# How to calculate fuel to accelerate a vehicle

1. Jul 28, 2010

### IMK

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. Jul 28, 2010

### Bob S

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:

• ###### BSFC5.jpg
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3. Jul 28, 2010

### Naty1

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.