Gooseneck vs. Tag mileage

[MeanMrMustard]

I pull a big square, non-aerodynamic load of around 6K on a flat, open trailer behind a stock 2WD 7.3, 1999. The trailer weighs about 2300. The load sits up higher than the truck cab by about 2' or so. I have been told if I use a gooseneck, even though it is a heavier trailer, my mileage will increase 1-2 MPG. I know it is better on the truck, better on tires & better ride. But would MPG really increase? I am seeing around 11MPG with this load at 2K RPM. It is a crew cab truck & so only has a 29 gallon tank. Any increase would be helpful. Thanks for any advice.

[NickKent]

Is the trailer that you are pulling now a deckover? If it is, and your deck height would pretty much stay the same switching from one trailer to the other, then I don't think you're going to see much mileage difference. A goose definitely tows better and is safer, but with more weight I'd think you'd lose a little more in mileage. 8500 lbs on a bumper pull is not too bad. Especially if you use a wd hitch. I'd take the money your going to spend on a new trailer and add a larger fuel tank. Transfer Flow

[SmokeyWren]

What Nick said.

MPG is determined more by frontal area than by type of trailer hitch. So if you put the same load on the same height of trailer deck, then the frontal area won't change, and therefore you shouldn't see any change in MPG (at the same speed and driving conditions).

I've tried everything I can think of to improve MPG, but the only thing that works for me is to slow down. So if you don't want to slow down, then go for the bigger fuel tank from TransferFlow to increase your range.

With mine, towing my mid-profile 5er and grossing about 16k in the plains between west Texas and Ohio:
74 MPH = 2,150 RPM = 7+ MPG
70 MPH = 2,000 RPM = 9+ MPG
66 MPH = 1,900 RPM = 10+ MPG
62 MPH = 1,800 RPM = 11+ MPG
58 MPH = 1,700 RPM = 12+ MPG
55 MPH = 1,600 RPM = no go [img]/forums/images/%%GRAEMLIN_URL%%/crazy.gif[/img]

The problem is the stock 7.3L engine doesn't make enough HP below about 1,900 RPM, so I have to have a hot-rodded engine to cruise at 1,800 RPM without the tranny downshifting for every little bump in the road. (When the tranny downshifts, your MPG goes out the window). And 1,700 RPM, even with my hot-rodded engine, is okay only on almost-perfectly flat plains with no hills. So I usually lock the cruise control on 62 MPH and live with 11+ MPG. Yeah, my hot-rodded 7.3L loves to cruise with the big boys at 74 MPH, but I can't afford the hit in the pocketbook, so I usually slow down to 62.

[Crabby]

+1. Smokey is on the mark in his comments. Type of hitch will have little if any impact on mileage. Your foot on accelerator will have the greatest impact on MPG .... assuming a properly powered and tuned tow vehicle.

To get the performance out of mine, I had a Banks PowerPack installed. Although expensive, I have not regretted because driveability is so much better. Because the engine does not work so hard I had an increase in MPG, however, not enough increase to justify the expense. The entire package, (performance, mileage, less wear), and the "because I wanted it" factor, justified the expense.

I still get my best MPG @ 60ish mph .... by far !!

[T_Bone]

Hi MMM,

I was blessed with reading the aero-dymanic test results of a custom 5th/w RV mfg, before they removed the info from there website.

Ohh ya, I bookmarked the site but didn't copy the info, so I'm going by memory and the exact numbers will not be correct, but close(C) where noted:

Testing conditions: Same driver, truck (TV), fuel, time of day, test road (a flat road), trailer & TV tires and test direction with wind measurements:

The test: move the trailer at the same speed then at a set point let off of the fuel pedal until coasting to a stop then measure the distance.

Frontal was a huge disappoint as only 8% drag was decreased on a 8º back slope vs flat nose. Round corners were not that big of effect

The huge increase was the bottom of the trailer being skined with a 18" x 8ft@6º kick up at the rear corner edge, for a decrease of 18%(C) vs a open bottom.

There was more but this will cover your question. The only thing I would have added to my testing is humidity and temperature during tests.

On my test road and a recent seven State trip pulling 31kGCW, I averaged 13.86mpg due to my current driving style while trying to maintain 60mph on the flats.

On 7% grades, depending on the load weight, my speed was 30mph to 42mph with a time difference of only 15min for the grade length. Colorado grades.

My 27k mile life time fuel mileage is 15.2mpg that includes pulling 16kGCW to 31kGCW load weight for 9k miles of total mileage.

My 18k mile LT average 17.1mpg

After one learns to control the right foot top speed, I increased my fuel mileage by 15% with changing my old driving style.

Edit: I forgot to add the most important, all fuel mileage was calculated by total miles/total gallons used since day one with 18 miles on in a excell spread sheet. 99% of the fuel used is from the same pump and fuel stop.



[img]/forums/images/%%GRAEMLIN_URL%%/cool.gif[/img]

[MeanMrMustard]

Thanks for all the replies. I have also experienced better mileage at slower speeds. Really I was just wondering if these other drivers were right. Their theory is that the gooseneck does less tugging on the suspension. Therefore the load seemed to be more constant & the engine was not being loaded/ unloaded quite as much. I just couldn't believe it could make 1+mpg differnce as they told me. I guess I will just drive slower & have to stop less often for fuel to make up the difference. A bigger tank is in my near future. Thanks again.

[Copper]

They're kinda-sorta right about a gooseneck getting better mileage, but there's so many variables I don't know if you could really measure it. It's just like you say, it's a less "dynamic" load, as a goose doesn't try to sway and bob as much, as it doesn't have the leverage on the tow vehicle a bp does. I've never checked very scientifically, but I've access to two semi-comparable trailers, a 24' bp tilt-deck (work), and a 26' gooseneck tilt-deck (personal) that are of pretty similar construction with the same axles. SOTP, the goose pulls way straighter and smoother, and with similar loads (little tractors, pickups, etc.) the tow pickup runs along smoother with less gear hunting and corrective steering, etc. I'm convinced it's not anything aerodynamic, it's all in how nice it tracks. I suppose that can carry over to better mileage.....