Why is fuel consumption higher at low RPM?

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Discussion Overview

The discussion revolves around the fuel consumption of engines at low RPM compared to higher RPM levels. Participants explore why fuel consumption appears to be higher at lower RPMs, referencing specific RPM values and questioning the validity of data presented in an image.

Discussion Character

  • Debate/contested
  • Technical explanation

Main Points Raised

  • Some participants assert that fuel consumption is higher at 900 RPM than at 1600 RPM, questioning the accuracy of the data presented.
  • Others challenge the initial claims about fuel consumption rates, suggesting that the data may have been misinterpreted.
  • One participant proposes that longer heat loss to cylinder walls at lower RPMs could reduce energy conversion efficiency.
  • Another participant questions whether heat loss occurs even when the engine is at working temperature.
  • Several participants reference an external thread for additional context and information related to the topic.

Areas of Agreement / Disagreement

Participants express conflicting views on the relationship between RPM and fuel consumption, with no consensus reached regarding the accuracy of the data or the underlying reasons for the observed fuel consumption patterns.

Contextual Notes

There are unresolved questions about the assumptions underlying the analysis of fuel consumption at different RPMs, particularly concerning heat loss and energy conversion efficiency.

Who May Find This Useful

Individuals interested in engine performance, thermodynamics, and fuel efficiency may find the discussion relevant.

mandala09
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Why are usually more wasteful fuel engine at low RPM, as the example image below, 900 RPM more wasteful fuel consumption than 1600 RPM.
 

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Last edited:
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mandala09 said:
Why are usually more wasteful fuel engine at low RPM, as the example image below, 1600 RPM more wasteful fuel consumption than 900 RPM.

Mr Mandala, if I may be corrected, the data shown in the picture upside down with your statement. fuel consumption at 900 rpm is higher than at 1600 rpm. why is that? What kind of analysis?
 
wahyudi.jr said:
Mr Mandala, if I may be corrected, the data shown in the picture upside down with your statement. fuel consumption at 900 rpm is higher than at 1600 rpm. why is that? What kind of analysis?

Excuse me sir, I was wrong to write and I have to change it. Can you help me to analyze it?
 
Part of the issue will be the longer time that heat can be lost to the cylinder walls, reducing the amount of energy to expand the air and be converted to mechanical energy.
 
mender said:
Part of the issue will be the longer time that heat can be lost to the cylinder walls, reducing the amount of energy to expand the air and be converted to mechanical energy.

Although the engine was already in the working temperature if the heat will still be lost in the cylinder wall ?
 

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