Lets talk fuel economy and ways to improve.

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lakedawgs

lakedawgs

Active member
Joined
Sep 26, 2007
Posts
37
Location
Indiana
Hello,
I have a 1999 Dodge Ram 2500 4x4 5.9 gas engine with 4.10 gears. I am pulling a 25' TT, about 4500# loaded. My daily driver gets 30mpg. I'm not thinking I can get too close to 30mpg but want to know what things I can do to improve mileage. I know the biggest thing is to drive 55-60, thats easy, but what about things like a flow through tailgate, cold air intake any other ideas? What really works and what does not?
This truck will be used only to pull the TT (weekend camping 6-8 times a year for now), and odd jobs, it will see little mileage otherwise.
Any advice would be appreciated.
Lakedawgs
 
If you can, try staying in line with other RVers or behind a truck, drafting at a SAFE distance.  If I can't find some RVers I look for trucks from JB Hunt, Schneider, Swift or one of the larger freight lines. I find they tend to hold their speed at 65mph or a little less, which is where I like to be. I find this will bump my towing mpg from 10 to anywhere from 12 - 14. The only problem is, staring at the back of the same truck or RV for a few hundred miles can get real dull.
 
Don't know about these days, but years ago, when I was driving, that would really tick a truck driver off. When drafting, it's curteous to take the lead, now and then.

I haven't seen much drafting, in recent years. I know what it is and how to do it, but don't. And, if you are a "safe distance" back, there isn't much "draft," if any.

Ray D  ;D
 
That is interesting, I have heard that drafting is a myth unless you are within a couple of car lengths but have no personal experience with drafting myself. As my family will always be in the truck while pulling the TT I will have to rule out drafting as an option.
I don't mind spending a bit of money to gain a mile or two per gallon. Its pretty easy to figure how long it would take your to recoup your investment to determine the 'value' of the item.
THANKS,
Lakedawgs
 
Based upon your usage, you are just kidding yourself with the economy.  By not driving, you save money up front and then lose it, and then some, in depreciation of the vehicle just sitting.

In my case, I lose enough in depreciation that easily exceeds the cost of operation each year.  Best to sell it or rent instead if you're not going to use it.

 
I have heard that drafting is a myth unless you are within a couple of car lengths but have no personal experience with drafting myself.
Click to expand...

It's no myth. Back in the good ol' days, it was pretty common. A couple of car lengths is in the ball park. You can feel it when you "hook up." You can let up on the pedal, a little bit. You can also feel it when someone "hooks up" to you. You need a little more pedal. In the old convoy days, truckers would take turns with the lead. Lead truck (Front Door) buys the gas, so to speak, so after some distance, "lead" drops back and a new "lead" takes over. The guys in the middle (the rocking chair) get most of the benefit. Not much distance between trucks.

Ray D  ;D
 
Don't forget the proper maintance on your vehicle, tire pressure, alignment, tune-up, and I hear rumurs that racing stickers make it improve also.  ;D

Brian
 
Regarding the Magnum 5.9L engine, it tends to ping slightly under load when running on regular fuel.  I have never driven a 5.9L that didn't.  I've found that moving up to midgrade unleaded fuel when towing eliminates the pinging, provides a tiny boost in power (only noticeable when towing really) and a boost in fuel mileage that offsets the increase in fuel price.

We've tried everything to stop the pinging in regular fuel in my father's 2001 Ram but new intake seals, a computer re-flash, and a timing check later and the truck still does it.  Consequently, I've noticed that the new 5.7L Hemis recommend midgrade now.

 
The 5.9 is known for pinging, (also known as detonation) which can cause serious harm to your pistons,. If the re-flash didn't work, your only viable options are using a higher octane gasoline and/or changing to a lower temp thermostat - a 180 degree. Don't ignore the problem.
 
I bought a tin of compression for my truck and it works great and dont forget to keep the muffler bearings greased for the extra lubrication  :D
 
If you're close enough to a truck to draft, you're in his "No Zone" and he can't see you.  You had better have excellent reflexes to tailgate that close.  I much prefer the 3 second rule, my life is worth more than a few gallons of fuel.
 
I must agree with Ned.
To get any draft effect you have to travel too close to the truck,just back off a bit and you get buffeted with the turbulance,those bikers amonst us will know about that.The best thing i found to conserve gas or diesel is to set the cruise at 60mph instead of 65mph after all we are on vacvation and in no hurry,even with our ? to $ exchange rate i still feel the pinch on fuel prices
 
I agree about the drafting, while an interesting in concept, its a non-issue here, ain't gonna happen.
I'm surprised nobody has mentioned cold air intake experience or any other mods to increase gas mileage. I'm not thinking I can get an extra 5 miles per gallon but know there are things out there that can help.
If I currently get 13mpg and can do a mod to increase mileage to 14mpg, at $3.50 per gallon for gas I will save about .02 per mile driven. Every $100 of modification cost would take about 5000 miles driven to pay off and start seeing benefit. For you full timers it seems a proven mod would be a no brainer, but to someone like me who, 5000-7000 miles a year will be a stretch I really have to evaluate the value in the long run. And fuel prices are only going up.
Maybe there are no mods that really help. If its just keeping stock size tires, proper inflation, well tuned engine and keeping your speed smooth and under 60mph, those things are easy.
THANKS,
Lakedawgs
 
Ned said:
If you're close enough to a truck to draft, you're in his "No Zone" and he can't see you.  You had better have excellent reflexes to tailgate that close.  I much prefer the 3 second rule, my life is worth more than a few gallons of fuel.
Click to expand...

Well stated Ned and I agree completely.  Drafting is just not a good idea.
 
The problem with the touted modifications is the evidence for their working is anecdotal at best and never seems to have any rigorous testing under controlled conditions to support the claims.  Testimonials just aren't convincing :)  You stated the easiest ways to maximize your fuel economy, good maintenance, proper tire inflation, and a light foot.
 
I'm not aware of any practical or proven methods to reduce wind resistance.  But I sure would like to see something that works.  I notice about a 20% decrease in gas milage pulling into the wind versus no wind. I may get a 10% boost in gas milage with a tail wind. 

IIRC, the wind force acting on the front of the vehicle is a function of the square of the velocity of the vehicle in relation to the wind.  Thus slowing down when pulling into the wind should improve fuel milage to a greater extend than it does when just driveing slower in no wind conditions.
 
Drafting.   Drafting is what race car drivers do and it is done inches off the bumper of the lead car who usually is a teammate cooperating with the draft.   Race car drivers are superbly trained and conditioned crazy people helmeted and dressed in flame-resistant long johns and strapped inside roll cages at the wheel of state of the art vehicles with ultrafast steering, gum-ball racing tires replaced several times during a race, over sized 4-wheel disk brakes, and 600 horse engines.

RV drivers are generally out of condition, middle aged people in baseball caps, dressed in shorts.  wearing a light seat belt and harness inside of a tinny cab with sloppy power steering, on over-aged tires, with disk-drum brakes that probably need pad replacement,  and with over-stressed 200 HP engines.

There is a standard rule of the road that one should maintain a 2 second interval behind the leading vehicle.  That is 176 feet at 60 mph.

In my humble opinion, RV should keep a 3 second interval.  That is 264 feet at 60 mph.

Back 264 or even 176 feet there is no wind vacuum, there is merely turbulence.  Turbulence ain't a draft.
 
Improvements in charge air intake cooling might yield a few tenths of mpg. Modern diesels all have charge air coolers but the standard set up has to fit in many rigs and is thus generic.  I suspect that improvements are possible for specific installations. How cost effective it is for the average owner is another question.

It should also be possible to tune the coach aerodynamically, but actually knowing if you improved anything is hard without a wind tunnel. And would you take off awnings and add fairings to exterior ducts such as fridge or dryer vents??? I'm sure some would, but how many?

Everybody can slow down and watch their mpg figures to find the best performance spot for their rig. Takes no special skills, no engineering and costs no money.
 
I bought a tin of compression for my truck and it works great
Click to expand...
I certainly hope you remembered to install the cryo-hardened grunion rings before adding it. People have tried to 'cheap out' before and ended up replacing the whole lower crookshaft, balance beam and main oil galley fasteners as a result.

I'm surprised nobody has mentioned cold air intake experience or any other mods to increase gas mileage. I'm not thinking I can get an extra 5 miles per gallon but know there are things out there that can help.
Click to expand...
The only real advantage to a cold air/ram air system is to increase power. The computer senses the cooler air temp and/or the greater air density and adjusts the amount of gas accordingly; more -  not less. On a recent trip to Camping World, I saw the Banks version of the ram/cold air intake kit for around $400+!! Anyone with a little ingenuity and some 4" irrigation pipe and a couple Tupperware bowls could do the same thing for about $20. Oh, Sorry - The "Banks" decal is probably what makes up for the difference in price. ::)

 
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