lml@lancaironline.net Mailing List Archive

<<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>> << Lancair Builders' Mail List >> <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>> Example (these numbers are approximations, from memory, from recent experience on the test stand): Peak Peak Torsional Combustion Crankshaft Stress BMEP Pressure Theta(p-p) Reversals A) 175 1100 psi 5-8deg ~5 x mean B) 175 850 psi 17-19deg ~3.5 x mean Where "Theta(p-p)" is the rotational angle between TDC and the peak of the combustion pressure event.<< Thanks, George I think you are right on. The problem with communication is often that one jumps in and, trying to save time and words, oversimplifies something and inadvertently obfuscates the point. Some of the "techy" discussions just take more words.. Question, though. In the above table I think you might be overstating the point a little. By your own numbers, the "ideal" angle from TDC to peak pressure is about 13 degrees - the example you picked shows in one case the peak too advance and in the other it is too far retarded. If you took both ROP and LOP conditions and adjusted the spark timing to hold the 13 degrees wouldn't the peak pressure be nearly the same? Or just take the LOP condition (assuming the ROP with standard ignition timing data is the baseline) and adjust the spark to give a 13-degree theta. How would the comparison work out then? What does the fuel consumption look like when the theta is adjust between, say, 0 and 20 degrees ATC? Gary Casey LML website: http://members.olsusa.com/mkaye/maillist.html LML Builders' Bookstore: http://www.buildersbooks.com/lancair Please remember that purchases from the Builders' Bookstore assist with the management of the LML. Please send your photos and drawings to marvkaye@olsusa.com.