Colin Rainy wrote: > IMHO for it to be scientific, the test should have been performed with (5) > 2700cc cranks nitrided examined, and (5) 2700cc cranks w/o nitriding > examined for similar use engines and those results compared. The 3100cc > engine is a throw away invalid, because rods and psitons are different > which contaminate the accuracy of the information. >>From the (4) 2700cc engines, 50% cracked and 50% did not. Why? What was >>the same about them, and what was different? > How were they used differently or the same? What was the fuel type used, > base timing settings, carbs, props, compression ratio? How were the 2 > engines used > that did not crack vs. the 2 that did suffer cracks?
Having read the comments of engine experts (aircraft, heavy equipment, etc) in the field who's first question was "are you sure that crank was nitrided" (see http://home.hiwaay.net/~langford/corvair/flexplate/problem.html ) is all I need to know. It's considered standard practice in industries in which maximum crankshaft longevity is expected. It's guaranteed insurance of significantly more fatigue resistance for the crank. The reason William didn't use 5 cranks of either type is because he doesn't HAVE 5 nitrided cranks to check, and it would be irresponsible to sit around waiting for them. But seeing 7-8 cracked or broken cranks (most of them in KRs) in the last year is enough for any logical thinker to conclude that there is a problem that needs fixing, and a $50 nitride job is a pretty good step in the right direction. If he kept quiet on this issue it would just be a matter of time before he had a broken crank that didn't just result in a forced landing and a trashed engine, but would involve totalled airplanes and/or deceased friends... Mark Langford, Huntsville, Alabama see KR2S project N56ML at http://home.hiwaay.net/~langford email to N56ML "at" hiwaay.net
