MPG question.

[Shield Arc]

Wonder why they put grates in the road deck of the replacement bridge then?

Tacoma Narrows Bridge Collapse "Gallopin' Gertie" - YouTube

 

[clemsonfor]

Was thinking the same as others. Saw the mythbusters episode, but it was on a truck, not a dump trailer. There is no cab over the trailer to deflect the air so the results of their tests dont matter here. I use to remove my tialgate when i commuted 105 miles a day, never really noticed anydifference? As far as the mesh tailgates yep those things are like a sail, i remove mine when i can on long trips and use ramps or back up to a bank.

As far as mesh on a bridge it may have the same wind resistance as a solid deck as someone said (i dont know) but the mesh has to be lighter than solid reinforced concrete!!

 

[gumshu]

That's going to be an expensive trip.... $700 range.

 

[dodge man]

I agree, the mythbusters may or may not be valid for a dump trailer. I expect it wouldn't make a lot of difference either way, and like others have said, the trailer is designed to have the gates closed.

I believe mythbusters did two episodes, the first was just the tailgate up or down. The second one was the different mesh, vaned etc aftermarket tailgates, plus various bed covers. As I recall, nothing beat the stock tailgate in the up position. I was thinking even bed covers made the mileage worse, but not by very much.

 

[meburdick]

I agree, the mythbusters may or may not be valid for a dump trailer. I expect it wouldn't make a lot of difference either way, and like others have said, the trailer is designed to have the gates closed.

I believe mythbusters did two episodes, the first was just the tailgate up or down. The second one was the different mesh, vaned etc aftermarket tailgates, plus various bed covers. As I recall, nothing beat the stock tailgate in the up position. I was thinking even bed covers made the mileage worse, but not by very much.

I seem to recall from different readings of tests that they make no difference at all when they're the "soft cover" variety, and *may* make it a little worse when they're the solid type as those tend to add a decent amount of weight. Newer hard-cover varieties (like my BakFlip) are available in lightweight materials, so the impact may not be as bad.

 

[dodge man]

I think the main point is that bed cover companies tout their products as increasing the aerodynamics of the truck. At face value, this would make sense, but aero dynamics are funny. Just my opinion here, but I would say bed covers don't help the aerodyanmics of a truck, but probably don't hurt it very much either.

 

[clemsonfor]

I hate bed covers they make your truck either look like an old man truck and.. Also they are hard to get things out of when you want them. I was the tool boy in HS on summer for a carpenter. IT sucked to have to crawl into the bed or a truck or stuff your head in the crack between the two to reach tools in the front middle of the bed.

And yea they did a follow up episode testing other variables that the fans complained about. I remember soft bed covers with battons i think and hard ones and the net things of the 90s.

 

[meburdick]

I hate bed covers they make your truck either look like an old man truck and.. Also they are hard to get things out of when you want them. I was the tool boy in HS on summer for a carpenter. IT sucked to have to crawl into the bed or a truck or stuff your head in the crack between the two to reach tools in the front middle of the bed.

And yea they did a follow up episode testing other variables that the fans complained about. I remember soft bed covers with battons i think and hard ones and the net things of the 90s.

I have / had a lot of the same gripes as you. Check out the BakFlip F1 cover... That's what I have on my Tundra and it's an excellent cover.

 

[Raspy]

Don't think I've ever posted in this section before, generally stay in the welding section.
Anyway I got a 1,700-mile round trip coming up next week to pick up a tractor. I was wondering if I would get any better mileage if I left the doors open on my dump trailer? With diesel pushing $4.30 a gallon here on the west coast I need all the help I can get! Do you think this would help any, or do I just have wishful thinking.

Your trailer is not like a pickup bed at all. As stated by someone else, there is no cab in front of it and, on pickups, the beds taper in toward the rear. The trucks are more narrow at the back.

But the main thing is those trailer tail gates are positioned to "scoop" the air when open. Look at them. Heavy wind resistance. I would definitely close the gates.

I have a similar trailer and it had sides added that were three 2 X 12s high, about 35 inches on the front and both sides. Man that thing was hard to pull! I pulled one 2 X 12 off all the way around to reduce the height by 12 inches and it was way easier to pull.

 

[Shield Arc]

How about doing your own experiment? research.

I took your advice. Starting out on the trip I left the doors shut. Soon as I got out of the woods and onto the freeway (I-5) heading south I hit the on board over head mileage calculator to reset it. Only took a few minutes until I knew this was going to be an expensive trip!
That trailer is a slug to pull. Until now I've only used it here locally, 5 to 10 mile trips. About 200-miles into the trip, (south of Portland OR.) I pulled into a rest stop and tied the doors open, got back onto I-5 reset the overhead mileage calculator, soon as it settled down, it was 9/10 of a mile in the +, few miles later the calculator went up another 1/10. Opening the doors increased the mileage by 1-mile per gallon.
Someone please explain this to me. I stopped in Medford Oregon to fuel up. Got back onto I-5 reset the mileage calculator, when it settled down a 3-mile per gallon increase! Does Oregon have better diesel than Washington, and California? Same thing on the return trip. This also happened last September but with just the truck, no trailer. I may have to move to Medford just for the better mileage diesel!:laughing:

 

[Shield Arc]

But the main thing is those trailer tail gates are positioned to "scoop" the air when open. Look at them.

I'm going to remove the doors this morning for the return trip, it's just gotta help not having the "scoop"!

 

[Diamondpilot]

This is the issue with diesel fuel, there are no standards like gas. No "octante min rating". Diesel is rated in Cetane but the rating can very widely from refiner to refiner. Our diesel fuel in the states is junk when compared to what is available in other countries where its the primary fuel like Germany.

Chris

 

[Raspy]

It's hard to imagine a three MPG increase just from the fuel. What about the Siskiyous or the wind or your foot?

It is surprising how hard it is to pull those dump trailers! I think mine weighs around 4,500 lbs and it's wider than the truck.

Cetane ratings are about how easily the fuel ignites, not it's energy content, so mileage shouldn't vary much with a different number. And you had no way of knowing if one tank was higher or lower in cetane. Along the main corridors, like Interstate 5, and at truck stops, I think the fuel is pretty consistent. I've never seen a difference in mileage that I could say was caused by a difference in another state. I've even run all ratios of oil in mine. I even ran it for a while on son trip with straight lube oil with no diesel at all. Ran just the same as always.

 

[Shield Arc]

It's about 13-miles from Medford to Ashland, south of Ashland is where you start to climb, then you can watch the mileage drop! Yesterday on the return trip I filled up again in Medford, again the mileage went up. You don't hit any mountains for quite some time heading north out of Medford.

 

[MN Charlie]

With gasoline, different states mandate different "boutique" formulations and additives that even vary with the time of year. It's one of the reasons that fuel costs can vary so much from state to state (That and different taxes...) I wondered if diesel is subject to different formulations in different states too. Some quick searching turned up several articles about different states mandating new "low emission" diesel formulations so that could definitely enter into the equation.

I've noticed some pretty big differences in mileage on my gas engined truck depending on which state I purchased fuel.

 

[meburdick]

It's about 13-miles from Medford to Ashland, south of Ashland is where you start to climb, then you can watch the mileage drop! Yesterday on the return trip I filled up again in Medford, again the mileage went up. You don't hit any mountains for quite some time heading north out of Medford.

It's possible that the fuel you purchased in Medford could have:

- Been "fresher" (maybe they go through it at a high rate, turn the tanks over quick, and get their trucks from a very close port, etc)
- Had a slightly higher cetane rating than others, resulting in better burning efficiency (this is COMPLETE speculation based on my own personal observations that running premium gas in certain vehicles, under loaded conditions like highway driving, will sometimes yield better overall MPG).
- Had more lubrication additives allowing the motor to work more efficiently.

Dunno... Just complete WAGs at some things that *could* have been involved.