel carbide cylinder plating is a rare exception. Nickel carbide plating was developed by the German firm Mahle in 1967 as a means of reducing rotor-to-housing wear in rotary engines.
Marketed under the trade name Nikasil, it first appeared in piston-engine production cars from Porsche in 1973. By the 1990s, BMW, Honda and other carmakers were using Nikasil treatment, which wore we’ll enough to allow elimination of cast iron liners in aluminum blocks, a big production plus.
Nickel carbide plating is done via conventional electrolytic plating that yields a dense, hard deposition and a surface thats relatively ductile, has excellent hardness and corrosion resistance. It also lubricates we’ll because the surface matrix is oleophilic, providing points where oil can collect.
As with any new processes, however, Nikasil wasnt wart free. It proved unpredictably vulnerable to fuel with high sulfur content, which breaks up the plating and causes catastrophic loss of compression. This wasnt an issue in Europe, but came to light only in the U.S. and other countries where high-sulfur fuel is common.
For aviation markets, beginning in 1994, ECI adapted Mahles and others base work to plate steel cylinder barrels and trademarked the process as CermiNil. It was ECIs second foray into cylinder plating, following the demise of another process called CermiCrome, which the company also pioneered. CermiCrome impregnated ceramic material into the bore surface to improve wear and break-in performance, but owners experienced premature bore wear, which ECIs Ed Salmeron says was traced to hardness specs in piston rings that had been changed without ECIs knowledge. The harder rings simply wore away the plated surfaces faster than had been anticipated. As these problems surfaced in the early 1990s, CermiNil was under development and the company decided to drop CermiCrome.
Some 15 years and 100,000 cylinders into the program, ECI has evolved the process to what it calls Nickle+Carbide, which is applied as an option to new cylinders in its Titan line. The trade name CermiNil is still used but ECI applies it only to its overhauled cylinder line, as we reported in the January issue. Both processes are identical, however.
In the Titan line, Nickle+Carbide carries a $121 per cylinder optional premium over plain steel. In the overhauled Freedom line, the upsell price is $88. For the Titans, ECI offers a five-year warranty on the barrel surface, although not on the entire cylinder itself.
Although ECI pioneered nickel carbide in the aviation market, its no longer alone in the field. In 2000, Aircraft Cylinders of America in Tulsa, Oklahoma, began offering its own version of nickel carbide called Nikarama. Its custom work on most popular cylinders except small displacement O-200 and O-300 variants. The price is $159 per cylinder, with typical turnaround of 14 days. There’s no specific warranty but the shop says it will stand behind the work and make right any problems.
Field Reports
To gain a sense of nickel carbide performance in the field, we surveyed about two dozen owners through our online news service, www.avweb.com. We also talked to