How to calculate fuel to accelerate a vehicle

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SUMMARY

This discussion focuses on calculating the fuel required to accelerate a vehicle, considering factors such as fuel type, incline, and energy conversion efficiency. For gasoline, the oxidation of 1 gram releases approximately 44,000 Joules, while 1 U.S. gallon yields about 120 million Joules. The efficiency of a conventional spark-ignited internal combustion engine is around 20%. Key calculations involve potential energy (W = mgh) and kinetic energy (W = 1/2mv), with fuel consumption estimates varying based on engine type and fuel, particularly noting that modern diesel engines produce 18 to 20 horsepower per gallon of fuel burned per hour.

PREREQUISITES
  • Understanding of energy conversion (Joules to horsepower)
  • Familiarity with basic physics concepts (potential and kinetic energy)
  • Knowledge of brake specific fuel consumption (BSFC) metrics
  • Awareness of fuel types and their energy content (gasoline, diesel, LPG)
NEXT STEPS
  • Research the principles of energy conversion efficiency in internal combustion engines
  • Learn how to calculate fuel consumption based on vehicle weight and incline
  • Explore the impact of different fuel types on engine performance and efficiency
  • Investigate advanced calculations for brake specific fuel consumption (BSFC) in various engine types
USEFUL FOR

Automotive engineers, mechanical engineers, physics students, and anyone involved in vehicle performance optimization will benefit from this discussion.

IMK
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Hello,
I am trying to calculate how much fuel (petrol/diesel/LPG) it takes to accelerate a vehicle and well to cut a long story sort I seem to be getting my units mixed up also whether I should us small or big calories. Lastly is the incline and issue that I also need to consider and how do I apply it please?

So was wondering if someone could get me off in the right direction please?

Many thanks in advance

PS This is NOT a home work question!
 
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For gasoline, oxidation of 1 gram releases about 44,000 Joules of heat. For 1 U.S. gallon, 120 million joules. But a conventional spark-ignited internal combustion engine, the conversion efficiency is typically ~20%.

The attached thumbnail of a brake specific fuel consumption (BSFC) plot shows the efficiency of a typical 2.7-L gasoline engine as a function of RPM and torque.

Bob S
 

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If you are accelerating a vehicle up an incline, the resultant HP used is the change in potential energy plus the change in kinetic energy. Assuming you start from a standstill and zero reference position:

for the potential energy, W = mgh; for the KE energy, W = K= 1/2mv
and velocity (v) is at.

So you should expect to consume more fuel for greater height (steeper incline) and/or greater acceleration.

You'll also have to get an estimate of fuel consumption to produce a HP...that depends on the type of fuel, such as gas or diesel, type of engine, and a lot of other factors...but a reasonable average for modern diesel engines is that they produce 18 to 20 hp per gallon of fuel burned per hour.
 

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