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Old 04-09-2011, 07:42 AM   #1
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Post My 9th grade science project. improve fuel economy and performance

Hypothesis; IF YOU ALTER THE TEMPERATURE OF THE AIR GOING INTO A GASOLINE COMBUSTION ENGINE THEN THE ENGINE'S EFFICIENCY WILL BE AFFECTED

RESULTS; RPMs At Different Celsius Temperatures:
10 Degree Air Temperature- full throttle 11032; idle 1764
-25 Degree Air Temperature- full throttle 12395; idle 1982
40 Degree Air Temperature- full throttle 10074; idle 1611
125 Degree Air Temperature- full throttle 8946; idle 1430

By changing the temperature of the air going into the engine I was able to prove that colder air leads to better fuel economy while maintaining or improving performance.

Abstract:
How Air Temperature Affects the Efficiency of a Gasoline Engine
By: Jake Levine
In light of the events in the Middle East over the past month the US needs to lessen its demand on foreign oil. When Middle East countries are in turmoil or fighting wars and rebellions such as with Mubarak in Egypt or Kaddafi in Libya the price of oil goes up. When the countries who own the oil need the oil to fight wars, to prove a point, or to threaten other countries by limiting the amount of oil released the price of the oil goes up. When the price of oil goes up the price of gas goes up. If we limit the amount of oil we get from the Middle East when the countries in the Middle East decide to limit the amount of oil released the price of our fuel would not be as affected.
By improving fuel economy of cars and trucks and even motorcycles we reduce the demand on oil. Most car companies try to improve fuel economy in new cars by reducing weight, changing gear ratios, slowing down throttle response, and even shutting down the engine at red lights. These actions might even be overdoing it, when something as simple as changing where cars intake there air from might-based on my results- be able to improve fuel economy.
I found that the temperature of the air did in fact have an effect on an engine. But instead of hot air making it go faster like I expected it did the opposite, the colder the air the faster the flywheel span. I suspect this is due to more oxygen per square inch in cold air than in hot air.
To test this theory I decided to do one more experiment. I measured specific amounts of super 93 gasoline into containers and dropped a match into the gas. I then recorded the explosion and measured how high the explosion was.
In all three sets of the second experiment the fuel burnt in the cold was more than noticeably bigger than the warmer explosions. This would leave me to believe that at sea level colder air is more combustible than warm air.
By moving the air intake of a car from the engine bay that can be over a few hundred degrees to an outside place such as the front bumper or fenders can greatly improve efficiency and or performance.
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Old 04-09-2011, 08:34 AM   #2
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Re: My 9th grade science project. improve fuel economy and performance

I admire the work and interest you put into your project.

Its nice to see the "next generation drivers" with real concerns on fuel economy and performance.

What engine did you use for your experiment, and was it EFI or Carburetor?

When you did your rpm test did you measure fuel that was consumed?

I won't be able to check back to this thread until latter tonight. I'm getting ready to do a test run of 600+ miles. But I'm looking forward to your information.
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Old 04-09-2011, 10:41 AM   #3
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Re: My 9th grade science project. improve fuel economy and performance

Thank You
I used a 2 stroke engine and the fuel going into the carb was kept a constant.
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Old 04-09-2011, 01:36 PM   #4
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Re: My 9th grade science project. improve fuel economy and performance

how many other forums you gonna post this on??
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Old 04-09-2011, 02:47 PM   #5
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Re: My 9th grade science project. improve fuel economy and performance

lol i thought this was a known fact colder air = better performance... is nice to see your proving it tho. Nice work

dirt track racing and drag racing will and have "cheated" by putting dry ice in the airbox during a race :P

that's usually why most cars if not all have the airbox sucking in air behind the grille. or headlight or somewhere other than engine bay

hell even ye ol chevette has it out to the grille.
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Old 04-10-2011, 08:54 AM   #6
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Re: My 9th grade science project. improve fuel economy and performance

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Originally Posted by jl22996 View Post
Thank You
I used a 2 stroke engine and the fuel going into the carb was kept a constant.

Some food for thought.

I'm not to sure what size engine your testing but lets say for calculating reasons its a 1.0L.

Example 1)
a 1.0L four stroke engine at 10,000 rpm with a VE of .85 and a intake temperature of 50*F will flow 11.62 lbs/min of air.

Example 2)
a 1.0L four stroke engine at 10,000 rpm with a VE of .85 and a intake temperature of 257*F will flow 8.26 lbs/min of air.

So you see that the extra 3.36 lbs/min of air can help the engines efficiency and pull past the 10,000 rpm mark.

Your carburetor and main jet adds fuel base on the amount of air in cfm, not weight that moves across the venturi. So with the examples above the same amount of fuel will be flowed on both examples. So what will change is the air to fuel ratio.

So with the examples above.

Example 1) will have a air fuel ratio of 14.7

Example 2) will have a air fuel ratio of 10.5

This very rich condition of 10.5 will slow the flame speed down during combustion. A slow flame speed is a huge determent in the higher rpm range. Because the pistons starts to catch or out accelerate the flame front. This is why you need more ignition advance at a higher rpm.
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Old 04-10-2011, 09:16 AM   #7
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Re: My 9th grade science project. improve fuel economy and performance

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Originally Posted by pgfpro View Post
Some food for thought.

I'm not to sure what size engine your testing but lets say for calculating reasons its a 1.0L.

Example 1)
a 1.0L four stroke engine at 10,000 rpm with a VE of .85 and a intake temperature of 50*F will flow 11.62 lbs/min of air.

Example 2)
a 1.0L four stroke engine at 10,000 rpm with a VE of .85 and a intake temperature of 257*F will flow 8.26 lbs/min of air.

So you see that the extra 3.36 lbs/min of air can help the engines efficiency and pull past the 10,000 rpm mark.

Your carburetor and main jet adds fuel base on the amount of air in cfm, not weight that moves across the venturi. So with the examples above the same amount of fuel will be flowed on both examples. So what will change is the air to fuel ratio.

So with the examples above.

Example 1) will have a air fuel ratio of 14.7

Example 2) will have a air fuel ratio of 10.5

This very rich condition of 10.5 will slow the flame speed down during combustion. A slow flame speed is a huge determent in the higher rpm range. Because the pistons starts to catch or out accelerate the flame front. This is why you need more ignition advance at a higher rpm.
I used a 49cc engine.
Im not really following what you saying bc Im not exactly sure what difference the air to fuel ratio makes.
My line of thought was that the colder the air the more dense and the more dense the more oxygen per square in and the more oxygen the bigger the combustion.
I also did more testing by burning a set amount of fuel in different temperatures and recording it on high speed and the fuel burnt in the colder air had a faster and higher initial flame and a higher sustained flame
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Old 04-11-2011, 07:48 AM   #8
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Re: My 9th grade science project. improve fuel economy and performance

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Originally Posted by jl22996 View Post
I used a 49cc engine.
Im not really following what you saying bc Im not exactly sure what difference the air to fuel ratio makes.
My line of thought was that the colder the air the more dense and the more dense the more oxygen per square in and the more oxygen the bigger the combustion.
I also did more testing by burning a set amount of fuel in different temperatures and recording it on high speed and the fuel burnt in the colder air had a faster and higher initial flame and a higher sustained flame
The "air fuel ratio" will be the outcome result due to the constant fuel flow amount based on how a carburetor is preset for fuel delivery based on air flow not air density. So with a less dense air you will get a richer air to fuel ratio in-which will produce a poorer combustion. If you could control the amount of fuel thats being used to keep a constant air to fuel ratio you would see better results in the amount of rpm that could be achieved. It would not be as high as your lowest temperture test but it would be a lot better, and help the FE part of your test based on BSFC.
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