Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

How to calculate fuel to accelerate a vehicle

  1. Jul 28, 2010 #1

    IMK

    User Avatar

    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!
     
  2. jcsd
  3. Jul 28, 2010 #2
    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
     

    Attached Files:

  4. Jul 28, 2010 #3
    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.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook