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Old 04-20-2013, 07:36 AM
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Richard Martin Richard Martin is offline
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I noticed something very interesting yesterday about my fuel mileage

I took all of the equipment off of my trailer yesterday because I had to go and pick up some 12 foot long items for the house. Normally I get around 13 MPG with the equipment loaded up on the trailer. I figured that since I removed about 1800 pounds, give or take a few pounds, that my mileage would jump up to around 15 to 16 MPG. Boy was I surprised when the mileage actually dropped to 12.5 MPG.

I think that even though the gate is made up of expanded metal, it is still acting like a big old sail and creating a lot of drag. When the mowers are on the trailer, it breaks up the wind and reduces the drag.

I'm going to take the gates off of the trailer today and see if that makes a difference. If my mileage jumps up I'm going to try to make some sort of deflector to try and get the air up and over the equipment and tail gates on the trailer.

The point of all of this is to try to get better gas mileage. Just switching from my 1995 F150 to this 2007 Chevy 1500 resulted in a 30% increase in fuel mileage. The Ford got 10 MPG and the Chevy is getting 13 MPG. I had seriously considered going to a 12 foot trailer with a single axle because of the reduced weight. But if weight is not the problem, then the tailgate must be.

What do you guys think?
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Old 04-20-2013, 08:10 AM
Darryl G Darryl G is offline
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I think your sampling is insufficient.
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Old 04-20-2013, 09:31 AM
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Richard Martin Richard Martin is offline
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Originally Posted by Darryl G View Post
I think your sampling is insufficient.
I went about 30 miles over the exact same roads that I use on my mowing route. Granted the sampling was small but I don't think there would be much variation of the results with a greater distance. If I was at 12.5 MPG and the rate was climbing then more driving was required to obtain a good result. The mileage was actually declining as I drove farther. I have instant and average mileage results from a Ultra Gauge. http://www.ultra-gauge.com/ultragauge/index.htm
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Old 04-22-2013, 12:15 AM
CL&T CL&T is offline
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Originally Posted by Richard Martin View Post
... I have instant and average mileage results from a Ultra Gauge. http://www.ultra-gauge.com/ultragauge/index.htm
Cute but what is the accuracy of that thing? You are talking 0.5-0.7 mpg here which is very small. The ONLY way to check gas mileage with any reasonable accuracy is by taking the actual gallons used and the mileage driven over several tankfulls. The MPG computers in new vehicles are at best a rough estimate as is that Ultraguage which probably works the same way. Seeing that small a variation over only 30 miles on a device like that is meaningless.
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Old 04-22-2013, 06:35 AM
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Richard Martin Richard Martin is offline
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Originally Posted by CL&T View Post
Cute but what is the accuracy of that thing? You are talking 0.5-0.7 mpg here which is very small. The ONLY way to check gas mileage with any reasonable accuracy is by taking the actual gallons used and the mileage driven over several tankfulls. The MPG computers in new vehicles are at best a rough estimate as is that Ultraguage which probably works the same way. Seeing that small a variation over only 30 miles on a device like that is meaningless.
The UltraGauge is tunable. If the actual mileage is different than what the UltraGauge says, you can fine tune it so it reads correctly. You can't do that with the factory programs.

I've been tracking mileage for a very long time the old fashioned way. The UltraGauge in my setup is reading just about perfect.
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Old 04-22-2013, 11:44 AM
CL&T CL&T is offline
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Quote:
Originally Posted by Richard Martin View Post
The UltraGauge is tunable. If the actual mileage is different than what the UltraGauge says, you can fine tune it so it reads correctly. You can't do that with the factory programs.

I've been tracking mileage for a very long time the old fashioned way. The UltraGauge in my setup is reading just about perfect.
Tunable TO WHAT? What you think your mileage should be? Even if you adjusted it to the number a long term "old fashioned" calculation gave you there is no guarantee the next one would be the same and certainly 0.5-0.7 is well within the margin of error. There are so many variables that effect gas mileage that it would be impossible to get the accuracy you claim on the fly without a sophisticated PC measurement system with actual flow meters in the fuel lines, accurate temperature measurements and dead on distance travelled. Even then it's going to have to be averaged because it's never going to be repeatable.
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Old 04-20-2013, 08:12 AM
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CreativeLawncareSolutions CreativeLawncareSolutions is offline
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The Mythbusters have already tested this. The conclusion...

Closing the tailgate actually improves fuel efficiency because it creates a type of airflow called a separated bubble within the bed of the truck. As wind rushes over the moving truck, that bubble of slow-moving air deflects it over the raised tailgate. By guiding surrounding air over and across the bed of the truck, that vortex effect prevents added drag.

However, driving with the tailgate open eliminates the bubble effect, pulling the air toward the truck bed and creating more drag rather than deflecting the wind. Some gas-conscious pickup drivers still swear by leaving their tailgates open, but science sides with leaving it up.
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Old 04-20-2013, 09:14 AM
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Snyder's Lawn Inc Snyder's Lawn Inc is offline
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Quote:
Originally Posted by CreativeLawncareSolutions View Post
The Mythbusters have already tested this. The conclusion...

Closing the tailgate actually improves fuel efficiency because it creates a type of airflow called a separated bubble within the bed of the truck. As wind rushes over the moving truck, that bubble of slow-moving air deflects it over the raised tailgate. By guiding surrounding air over and across the bed of the truck, that vortex effect prevents added drag.

However, driving with the tailgate open eliminates the bubble effect, pulling the air toward the truck bed and creating more drag rather than deflecting the wind. Some gas-conscious pickup drivers still swear by leaving their tailgates open, but science sides with leaving it up.
You need to read better OP is talking about trailer tailgate not a pickup
Stay on the subject on hand
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Old 04-20-2013, 09:22 AM
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Richard Martin Richard Martin is offline
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Quote:
Originally Posted by CreativeLawncareSolutions View Post
The Mythbusters have already tested this. The conclusion...

Closing the tailgate actually improves fuel efficiency because it creates a type of airflow called a separated bubble within the bed of the truck. As wind rushes over the moving truck, that bubble of slow-moving air deflects it over the raised tailgate. By guiding surrounding air over and across the bed of the truck, that vortex effect prevents added drag.

However, driving with the tailgate open eliminates the bubble effect, pulling the air toward the truck bed and creating more drag rather than deflecting the wind. Some gas-conscious pickup drivers still swear by leaving their tailgates open, but science sides with leaving it up.
The tailgate on a pickup is a whole different scenario. The tailgate on the trailer cannot create a bubble because there are no sides on the trailer to contain the air pressure that creates the "bubble". The tailgate on a truck is also 8 feet behind the cab and lower than the cab. The tailgate on my trailer is 29 feet behind the cab of the truck.

I know exactly what the bubble in the truck bed is. This is the same type of thing that happens with race cars when they draft. But just like with drafting, the closer the object is that is trying to draft, the greater the effect will be.

This is easy to confirm. I'll just take the gates off of the trailer and see if the mileage increases. If it increases then the tailgate is causing drag. If it doesn't increase, then I continue to look for a 6 by 12 trailer.
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Old 04-20-2013, 09:57 AM
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CreativeLawncareSolutions CreativeLawncareSolutions is offline
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Quote:
Originally Posted by Richard Martin View Post
The tailgate on a pickup is a whole different scenario. The tailgate on the trailer cannot create a bubble because there are no sides on the trailer to contain the air pressure that creates the "bubble". The tailgate on a truck is also 8 feet behind the cab and lower than the cab. The tailgate on my trailer is 29 feet behind the cab of the truck.

I know exactly what the bubble in the truck bed is. This is the same type of thing that happens with race cars when they draft. But just like with drafting, the closer the object is that is trying to draft, the greater the effect will be.

This is easy to confirm. I'll just take the gates off of the trailer and see if the mileage increases. If it increases then the tailgate is causing drag. If it doesn't increase, then I continue to look for a 6 by 12 trailer.
You never said your trailer didn't have sides. My trailer has sides.

No sides, no bubble. Obviously.
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