Effect of Alcohol Percentage in Gasohol on Engine Output

PURPOSE

The purpose of this experiment was to determine how the alcohol percentage in gasoline affected the power output of an internal combustion engine. 

I became interested in this idea when I talked to Chris Mottet about measuring the amount of power coming from an engine.

The information gained from this experiment could help people in the world know how much power their gasoline alcohol mixture will give them. It will help them make decisions about fuel efficiency.

HYPOTHESIS

My hypothesis was that as the alcohol content increased; the output per gallon would decrease.

 I based my hypothesis on an article on the Internet by David Ostlie who wrote about gasoline vs. ethanol. “On a volumetric basis ethanol yields 83,910 BTU’s/ gallon of thermal energy from combustion. Gasoline yields 124,800 BTU’s/ gallon of thermal energy. It becomes obvious that a dollar’s worth of gasoline will propel you 1.5 times farther than a dollar’s worth of ethanol.” 

EXPERIMENT DESIGN

The constants in this study were:

• The engine
• The generator
• The type of gas
• The ethanol
• The load on the engine
• The number of trials

The manipulated variable was the percentage of ethanol in the gasoline.

The responding variable was the power output of the engine. 

To measure the responding variable I timed how long a fixed amount of gasohol would power the engine.  

MATERIALS

QUANTITY	ITEM DESCRIPTION
1	Generator w/ Engine
2400 ml	Gasoline
600 ml	Ethanol
1  Per Person	Pair of gloves
1  Per Person	Pair of glasses
1	Stop watch
1	Load
1	Measuring Cup
5	Cups for Gasohol

PROCEDURES

1. Put on safety glasses and gloves.

2. Create the five mixtures of gasohol in clean-labeled cups.

3. To create the mixtures you follow these rules. Make two of each batch for more accuracy. 

A. 10%= 30 ml ethanol + 270 ml gas= 300 ml of 10% ethanol mix.

B. 15%= 45 ml ethanol + 255 ml gas= 300 ml of 15% ethanol mix.

C. 20%= 60 ml ethanol + 240 ml gas= 300 ml of 20% ethanol mix.

D. 25%= 75 ml ethanol + 225 ml gas= 300 ml of 25% ethanol mix.

E. 30%= 90 ml ethanol + 210 ml gas= 300 ml of 30% ethanol mix.

4. Place the engine in a safe well-ventilated spot.

5. Make sure there is 10%, 15%, 20%, 25%, and 30% written on the appropriate cups.

6. Prior to the first test put 300 ml of pure gasoline in and run dry. This is to preheat the engine to keep all of the tests the same temperature.

7. Pour 300 ml of gasohol into the engine.

8. Start the engine (with no load).

9. Make sure your load is on after you turn on the engine.

10. Perform the first experiment on the gasohol with 10% ethanol.

11. Clock how long it takes to run the engine under load until it runs out of gasohol.

12. Record the information you gathered from your experiment.

13. Perform the experiment using the same mixture two more times for better accuracy.

14. Do the experiment and follow numbers 8-14 for the rest of the gasohol mixtures.

RESULTS

The original purpose of this experiment was to determine how the alcohol percentage in gasoline affected the power output of an internal combustion engine.

The results of the experiment were that the mixtures of gasohol 10% through 25% did not make any difference compared to the gasoline (control.) When we got to thirty percent ethanol the output decreased by 25.6%.  

  
CONCLUSION

My hypothesis was that as the alcohol content increased; the output per gallon would decrease.

The results indicate that this hypothesis should be accepted, because when we got up to 30% ethanol there was a 25.6% decrease.

Because of the results of this experiment I wonder what the output per gallon would be on a specially modified engine that is made to take more alcohol than gasoline. I wonder if it would get better output per gallon than a regular gasoline engine.  

If I were to conduct this project again I would make my own modified gas tank. This would help me know that the engine burned the exact same amount of gasohol. I would also conduct more trials.

Researched by ---  Avery M