lml@lancaironline.net Mailing List Archive

<<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>> << Lancair Builders' Mail List >> <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>> Jeff, Disclaimer: I don't own a IV, I'm building my 360, and hope not to have those issues by running a Diesel/Jet Fuel engine. I have to admit that I've been converted by John Deakin (www.avweb.com), as far my cessna flying is concerned. His argument is so thorough technically, that it leaves little doubt: "The only type of engine that shouldn't be run lean of peak is when fuel distribution across cylinders is not even enough." - That's my bottom line interpretation of his articles. Running your engine lean of peak results in a cleaner exaust, because you're using excess air, not excess fuel to limit combustion temps. This means that all the fuel is getting burned unlike what happens when you run rich of peak. The issue is when you don't have good fuel distribution you get one of two conditions: 1 - Some cylinders are lean of peak, some cylinders are rich of peak - Not good 2 - Some cylinders are nicely lean of peak, some cylinders are so lean there's no combustion - Even worse - That's what the roughness is all about But with the GAMIjectors, you should get such an even fuel distribution you can lean your engine right down to the point you don't get any combustion at all. No roughness because all cylinders quite burning at the same time. Well that's the sole technical reason they're suposed to be so great. If you have individual cylinder engine monitoring package, you can confirm that by watching how even your EGT's and CHT's will be as you lean. If you don't have such engine monitoring package, use a power setting lower than 65% and see how far can you lean. If you can get 100 degrees lean of peak, smoothly add power until you get the indicated airspeed you'd get at 75% power settings. Remember that when using power settings under 65%, any mixture won't hurt the engine by definition. The bottom line is if you can get the power up while keeping the mixture that low, you ARE alright. It's great for the engine to run drastically lean of peak. It's not that great to run it just a little lean of peak. Once you can get a 75% LOP setting, add MP while reducing mixture as much as possible. The farther you can get the better for the engine. The only potential negative factor is the turbos will be working harder, which long term reduces their useful life. But it looks like you're saving a lot more on fuel that on a shorter turbo life. John Deakin's articles (http://www.avweb.com/toc/columns.html). All that's said here is just interpretation of what he said. Marcelo Pacheco PP-ASEL IFR 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.