Help me get better then 6 mpg please.
 

I recently started a new job that involves us driving all over the country. The catch is that the truck and trailer that the company gave us were never meant to be used together.

We have a 2005 Ford f150 lariat like this

https://www.classyauto.com/image342622.img

and a trailer roughly like this

https://www.mtairygolf.com/14%20foot%...h%20lights.JPG

Our trailer might be a little longer but basically like that. Im not sure how much it weighs but I would guess somewhere in the 7000lb range. The truck now cant pull it in overdrive and we are averaging between 6 and 8 mpg depending on the road.

What are the best areo mods we could do to the 2 things in order to increase economy? We cant do much to the truck now bc it is still under warrantee.


Thanks for any help.

Michael

You can boattail the trailer, or just edge it (if that's the way to describe it). My sig meta thread has a link to a PDF at NASA's website where they tested aerodynamic mods for big tractor trailer boxes, and found that an edge hanging off the back helps.

Edit: Here's the links:
https://www.nasa.gov/centers/dryden/p...ain_H-2283.pdf
https://permanent.access.gpo.gov/webs...00-01-2209.pdf
https://www.greencarcongress.com/2005...at_tail_d.html

Cool thanks. Ill have to read that soon. Dont think we can boattail bc there are doors on the back. But a hangover thing on the back could be possible.

I have read that vortex generators may or may not help mileage but will they always help stability? And would they be effective on the trailer since it is just square at the back? This trailer catches the wind like a sail and the truck doesnt weigh enough to keep it strait, same happens when trucks pass.

Thanks

Sounds like you need to put a cap on the back of the truck to help the air flow and transfer some weight to the truck bed as well. The air tabs probably would help the trailer since that is exactally what they are designed to do.

The bed has a tauno cover. The things we would do wouldnt be funded by the company, most likely, so for now I would like simple cheap ideas. I have thought about a partial grill block but I think we need to get all the heat out of the engine/tranny as possible.

How much would putting wheel skirts on the trailor help?

I think a Kammbak (sp?) on the trailer will be the best aero mod to do.

Whatever you do, make absolutely sure the transmission can get as much cooling as possible. There's nothing tougher on an automatic transmission than towing (well, maybe snowplowing), and no part more vulnerable to towing damage than the transmission. Increased cooling and frequent transmission fluid changes are what makes an automatic transmission survive difficulty.

I doubt if a grille block is a good idea when pulling. The minute aero improvement is less important than preventing overheating.

Airtabs are also a minute improvement at best.

Skirts are a minute improvement too. But if you have some free coroplast or other appropriate materials lying around and can make some that don't look clownish, might as well. I wouldn't do the truck though.

The cap is by far the best idea, along with xfering some weight to the truck. It's "tonneau" cover BTW.

Second best might be partial kamm back on the trailer, a.k.a. "Clarkson device" as in holycow's last link. They didn't invent that though, so I'd hesitate to name it after them.

A deeper airdam might help some.

It's going to have awful aero no matter what you do unless you get radical and you can't really do that on someone else's rig. So then what? Keep it under 55 mph. I've found that when doing heavy pulling with my F150, 50-54 mph seems to be optimal. It's a sweet spot, juuuuuust fast enough to get overdrive (if there's no uphill or headwind) and juuuuuust slow enough to keep it from downshifting for every little thing.

6 mpg?!? :eek: I can't freekin' believe that. My F150 is a '94 with the 5.0, and even when doing the aforementioned heavy pulling it gets about 12 mpg.

Don't forget the basics like tire pressure. I'm not recomending raising the tire pressure too high, maybe just 5 psi above recomended pressure. I'd also check the wheelbearings to make sure they rotate smoothly.

Don't forget your driving habits. Keep the throttle steady, use cruise control when possible. Try to avoid flooring the throttle and avoid hard braking. If you look ahead and anticipate changing traffic conditions you should be able to get on and off the gas and brake sooner, which saves gas.

Lipstick on a pig. From the pics, it looks like half of that trailer is sticking up in the wind, aerodynamic brick style. You need to smooth out the front of the trailer or bridge the gap between the truck cab and front of the trailer with a cap as JanGeo suggested.

My 2002 GMC 1500 with the 5.3 gets 10-12mpg towing my camper, which weighs 5600-6000 pounds, has more frontal area, and more protruberances (all kinds of stuff sticking out of the roof). That's regardless of flat land or mountains, highway or country driving, etc.

It may be necessary to raise the tire pressure a lot even if you're not worried about fuel economy. Get on a scale and check axle weights, then compare to load-inflation charts. If it's even close, pump them up...leave yourself a lot of room. Tires failing from underinflation while towing can be a huge disaster.

Look into a trailer nose cone, too. While not cheap, they are not that expensive, either. The bonus is they are very lightweight. I believe Wells Cargo brand trailers sources their optional nose cones from these guys: https://www.nosecone.com/ .

Nose Cone has fitments for all sorts of different sized trailers including cargo trailers like yours. I looked into them once for my former trailer but decided that I didn't pull it often enough to make it cost effective for me.

Also don't even think about towing a trailer that heavy in overdrive. The transmission will hunt gears and rapidly overheat. Plus you probably won't be in the powerband and that will hurt your economy, too.

Bob

I wonder if lowering the truck would help - get more of the truck into the air flow of the low trailer. Definately need to check the trailer tires air pressure and maybe an alignment check and brake drag - check for things getting hot when just going on level road at a steady speed - this would indicate drag and friction - tire and rim / brake temps is a good indicator of something not right.

Check what lube you are using in the engine and gear boxes in the truck at the next service - upgrade there could save a lot of gas.

In the process of talking the owner into putting the biggest tranny cooler we can find on it. It has already had one transmission in it under warranty.

Yeah I knew it was wrong. I cant spell anything. I think I will look into trying to get some of the weight into the back of the truck, but it is already pretty full of stuff like our luggage.

Its a 5.4 and only gets 16 without the trailer. When I drive I try to keep it a little slower but the people I am with get antsy if I go much less then 65 on the interstate. I have tried to tell them that we only save like 5-10 min over the entire drive going faster. I have also noticed that drafting helps a little too.

Yeah but all they gave me was this Ford. I think that this 5 speed pos automatic tranny might have something to do with it or maybe that it is turning around 3.5k on the highway bc it wont pull it in overdrive.

And who knows it could weigh a lot more. I just guessed around 7000lb bc when it is behind the company f350 you can hardly notice it. We have never had it on the scales, I think that next time we stop at a truck stop ill get our rig weighed.

Its already got load range d tires. Ill check to make sure that the pressure is close to the max on them today.

I think ill try to come up with something to attach to the back of the trailer that could be easily removed for rear door access.

Thanks for the suggestions.

Michael

I think in addition to the tire pressures if you could convince the company to change the tonneau cover to a smooth canopy you will see an increase in towing milage. The gap created when the trailer is behind makes a big hole for turbulence to form. less of a gap less drag.

Are the tires bias ply or steel belted radials?
At one of the last company's I worked for we had a similar trailer with a single axle. We always had it loaded heavy, and kept burning through the bias ply tires. We had radial tires installed and it solved that problem. My thought is the radials would have less rolling resistance because the inner part of the tread contact patch isn't caving in.

Dont know, Ill check it out.

Do you guys think that a shell could help much? The trailer sticks up quite a bit more then the back of the truck does. A shell could be nice though for more storage in the truck. That could help convince the owner, or if anyone has data on mileage gain from adding a shell.

Jetta90GL Is that your truck in your avatar? How much did you gain from the extended air dam?

Thanks

:eek: That's a lot of RPM for that gear. I guess that could be the problem. You would think that with an extra gear it could run closer to the most appropriate ratio. In my truck, 70 in 3rd (1:1) is 2900, or 2000 in overdrive (.7:1).

Remember, load range just means maximum pressure; for a given size, a load range D tire at 44psi is rated for the same load as a P-series or LT-series standard load tire...load range D is good for 65psi.

I run 80psi in load range E tires, except when empty I run the rears closer to 70psi.

I think so.

You would think but it doesnt make enough power to pull it in overdrive, unless we are going down hill. And 3500 might be a little high more like 3200 at 70.

I just hope that the other crew is done with the big truck soon so we can use it instead.

Thanks

I wouldn't expect it to pull that in overdrive. 3200 sounds reasonable for 70 while towing...3500 would be too much IMO.

Cat's out of the bag- they're speeding too much in it for decent mileage. I'm sure if I went 65 my fe would drop to single digits too.

OK how far are your trips? The trip times at different speeds are easily calculated. I too had antsy passengers when I drove on a 60 mile trip at 55mph:

60m @ 55mph = 1.09 hours, or 1 hr 5 min
60m @ 65mph = .92 hours, or 55 min

Woo Hoo, 10 minutes savings. We always screwed around more than 10 minutes prior to leaving, and screwed around more than 10 minutes after getting there, so IMHO that 10 min "penalty" is nothing. If it's that important, leave 10 min earlier.

Any chance of going Diesel?

-BC

anywhere from about an hour and a half to 22+ hours. We are leaving from the middle of Missouri to go to Phoenix Arizona in a few days. Then either to Denver or somewhere in Pennsylvania.

The company has a different truck that is a Diesel that hopefully we will be able to use in the near future. I was just going to see if anyone could come up with some neat ideas. The company doesnt care what the fuel bill is I just like to see if I can improve my fe.

If we could improve 1 mpg with some areo mods we could save around 40 gallons of fuel. And if we could somehow average 10 mpg then we would save close to 100 gallons of gas.

Maybe I should bring that up with the owner.

**edit**

Going 65 we can shave around 3.5 hours off of our next trip. The speed limit is 70 so its not like we are speeding too much, I guess what we really need is a truck that will actually pull the trailer.

I doesn't matter what I'm on- motorcycle, car, truck, truck and load... mileage ALWAYS drops precipitously above 60 mph. Unless you have a radical teardrop car like basjoos, that's how it is for the rest of us.

The important issue when it comes to speed is trailering safely. 70 is pushing it in a rig like that.

You really should get the trailer and whole rig weighed, compare it to the truck's tow rating and GCWR, and make sure you've got lots of extra. If the whole thing wipes out because the tail wagged the dog, it's your driving record on the line, and your life on the line.

Yeah do a 40mph stopping distance test and see how that compares to conventional stopping distances you may find that it takes more than 100 feet at 40mph to stop and that translates to 50-60 mph stopping distances for cars - you need to slow down or you will ram someone trying to stop quickly. Use that as a safety reason for driving slower.

We have got trailer brakes. But I can see where you guys are coming from.

Safety first.

Safety isn't only about braking; and trailer brakes are only supplemental.

Sway, crashes, emergency situations, etc all get more dangerous when the tail is heavier than the dog. If your brake controller has a manual braking button, you can correct minor sway by using it but if you get sway every day you need to change your rig. If you don't get sway that doesn't mean your rig is safe.

Safety schmafety. Just go slower.

Think of all the time you'd save not stopping to refuel! :)

You think hitting that immovable object hurts then the trailer comes up and hits you in the ask me no more questions even if you try. Yeah Safety is a good thing. Reminds me of New Years Eve last year coming up a hill and turning into a side street . . . in the snow and ice . . . couldn't stop . . . couldn't turn . . . heading for the corner of a stone wall . . . finally stopped 2 feet from it and had to back up to make the turn.

Tell them to give you the diesel. I don't know the towing capacities off hand but 7000LB seems like on the high end for an F150.

I've got a 7x14 tandem axle box trailer myself. My previous towing vehicle was a GMC Yukon. When fully loaded (8000+lb) I averaged 9-10 MPG and had absolutely no power to climb hills. I recently picked up a GMC 3500 1ton Diesel Van. Not only does it pull the fully loaded trailer like a dream but I averaged 16.5mpg on my last 400mi round trip. Normally I average 17.5-18.5mpg unloaded in that van.