Archives

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.

[QUOTE=jlI 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.[/QUOTE]


More oxygen in the air means more fuel will have to be burned to keep the A/F ratio to the set point


As for dropping a match into gas: :eek::eek:

JL, your experiment showed that cold air does make more power. It did not show anything about economy. If you were able to set up a very sensitive flow-meter on the feed to a carbureted engine, or two of them on the feed and return fuel lines of an injected engine, you might have been able to detect something about the fuel used. For an injected engine, monitoring the pulse widths of the injector signal would also give you some idea of the amount of fuel going in. But measuring no-load RPM doesn't tell you about the fuel.

WOT (Wide-Open Throttle) is also a condition that doesn't have much to do with everyday driving and fuel economy. What you really need to do is figure out how much power is used to propel a car at freeway speeds (which is on the order of 10 HP), then see how efficiently an engine with a throttle can make 10 HP. It turns out that, due to "pumping losses" at the throttle plate, most gasoline engines tend to make that ~10 HP more efficiently with high intake air temps.

The experiment is a good one, but it does not actually ask the question that you thought it was asking.

-soD

JL, most of us here find that we get better fuel economy at higher ambient air temperatures, as you originally expected. Just look at most people's mileage logs and you will see better mpg numbers in the summer.

Note my observations in the chart below - higher mpg at higher temperatures and lower speeds. Can you image the mpg this car would get in Texas going the new speed limit of 85 mph (off the chart :ccry:):
http://www.cleanmpg.com/photos/uploads/3586/Cobalt_mpg.JPG

You can see how the data shown above was collected at:
http://www.cleanmpg.com/forums/showthread.php?t=24278

Cooler air will not help improve efficiency on todays gasoline engines.

It will improve efficiency on diesel engines though.

I checked out some charts from diesel trucks and cars in our Clean MPG Mileage Logs. Look for people who have logged for over a year. Not sure where these vehicles reside and if temperatures are very cold in the winter:

Here is a chart from a Jetta TDI:

http://www.cleanmpg.com/garage/images/cha530.png

Here is a Ford 350 truck:

http://www.cleanmpg.com/garage/images/cha839.png

They seem to get better mileage in the warmer months.

Gas get better mileage in summer because of summer gas too. To the best of my knowledge nobody here has found out how much summer gas affects mileage.

Gas get better mileage in summer because of summer gas too. To the best of my knowledge nobody here has found out how much summer gas affects mileage.

I agree that the summer blend produces better MPG overall, but I also notice that on the warm days this past month that mileage improves quite a bit despite the winter fuel. So as previous ones have said, warm air is conducive to better MPG.

I agree that the summer blend produces better MPG overall, but I also notice that on the warm days this past month that mileage improves quite a bit despite the winter fuel. So as previous ones have said, warm air is conducive to better MPG.
Agreed. My Prius seems to make a jump in FE at around 40F then another jump around 60-70F. I think it has a lot to do with increased combustion efficiency along with the fact that warmer air isn't as dense and takes less effort for the car to physically move through the air. My glide times are significantly longer in warmer temps even with the same psi in the tires ie, I can glide farther in 70F at sidewall-max;) than I can at 25F.

My personal feeling (just a guess though!) is that the tire temps, engine temps, and extra air resistance of the denser air play more of a role than induction temps do.

I believe there are people on ecomodder.com who have A/B tested warm air intakes. Some have seen benefits, others have not.

-soD

As the others have said, warmer intakes generally give better economy.

Here's my history. Especially notice the last two years. (red and yellow)
http://www.cleanmpg.com/garage/images/cha301.png

Could the wheel bearings, grease, and transmissions work more efficiently at warmer temperatures?

I have also seen longer glides at warm temperatures and that could be measured independently of engine efficiency. Sounds like an experiment we need to conduct.

Do the tire companies publish rolling resistance of their tires at different temperatures?

Do all of these efficiencies, and summer gas, just make it look like the engine is more efficient in the summer (the car certainly is). Perhaps JL is correct in his original assumption that the engine is more efficient in cold temperatures.

As the others have said, warmer intakes generally give better economy.

From what I understand, it seems that warmer intakes warm up the car quicker, and that was how the fuel economy increases.

Air itself is more dense the colder it is. IE: friction

Air itself is more dense the colder it is. IE: friction

For both aerodynamic resistance and the pumping losses of the engine.

My hunch is our visitor won't be directing his teacher to CleanMPG for backup support. :eyebrow:

I have a pretty jenky Warm air intake setup and I did notice in the winter once the intake temp got up around 70 degrees Fahrenheit that my coasting mpg did jump significantly. However once it warms up (80 degree days) all my car liked to do was detonate. As for any signifigant mpg increase I think I saw roughly 1 mpg overall.

Thinking about this now I may try running premium in there to see if I can get rid of detonation and have a intake temp of 150 or so in the summer.