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naturalextraction · 07-18-2013, 05:48 PM

Part of the efficiency of and engine is it'a ability to move air with fuel of course as the accelerant. The engine is not much more than an air pump with a lot of parasitic losses. Taking advantage of the volume in the chamber with more air and fuel to combust is volumetric efficiency. Changing the cam profile to move less air to de-tune or changing the cam profile, does not make it more efficient and then to just bring in more air, is still less efficient. The I.V.E. on the side of my bike stands for "Increased Volumetric Efficiency" just to state the obvious technically.

So you detune and bring up volumetric efficiency now from a lower starting point. Also the cam grinds provide max efficiency at different load and rpm ranges usually for a specific or intended use. I wont even begin to get into the many factors and variables that change efficiency regarding extraction of the internal chemical energy to provide the chemical leverage/energy in these SICE engines. They are by design not very efficient to begin with. The numbers seem to change depending on the source for typical four valve high swirl port combustion chambers, efi, engines. Some were from 35 to 38% with diesels approaching 45%. With DPI systems, variable cam timing, ignition systems and timing etc, efficiencies creep up some. There are many good books out there regarding a massive amount of research related to Spark Ignition Compression Engines and what brings up their "efficiencies" which also have multiple definitions related to certain aspects of it's operations and intended uses.

Here is one of my favorites related to your question in many areas of the book and is well written The Romance of Engines [R-188]: Takashi Suzuki: 9781560919117: Amazon.com: Books

This book by Dr. John Heywood from MIT and the Sloan School of Automotive Engineering, will very specifically in much technical detail answer every bit of your questions. I suggest looking for a used version or renting it on line as it's a bit pricey. Internal Combustion Engine Fundamentals: John Heywood: 9780070286375: Amazon.com: Books

Pretty much any question you can come up with there is an answer and there are reasons related to the intended use and build that most, especially motorcycle engines, already maintain a pretty high efficiency for it's intended use. Understand why high compression in itself increases efficiencies. Good basic thinking thought process though.

07-18-2013, 05:48 PM	#16 (permalink)
naturalextraction naturalextraction Join Date: Mar 2009 Location: New Mexico Posts: 116 Thanks: 3 Thanked 39 Times in 30 Posts	Part of the efficiency of and engine is it'a ability to move air with fuel of course as the accelerant. The engine is not much more than an air pump with a lot of parasitic losses. Taking advantage of the volume in the chamber with more air and fuel to combust is volumetric efficiency. Changing the cam profile to move less air to de-tune or changing the cam profile, does not make it more efficient and then to just bring in more air, is still less efficient. The I.V.E. on the side of my bike stands for "Increased Volumetric Efficiency" just to state the obvious technically. So you detune and bring up volumetric efficiency now from a lower starting point. Also the cam grinds provide max efficiency at different load and rpm ranges usually for a specific or intended use. I wont even begin to get into the many factors and variables that change efficiency regarding extraction of the internal chemical energy to provide the chemical leverage/energy in these SICE engines. They are by design not very efficient to begin with. The numbers seem to change depending on the source for typical four valve high swirl port combustion chambers, efi, engines. Some were from 35 to 38% with diesels approaching 45%. With DPI systems, variable cam timing, ignition systems and timing etc, efficiencies creep up some. There are many good books out there regarding a massive amount of research related to Spark Ignition Compression Engines and what brings up their "efficiencies" which also have multiple definitions related to certain aspects of it's operations and intended uses. Here is one of my favorites related to your question in many areas of the book and is well written The Romance of Engines [R-188]: Takashi Suzuki: 9781560919117: Amazon.com: Books This book by Dr. John Heywood from MIT and the Sloan School of Automotive Engineering, will very specifically in much technical detail answer every bit of your questions. I suggest looking for a used version or renting it on line as it's a bit pricey. Internal Combustion Engine Fundamentals: John Heywood: 9780070286375: Amazon.com: Books Pretty much any question you can come up with there is an answer and there are reasons related to the intended use and build that most, especially motorcycle engines, already maintain a pretty high efficiency for it's intended use. Understand why high compression in itself increases efficiencies. Good basic thinking thought process though. Last edited by naturalextraction; 07-19-2013 at 12:47 AM..