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Old 06-19-2008, 04:43 PM   #85
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Originally Posted by COLORADO_CAMPER View Post
I just didn't and still don't understand how an airspeed indicator helps achieve that.
It's really quite simple.

You are in Chicago and you're heading for a vacation in California. You check your air speed indicator and find you have a headwind. You turn around and go vacation in New York instead, getting a tailwind and therefore better mileage.

The trick to getting back to Chicago is to pack up the trailer and start heading west. If the ASI shows headwind, pull over and set up camp. Repeat until the ASI indicates a tailwind, then go home.
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Old 06-19-2008, 05:34 PM   #86
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Originally Posted by Wayne&Sam View Post
It's really quite simple.

You are in Chicago and you're heading for a vacation in California. You check your air speed indicator and find you have a headwind. You turn around and go vacation in New York instead, getting a tailwind and therefore better mileage.

The trick to getting back to Chicago is to pack up the trailer and start heading west. If the ASI shows headwind, pull over and set up camp. Repeat until the ASI indicates a tailwind, then go home.

Funny and, yes, that is my point ... so the wind is blowing - what are you going to do about it? You basically have three choices: stay where you are, go another direction or buck up and deal with it.

No, I would have to say that installing an airspeed indicator in your truck is not going to go a long way in saving you money. It might suggest that your gas mileage would improve if you drove in a different direction but it isn't going to help get you where you need to go and save you gas and money in doing so. And, no, I don't need to try it to be convinced of its merits, or lack thereof.

-Kevin
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Old 06-19-2008, 05:39 PM   #87
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Years back, 25 or so, we would install an air dam (ground F/X) below the front bumper. This would help deflect some of the air that would get trapped under our M/H.
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Old 06-19-2008, 05:56 PM   #88
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Was it a sliding canopy one? Didn't they later make door slammer?

What I really want is an airspeed indicator for my bicycle. It would make me feel better when I am slowed down to 10 or 11 mph in a strong headwind.
Ah yes, it was a sliding canopy. Bummer, but other than that, it was and still is an outstanding aircraft. Not fast, but rugged. One of the nice things was the cabin space. You could easily go from the front seats to the back, by just sliding between the front seats.

Ours trued out at 154 mph and used 10 gallons per hour, and carried 60 gallons. After 5 hours, it was time to get back on the ground, for more reasons than just fuel.

I installed an evaporator cooler on the canopy shelf. Even on very hot days, you had to turn the fan speed down, so you didnt freeze your body. FAA approved the installation. That was a lot cheaper than a regular AC.Keep in mind, that the higher the altitude, the less humidity.

I really miss it. As you know, when your in the sky, as PIC, the world is soooo peaceful., even in controlled air space.

Andy
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Old 06-19-2008, 06:46 PM   #89
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Moderator's note:
I've merged another thread to this one, in an attempt to keep this information in one place. With any luck, this will make further searches easier to conduct for fuel mileage related questions.
We now return you to your regularly scheduled thread, already in progress:
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Old 06-19-2008, 09:12 PM   #90
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I installed a K&N Cold Air Intake that boosted me about 3 MPG around town and even as much as 6 MPG on the highway. ...
I just got my first round of K&N filter results. My MPG-O-METER has always averaged 3 mpg on the optimistic side under light hwy use. It jumped up a solid 1 mpg over the last 600 miles with the new filter BUT at fill-up the actual usage is exactly the same....
I now am 4 mpg overstated but I never have to buy another filter
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Old 06-20-2008, 03:18 PM   #91
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I see the use of an ASI (non-TSO'd) as a good idea. Along with, for a gas motor: vacuum gauge, fuel flow meter and tachometer.

For a diesel: EGT, Fuel Flow, Boost .

I'll try to get them the same size, mount them together, and rotate the gauges (analog type) so that the needles all point 12 o'clock under optimum conditions; then, if I want, vary speed or gear choice or whatever to conserve fuel. In other words, to make simple and scanning is quick, no interpretation needed.

I appreciate the idea, Andy, I'll never forget the day I was driving a V8-440 Chrysler through central Texas, unknowingly, into a headwind of 40-50-60 mph. The car was new to me and I couldn't understand why the mpg was dropping so fast (running all kinds of scenarios in my head); that is, until I stopped for coffee and learned I had been driving in the edges of a tornado.

I think an ASI is a great idea!
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Old 06-20-2008, 04:28 PM   #92
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I installed an evaporator cooler on the canopy shelf. Even on very hot days, you had to turn the fan speed down, so you didnt freeze your body. FAA approved the installation. That was a lot cheaper than a regular AC.Keep in mind, that the higher the altitude, the less humidity.
Andy
That's a great idea. I used an evaporative cooler when I lived in the Texas panhandle. Worked great there too.

There is a very nice sliding canopy Navion at the Pine Bluff airport where a friend has his plane. There are a couple more that I know of in Arkansas.
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Old 06-20-2008, 05:50 PM   #93
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I've mentioned this before, so forgive me if you've seen it. Heavy Duty Trucking is an industry magazine and much of the recent content is about fuel economy.
The recent issue (contents in the link above) has a particularly extensive article. I haven't totally digested it yet.
Some things are particularly interesting, including a comparison drive off between two editors. One had a higher top speed, higher average speed, and higher fuel economy than the other.

They talk extensively about shifting, about when to and when not to use cruise control, things of that nature.

They do not (at least so far as I have read) mention an EGT, and I have to wonder if an EGT in an EGR engine with aftertreatment gives you meaningful information.
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Old 06-20-2008, 06:43 PM   #94
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Ah yes, it was a sliding canopy. Bummer, but other than that, it was and still is an outstanding aircraft. Not fast, but rugged. One of the nice things was the cabin space. You could easily go from the front seats to the back, by just sliding between the front seats.
... Andy
Well, son-of-a-gun. My dad sold his sliding canopy Navion about seven years ago. Now all he has left is the little Aercoup, and it's currently got wings and tail section off so that he can repaint the whole thing. Heaven knows if he'll ever get it done, though.

Lynn
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Old 07-03-2008, 08:20 PM   #95
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On a gas engine a vacuum gauge tells you how much power is being lost to intake pumping loss. A lot of energy is lost when the piston draws air in against the vacuum of the manifold. Diesels don't have any restrictions to air intake, so they don't have any significant intake pumping loss. You can eliminate the pumping loss in a gas engine by removing the throttle plates, which ofcourse gives you no way to control the engine's power. Run the highest gear you can without making the engine knock.

Roughly speaking a 10% increase in speed results in a 21% increase in fuel consumption to cover the same distance. That's energy lost to wind resistance, so this doesn't apply when you're towing up a hill. On that flat this is very accurate above about 75km/h, and I've personally tested this by tapping into the air flow sensor signal on my car.

Make sure your vehicle rides level. The aerodynamics can change a lot, and this hurts both fuel consumption and handling.
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Old 07-04-2008, 10:37 AM   #96
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On a gas engine a vacuum gauge tells you how much power is being lost to intake pumping loss. A lot of energy is lost when the piston draws air in against the vacuum of the manifold. Diesels don't have any restrictions to air intake, so they don't have any significant intake pumping loss. ...
Uh, fuel economy in a gas engine is highest when the vacuum is high. Mainly because the engine is turning as slowly as possible. Gas engines require approximately 14.7 parts of air to one part of gasoline (Air-fuel ratio - Wikipedia, the free encyclopedia) to function properly. No matter what the vacuum reading (or power load) is. Diesel engines do not have this requirement. Power is regulated by pumping more or less fuel, the mixture is irrelevant. Diesels get better fuel economy by pumping less fuel most of the time.
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Old 07-05-2008, 07:12 AM   #97
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Uh, fuel economy in a gas engine is highest when the vacuum is high. Mainly because the engine is turning as slowly as possible.
Fuel economy goes up when the vacuum goes down.

Edit to be more precise: The pumping loss of a gasoline engine goes down when the vacuum goes down.

For the record turbo diesels do have an air fuel ratio as well, typically called the excess air ratio. Depending on the fuel grade it can be from 1.5:1 for your typical consumer diesel to 3:1 for large diesels in container ships.
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Old 07-05-2008, 11:33 AM   #98
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Fuel economy goes up when the vacuum goes down.
Sorry, but exactly wrong. When the vacuum goes down, you are opening up the throttle. You are implying that you get your greatest economy with your vehicle floorboarded!
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Originally Posted by canadianguy View Post
Edit to be more precise: The pumping loss of a gasoline engine goes down when the vacuum goes down.

For the record turbo diesels do have an air fuel ratio as well, typically called the excess air ratio. Depending on the fuel grade it can be from 1.5:1 for your typical consumer diesel to 3:1 for large diesels in container ships.
I gotta admit, "pumping loss" is a new one to me. I can see that there is some inherent loss of energy when pulling a vacuum, but still, the higher the vacuum the less fuel you burn, period.

Also, not all diesels are "turbo" diesels. Old Detroit Diesels had a mechanical supercharger (the 6-71 supercharger became famous on 426 hemi drag racers in the 50s and 60s) and were two-stroke diesels. Some other diesels have no supercharging at all.
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