Control System Development

Control System Development

Welcome to the BLTE Discussion site... Daniel Woody

Engine Performance Criteria

Problems with the MPG Comparison Method:

The Criteria for engine comparison as suggested and derived from the automotive industry is measured in “Miles per Gallon” (MPG) which would be (loosely considered) vehicle fuel efficiency versus “Gallons per Mile” ( GPM ) which would be (loosely considered) vehicle fuel consumption.  With an initial inspection this method of engine comparison has little to do with engine performance except how an engine may be performing in a land vehicle.  This method of analysis is subject to many external influences which makes this measurement technique almost useless.  Even in two identical vehicles or the same vehicle driven by different operators at different times can produce wildly different results. 

 

Some problems inherent with this technique are:

  • Fuel consumption results are dependent on the road conditions (especially curves, hills, stops, smoothness, wet pavement where water is pumped away from the tire contact to the roadway)
  • Driver differences as with rates of acceleration, accelerations and decelerations while attempting a constant speed, idle time, friction braking frequency, turns and lane changing
  • Precipitation where every drop of rain or snow get accelerated to the vehicle speed
  • Barometric pressure where the engine has more power with increasing pressure and less power with reduced pressure
  • Fuel consumption is dependent on which way the wind is blowing

In every instance the criteria and the basis of MPG comparison are vehicle based, poorly measured and subjectively compared. 

In addition different types of vehicles equipped with the same engine will produce different results.  For instance a pick-up truck versus an excavator would also produce wildly different results.

 

Other problems inherent with this technique are:

  • Aircraft fuel consumption does not translate without creative math to “Miles per Gallon”
  • Marine fuel consumption does not translate without creative math to “Miles per Gallon”
  • Rail fuel consumption does not translate without creative math to “Miles per Gallon”
  • Generator fuel consumption has no relationship to this measurement criteria
  • Other technologies such as external combustion, solar powered and fuel cell conversions are not even considered because they cannot be applied to this measurement method

The alternative offering is to use true engine characteristics represented by a 3-dimentional (3D) graph to make power plant comparisons.  These 3D characteristics are “ RPM ” (Revolutions per Minute or revs) on the X-Axis, “Efficiency”  on the Y-Axis and Power or Torque (where Power=Torque • RPM ) on the Z-Axis.

 

 

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