Fuels and Engine efficiency Mechanical Engineering

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Discussion Overview

The discussion revolves around the fuel efficiency of two vehicles, a supercharged spark ignition car and a turbocharged diesel engine car. Participants are tasked with calculating the average fuel energy consumed per kilometer based on provided specifications and equations. The scope includes mathematical reasoning and homework-related inquiries.

Discussion Character

  • Homework-related, Mathematical reasoning

Main Points Raised

  • One participant presents a homework problem involving two cars, detailing their specifications and asking for calculations regarding fuel efficiency.
  • The participant provides equations for converting fuel consumption metrics and attempts to calculate energy consumption for Car A.
  • Another participant questions the necessity of converting from SI units to British/American units.
  • There are repeated inquiries about the correctness of the calculations and the equations used, indicating uncertainty about the methodology.

Areas of Agreement / Disagreement

Participants express uncertainty regarding the correctness of the calculations and the necessity of unit conversions. No consensus is reached on the validity of the approach or the answers provided.

Contextual Notes

Participants do not clarify the assumptions behind their calculations or the definitions of the variables used. The discussion lacks resolution on the correctness of the steps taken.

ra180
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Homework Statement



Car (A) C180K WITH A 1.8 litre supercharged spark ignition, Maximum power output 104kw, based upon standard fuel efficiency test a vehicle with this engine would consume 6.1 liters over 100k journey

Car (B) C220 CDI with a 2.0 litre turbocharged diesel engine. Maximum output =109kw, based upon the standard fuel efficiency test a vehicle with this engine would consume 5.7 liters of Diesel over a 100km journey.

QUESTION: Calculate average fuel energy consumed per kilometer in the standard fuel efficiency test for each vehicle and hence determine which version of the vehicle had the most fuel efficient engine


Homework Equations



Convert miles per 100km to miles per gallon= 100*lpg/ kmpm*lp100km

lpg= litre per gallon= 4.54609188

kmpm= kilometers per mile= 1.609344

lp100km= litre per 100km

Variables given 1 mile = 1.609 km, 1 gallon = 4.546 litre


The Attempt at a Solution



Convert miles per 100km to miles per gallon= 100*lpg/ kmpm*lp100km

For Car A= 46.30 Car B = 49.56

Car (A) 104000 x 1800 = 187200000

187200000/ 1x10^6 =187.2

E gasoline = 187.2/(46.30 x 1.609km x 1/4.564)

E= gasoline= 11.47MJ/km < ANSWER

I DON'T WANT WASTE TIME ILL TRY CAR B WHEN I'M SURE MY STEPS ARE RIGHT FOR CAR A
 
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Why convert fro nice SI units to British/American units?
 
I needed to convert it for my equation. Is my answer correct or not?
 
ra180 said:
I needed to convert it for my equation. Is my answer correct or not?

What equation?
 

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