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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> extropy-chat-bounces@lists.extropy.org [mailto:extropy-chat-bounces@lists.extropy.org] <b>On Behalf Of </b>Max More<br><b>Sent:</b> Sunday, April 10, 2011 10:42 AM<br><b>To:</b> ExI chat list<br><b>Subject:</b> Re: [ExI] Fuel efficient car for anywhere but America<o:p></o:p></span></p><p class=MsoNormal><o:p> </o:p></p><div><p class=MsoNormal>On the negative side of diesel, not only is it more expensive -- at least in the USA; I don't recall the difference the last times I was in Europe -- but it seems that cars and trucks running on diesel are MUCH noiser. Is this a necessary feature of diesel. (I find that unlikely.) If not, why does it seem to be typical? I see and hear small pick-up trucks that sound like enormous commercial trucks ("lorries" for the UK). Can someone point me to a *brief* but informative answer?<span style='color:#1F497D'> Max</span><o:p></o:p></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Sure can. Diesel engines have a higher compression ratio (they need to) in order to ignite the fuel/air mixture. At the end of the power stroke, when the exhaust valve opens, the pressure inside the cylinder is higher in a Diesel than in an equivalent gasoline engine. So with identical sound muffling equipment, the Diesel will be inherently louder, because of the pressure differential between the exhaust valve and the manifold. <o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>All is not lost. If we use a small Diesel and a constant speed and constant load as in a series hybrid, we can design an exhaust system that will hold the noise level within reason. Diesel engines are great if they are used under ideal speed and load.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>spike<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p></div><div><p class=MsoNormal> <o:p></o:p></p></div><p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p></div></body></html>