Lancair Legacy - CAFE Foundation

16501600155015001450140013501300Legacy N199L: EGT and CHT spreads at 8,500', 2300 RPMA⊕â⊕⊕⊕⊕A A A A A A⊕V bC⊕= 262 smph @ 12.6 gphâââ11 12 13 14 15 16Fuel flow, gallons per hour (gph)EGT #1EGT #2EGT #3⊕ EGT #5âââA⊕âCHT #1CHT #2CHT #3A⊕âAâA⊕â400390380370360350340330320310300290280270260250240230220210200190180170Legacy N199L; wide open throttle, CAFE data 2/23/02. CHT for 100 °F day.Cont. IO-550-N engine, 310 HP. V bC= speed at best CAFE fuel flow.160CHT #5TASMPG x108.5K/2300: The striking result evident inthis graph is the very flat curve of TAS (trueairspeed in smph) across a wide range ofmixture settings--with very little speedpenalty in running lean mixtures. Becausethe MPG values steadily increase and boththe CHT and EGT steadily decrease as thefuel flow is reduced, it is sensible to fly theLegacy using just 12 gph with wide openthrottle and 2300 RPM and 8,500 feet.Cylinder #3 again shows itself to be thecoolest in CHT and EGT. EGT spreads areabout 50 °F at all fuel flows, somewhat betterthan is typical of fuel injected horizontallyopposed aircraft engines.All of the CHT values, which as shownare corrected for a 100 °F day, are wellbelow the 460 °F redline for CHT. It isinteresting that the CHTs of cylinders #1and #5 are so very similar at all fuel flows,while their EGT values differ markedly.Cylinder #2 is consistently runs hottest atall the power settings tested.The Legacy engine continued to runsmoothly at all of the fuel flow settings presentedhere.That the Legacy can loaf along at just12.0 gph and still deliver 260 smph is veryimpressive. However, its V bC at this RPMand altitude is 262 smph and this occurs at12.6 gph, as shown. The V b C s e t t i n go ffers the best compromise betweenspeed, fuel economy and engine heatstresses. It is a function of many interactingfactors including throttle position, RPM,propeller eff i c i e n c y, altitude and the speedversus drag of the aircraft as a whole.