Towing & Trailer Aerodynamics

[GQ-01]

I started a home business last year and I use my '02 Sierra as a work truck. Much of my daily driving is at highway speed (60+ mph), and I'm in the market for an enclosed trailer. I am interested if anyone has experience in the following areas as it pertains to towing:

 

1. Open bed vs. tonneau cover vs. camper shell*
2. OEM Tailgate spoiler (I believe stock on '03+ year models)
3. V-Nose trailer vs. nose cone**

Here are the facts of my truck:

• 2002 GMC Sierra 1500, extended cab, 6'6" fleetside bed
• OEM suspension & wheels
• RWD, OEM gear ratios

Also, does anyone know of any aftermarket aerodynamic packages for small trailers like ATDynamic offers for 18-wheelers?

 

*Towing a 7'-tall trailer

**I intend to buy a 7'x12' v-nose trailer for the extra real estate, but I'm interested in the aerodynamic differences and advantages.

[BlackZ71Silverado]

The best aero. for your truck it without the bed covered at all. All covers disturb the factory aero. design. No matter what yo uadd, your MPG's are going to suffer towing.

[r1byker]

I can't answer your specific questions but I can tell you what my experience has been making the 400 mile drive between the San Francisco Bay Area and Southern California.

 

Driving 70 mph without a trailer, I get 20 mpg with my Duramax. That's with a Leer cap.

 

When I tow my Wells Cargo 6 x 12 box trailer with a 6' interior height and flat nose, I get 14.5 mpg. That's if it's empty. When it's loaded with several thousand pounds, it drops to about 13 or 13.5.

 

About a month ago, I towed a car down. It was an old Toyota Celica; probably weighs around 2,500 lbs. I used one of those dollies from U-Haul that carries the front wheels so there was no aerodynamic drag. Much to my surprise, I got 18 mpg running at 65 mph. (California has a split speed limit; trucks and vehicles towing are limited to 55 mph.) The difference in mileage between my box trailer and towing that car give an indicating of how much is lost due to drag.

 

The v-front will get you better mpg than a bubble front; I don't think a bubble front will make a huge difference. That's why I didn't have one installed on my trailer. (They must make some difference, though. They were installed on our older trailers at work.) IMHO, a cap would help with improving mileage because there would be a smooth airflow from the truck and cap to the trailer.

 

Are you talking about the trailer tail assembly from ATDynamics? I haven't seen anything for small trailers. They seem like too much trouble. Keep in mind that that big rigs are running full-time and put on 100,000 miles a year or more. Unless you're doing nothing but towing a trailer in your business, I don't think there will be much of a payback.

[GQ-01]

The difference in mileage between my box trailer and towing that car give an indicating of how much is lost due to drag.

 

The v-front will get you better mpg than a bubble front; I don't think a bubble front will make a huge difference. That's why I didn't have one installed on my trailer. (They must make some difference, though. They were installed on our older trailers at work.) IMHO, a cap would help with improving mileage because there would be a smooth airflow from the truck and cap to the trailer.

I don't doubt your economy suffers greatly from a box trailer. The negative air pressure created behind the trailer actually sucks it rearward. Also, it's worth checking out

showing the areo effects of a nosecone/bubble on a box. While the video doesn't tell us air speed (nor does it have a tow vehicle), I presume the test was done with the same velocity. You can see the air affecting streamers on the side of the box and the sucking effect on a box trailer. It's not just air pushing the front of the trailer like you might think. I'd be curious to see if your economy improves without the camper shell. By your numbers, your economy suffers anywhere from 30-40% depending on trailer weight. I don't have a gnarly 6.6L diesel, either (I wish). I got an old 5.3L gas engine that doesn't have near the torque numbers you've got. By your fuel economy, I doesn't seem to me like that camper is helping your aerodynamics (in my amateur opinion), like Justin is saying. I was thinking that a camper at the same height as the trailer might help. Perhaps the trailer is too far back for that to be the case.

 

Are you talking about the trailer tail assembly from ATDynamics? I haven't seen anything for small trailers. They seem like too much trouble. Keep in mind that that big rigs are running full-time and put on 100,000 miles a year or more. Unless you're doing nothing but towing a trailer in your business, I don't think there will be much of a payback.

I work out of my truck, and once I have a trailer, it means I won't have to load and unload heavy equipment and tool boxes out of my bed anymore, so I will be towing full time. I just sent ATDynamics a contact request, so I'll let y'all know what they say.

 

The best aero. for your truck it without the bed covered at all. All covers disturb the factory aero. design. No matter what yo uadd, your MPG's are going to suffer towing.

I hear you, and I think probably just about everyone has seen that Myth Busters episode showing tailgate up vs down for fuel economy effect. I've had my pickup for over a decade and have resisted putting anything over the bed. However lately, there have been more and occasions where I would prefer the ability to lock the contents in my bed, especially with the home business. I think it's also interesting that NASCAR trucks to have an enclosed bed. I wonder at what air speed does that become beneficial.

[GQ-01]

 

is a four-part aerodynamics crash course on Volvo trucks. Interestingly, part 3 talks about trailer gap, which I had never thought of before we opened this dialogue.