Gas mileage ?

[pchast]

Adirondackersouth

If your new TD is (smaller) within the shadow of your SUV you are
unlikely to see much difference in the gas mileage. With my '15 Frontier,
4cyl 2wd, I get 19 at 70mph unloaded. When I add the TD, with no cap to
streamline things, I get almost 16 at 70mph. That s about 20% cost. For
comparison its about 30% drop when using my wife's VW with a smaller
turbo engine and a TD a foot higher than the car top.

[Adirondackersouth]

on my ford explore on a 800 mile trip to rifle colorado and back to pavillon, wyoming I noticed no drop at all in gas milage towing my teardrop.

No lack of power and I towed 65 mph even up hills. I out ran larger motor homes and bumper pull rvs. same rigs known on here as ttt or standys.

I ran with no sway problems 65 in hard wind in wyoming and down around rifle last labor day.

I out ran my buddy towing a large boat with the same explore his is a 94 mine is a 95.

I make this trip to colorado every labor day and I go almost every year.

I have driven it with the same 95 ford explore about 5 to 6 times.

I got the same gas milage towing my teardrop last year as I got with out it the years before.

Slowcowboy.

Hey Slowcowboy -

The debate in my head and the conversations I have had since exploring the whole concept of long haul teardrop travel has me feeling a bit vexed on several levels.

For starters I have a Toyota Highlander with 143K. I have ordered a hitch and ball that should be in soon. I can, or I think I can install it myself according to those who do these kinds of things and of course YouTube is a good instructor of many things. So once that is done, the next challenge is should I beef up the cooler and brakes or leave well enough alone. My goal is not to haul cattle or cement in my trailer of choice, and where I will be traveling it will be a lot of stop and go traffic for a good stretch then highway then back to start and stop. Some off road and some extended camping or bunking with friends and relatives maybe. I am not the guy currently to hit the high passes of the West, but there may come a day when I start heading West, so your encouragement does give me hope. I had a 2000 Ranger XLT that would have hauled with impunity, the SUV I now have is rated at 2K, not 4K as was the truck. I get 24 mpg unloaded and about 24 mpg loaded with camping, fishing gear with two boats on the roof. One kayak and one old canoe rides on top with a combined weight of 160 lbs. Again the Highlander did very well last summer when I tripped North. Adding a trailer of 1000 lbs is substantial wight but not bad enough to worry too much. Again that is why my attention has been focused on Teardrops.

The other big question is finding one in my price range which has been a challenge and a half. But I think I can do it before June. I hope anyway.

Any suggestions? Know anyone in the Richmond, Virginia area that has one to sell?

Cheers

[Redneck Teepee]

My experience with fuel mileage while towing my teardrop has always been a wash or increase. Its well known that when you start pushing above 55 mph your mileage starts to take a hit, when not towing I'll push to 70 mph more often than not on the highways.
The speed limit in Kalifornia for towing is 55mph and I pretty much stick to the speed limit. I set it on cruise control 55-58 mph depending on traffic flow, when your on teardrop time you should not be in a hurry anyway.
I tow with both a V8 gas hot rod pickup, and a Duramax diesel pickup which I know also makes a big difference in available power/torque. Weighing in at about 1400 lbs neither one knows it's even behind it.
Cruise control and 55 mph are your best friends, it keeps the CHP busy with other people and improves mileage.

[JaggedEdges]

I have some experience with fluid dynamics also, and think it's likely that in some instances a low in height well formed teardrop could improve the overall aerodynamics of the combination. From skimming through, I'd give a kind of spitball of if your coefficient of drag is no less than about 0.4, your frontal area is no greater and the trailer is lower than the aerodynamically significant trailing edge of your vehicle, then you might have same mileage or even gain a tad. By a.s.t.e I mean where the bulk of the air departs the vehicle, for older trucks that may be the top of the cab, whereas with newer trucks it could be the top of the tailgate. For slippier sedans it would be rear edge of the trunk, but for some it might be at the roofline.

However, infernal combustion engines are stranger devices than most imagine, nothing is linear. Completely counter-intuitive is that your engine is not necessarily the most efficient at the speed where you get the best mpg, maybe for small 4 cyls, not so much for anything else. This is because efficiency, which is consumption per horsepower actually produced, and usually quoted technically as pounds of fuel per horsepower x hour, varies with load as well as engine speed. This is known as Brake Specific Fuel Consumption, if quoted as single figure it is peak value and not necessarily anywhere near peak output or peak torque.. https://en.wikipedia.org/wiki/Brake_spe ... onsumption

Now then, this can mean that a lightly loaded engine, like a big one, not pulling much, can be in a bad area for BSFC, only 30HP may be required to bowl it down the road, but maybe at this RPM and only 15% of it's rated output, it's sucking a particularly inefficient 0.6 pounds per HP x hour. Now if we place a higher demand on it 40HP, by dragging something, at the same speed, it might move into a more favorable area of the BSFC map, and only demand 0.45 pounds per HP x hour. So what is the fuel consumption per hour in the first and second case? Both identical, 18 pounds an hour, sorcery you say, no a direct consequence of the laws of thermodynamics as applied to internal combustion engines.

In the case of a smaller engine, it might already be near the best BSFC efficiency, it's more highly loaded, say 30% to produce the same output, now we might presume that in an "economy" car, the manufacturers have arranged this very thing, that at typical highway speeds it's in a good area on the BSFC map, by the design, valve timing and all other factors, with another passenger or two it might not change much, however, double it's load, by making it move twice as much, and it might scoot right over that good area of it's BSFC map and off the other side, resulting in higher specific fuel consumption per horsepower and getting very bad gas mileage overall.

However, this all jumps back to the aerodynamics again, the less change there is in that, the less change in load, with some outlier situations with lightly loaded large engines that there is wriggle room in the science to actually gain mpg with worse aero, and also lose mpg with better aero.

Weight tends to affect overall mpg less the longer your highway cruise is, because rolling resistance is most significant at lower speeds, and for of course, accelerating to higher speeds. At highways speeds it's dropped in significance to a few percent of total load. If total aero drag remained constant, the difference in load from weight and hence rolling resistance at speed between a regular car, and towing something half it's weight on another set of wheels, would typically be similar to having the A/C on or off.

[Adirondackersouth]

I have some experience with fluid dynamics also, and think it's likely that in some instances a low in height well formed teardrop could improve the overall aerodynamics of the combination. From skimming through, I'd give a kind of spitball of if your coefficient of drag is no less than about 0.4, your frontal area is no greater and the trailer is lower than the aerodynamically significant trailing edge of your vehicle, then you might have same mileage or even gain a tad. By a.s.t.e I mean where the bulk of the air departs the vehicle, for older trucks that may be the top of the cab, whereas with newer trucks it could be the top of the tailgate. For slippier sedans it would be rear edge of the trunk, but for some it might be at the roofline.

However, infernal combustion engines are stranger devices than most imagine, nothing is linear. Completely counter-intuitive is that your engine is not necessarily the most efficient at the speed where you get the best mpg, maybe for small 4 cyls, not so much for anything else. This is because efficiency, which is consumption per horsepower actually produced, and usually quoted technically as pounds of fuel per horsepower x hour, varies with load as well as engine speed. This is known as Brake Specific Fuel Consumption, if quoted as single figure it is peak value and not necessarily anywhere near peak output or peak torque.. https://en.wikipedia.org/wiki/Brake_spe ... onsumption

Now then, this can mean that a lightly loaded engine, like a big one, not pulling much, can be in a bad area for BSFC, only 30HP may be required to bowl it down the road, but maybe at this RPM and only 15% of it's rated output, it's sucking a particularly inefficient 0.6 pounds per HP x hour. Now if we place a higher demand on it 40HP, by dragging something, at the same speed, it might move into a more favorable area of the BSFC map, and only demand 0.45 pounds per HP x hour. So what is the fuel consumption per hour in the first and second case? Both identical, 18 pounds an hour, sorcery you say, no a direct consequence of the laws of thermodynamics as applied to internal combustion engines.

In the case of a smaller engine, it might already be near the best BSFC efficiency, it's more highly loaded, say 30% to produce the same output, now we might presume that in an "economy" car, the manufacturers have arranged this very thing, that at typical highway speeds it's in a good area on the BSFC map, by the design, valve timing and all other factors, with another passenger or two it might not change much, however, double it's load, by making it move twice as much, and it might scoot right over that good area of it's BSFC map and off the other side, resulting in higher specific fuel consumption per horsepower and getting very bad gas mileage overall.

However, this all jumps back to the aerodynamics again, the less change there is in that, the less change in load, with some outlier situations with lightly loaded large engines that there is wriggle room in the science to actually gain mpg with worse aero, and also lose mpg with better aero.

Weight tends to affect overall mpg less the longer your highway cruise is, because rolling resistance is most significant at lower speeds, and for of course, accelerating to higher speeds. At highways speeds it's dropped in significance to a few percent of total load. If total aero drag remained constant, the difference in load from weight and hence rolling resistance at speed between a regular car, and towing something half it's weight on another set of wheels, would typically be similar to having the A/C on or off.

Hello Jag,
I appreciate the science behind the evidence. I wonder if my Highlander is at optimum BSFC?

[JaggedEdges]

I wonder if my Highlander is at optimum BSFC?

If you have the 6 cylinder 2GR-FE engine, there was some discussion "around" it at the Tacoma forum, with this BSFC map..


Gets interesting from post 109, NSFW warning for language here though... https://www.tacomaworld.com/threads/201 ... 512/page-6

Not sure you have the same gearing, but you could compare your final drive ratios and mentally interpolate.

EDIT: BTW the 2GR-FE is in bold over the top, think the intent of the image was to show how they made the hybrid engine better, the numbers refer to that one, more detail in that thread.

[noseoil]

Average with a Nissan Frontier (2007, 2.5L 4 cylinder, 5 speed manual) with the trailer is 20.5 mpg. Worse if in the mountains & pulling on long grades.

[haha49]

the weight issue has been bouncing around in my head lately, more so as i read more about mike's giant foamy. i'm trying to shave lbs off my 4x10 woody to ease strain on my car climbing mountain roads. i'm only at 1100lbs fully loaded, but think how much better the mileage and performance if i could have another 2-300 lbs lighter...

Not much. It's drag ie height and width that will kill mileage. Make it skinny like a cigar tube then you will see better results. Think like moving through water put the wood length wise it slips through go width wise it's hard to push. Width and height equals more drag

[gudmund]

2007 Chev Colorado 3.7litre 5cyl Auto w/cab level canopy towing 4x8 1200 lb Tear 13000 miles so far = 18.1 mpg average - without the trailer, 6000 miles average about 18.5 mpg - about 18.3 mpg overall since owning it. Sometime on a level freeway run I may see 21/22 mpg w/Trailer or not. Back roads up and down about 17 to 19 with or out. The trailer for the most part is in the shadow of the truck - no bigger no less, has a nice even level height with the truck and canopy. This truck has twice the power and torque of the "base" model 2000 S-10 2.2litre 4cyl-5sp I was using before which did alright, all things considered. It would get 25/29 mpg without the trailer and 22/24 mpg with the trailer but you definitely knew you were towing a trailer being it felt like it was tugging something, used to just look for a semi to hide behind and sit it out. Would probably be getting better MPG with the Colorado if I was still practicing the S-10 style of driving but with the power difference, it is just so much easier to cruse on by and do the speed limit.

[noseoil]

Quick update with the 4 cylinder Nissan Frontier. Had to follow a maniac with a Mini towing at 75 mph last weekend, 17.5 mpg on the outbound leg. On the way home did the usual 65-70 & mileage went back up to 20.5 again.

[Originalspacerob]

Stumbled across this thread by accident. Great info on the vehicles.
My current tow vehicle is a 2011 Subaru Forester 5sp manual. I get 23-24mpg mixed driving and 20-21mpg towing a 1300 lb. teardrop with mixed driving. The teardrop is about 8" taller than tje forester and its track and width is the same.
Next week will be our first long highway drive with it thru upstate New York so I will update once we see how the highway does thru the mountains.

UPDATE:
We did our first real camping trip with the teardrop 2 weeks ago to Lockport NY. The highway drive up was a combination of flats and hills. We were mostly climbing on the way there. The car averaged 18-19 mpg with the two of us, our springer spaniel and the fully loaded teardrop. About 1600 lbs on the trailer. On the way home we did average 20 mpg for a short period of time. It towed just fine and only a few times did i have to downshift from 5th gear going up larger hill. The speed ranged from 60-70 mph, but mostly tried to stay at 65.

[noseoil]

On the recent 4,100 miles the average was 20.26 mpg, towing with the 4 cylinder Nissan Frontier.

[yrock87]

Not trying to discourgage the conversation because that is what forums like this are for. but my thought on the MPG question is, "does it matter what your MPG is towing your TD"? I would venture that really the answer is no. who cares if it costs you an extra $2 in gas over your 300 mile weekend trip? who cares if it costs an extra $10? it is easier and cheaper than buying a new car to tow a full size TT or 5th wheel.

My dad bought a brand new mustang a few years back. he had been waiting for 20 years to replace the Maverick he sold when I was born. showing off the car to his coworkers the first day he drove it. somebody asked "what kind of millage does it get" his answer was " I don't know, I don't care. It puts a smile on my face."

I imagine that most feel the same way the first time they drag their TD with their daily driver, to camping spots that 40ft 5th wheels would never be able to venture.

[pchast]

You are quite right.

Its also interesting to note the effect of different tow setups
and the numbers resulting too.

[lrrowe]

I do not let the gas cost affect my decision to travel. Especially at today's under $2 cost per gallon. But it is good to know so if you have choice of vehicles, choice of route or other similar conditions, you can make a decision based on cost. We keep track of our cost to build do we not?
We also many times use cost criterias for choosing one material or technique over another.
So I see it as just a part of the overall process/experience.

Now, would we be saying the same at $5 per gallon or for sure with gas rationing. For those old enough to remember the 70's will relate to that.