lml@lancaironline.net Mailing List Archive

<<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>> << Lancair Builders' Mail List >> <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>> POsted for "Brian Barbata" <barbatab001@hawaii.rr.com>: I was right in there with those defending LOP operation, until I consulted with some of the best rebuilders around last year. I had been running my Bonanza 40 to 80 LOP (GAMIjectors/engine monitor) and recording the numbers for well over a year. I thought I could defend the reasoning and the results to anybody. I had read all the articles. I had talked to GAMI. In 5 minutes with an unbiased, experienced authority on the subject, I was convinced that the risks of an inadvertent detonation far outweigh any possible benefits of LOP. Rebuilders will tell you they can almost always spot an engine that has been run LOP for a significant time. Saving fuel does not justify LOP (maybe you are in the wrong hobby!). Thinking you're saving the engine does not either. You will burn a couple of more gph by running ROP. There is no basis for believing LOP prolongs engine life or avoids catastrophic failures. So, for 5 bucks an hour, you are willing to risk detonation? For a more convincing discussion of this, call John Pava at Victor Aviation ("Black" engines) in Palo Alto at (800) 207-0061. Hard to argue with experience. I'm much more comfortable flying over the ocean 100+ ROP (best power = best speed). BTW, if lower pressures were instrumental in preserving engines, we would all have engines with design cylinder pressures below 40 psi! Someone did a test to determine if pilots were prematurely getting overhauls "to regain power" because of cylinder pressures below 60 (seems to be a magic number). They began filing down the compression rings on a TCM on a dyno, and recording the power output and the pressures under lab conditions. Guess what! There was almost no reduction in power until they got below 40, and even then, it was minimal. They stopped the test because they feared blowing out the sump with the blow-by! Not that we shouldn't pay attention to these numbers, but sometimes they don't produce the effect we logically assume. Brian Barbata LML website: http://www.olsusa.com/Users/Mkaye/maillist.html LML Builders' Bookstore: http://www.buildersbooks.com/lancair Please send your photos and drawings to marvkaye@olsusa.com.