RV.Net Open Roads Forum: General RVing Issues: Identifing Fuel Economy factors

RV Blog

  |  

RV Sales

  |  

Campgrounds

  |  

RV Parks

  |  

RV Club

  |  

RV Buyers Guide

  |  

Roadside Assistance

  |  

Extended Service Plan

  |  

RV Travel Assistance

  |  

RV Credit Card

  |  

RV Loans

Open Roads Forum Already a member? Login here.   If not, Register Today!  |  Help

Newest  |  Active  |  Popular  |  RVing FAQ Forum Rules  |  Forum Help and Support  |  Contact

Search:   Advanced Search

Search only in General RVing Issues

Open Roads Forum  >  General RVing Issues

 > Identifing Fuel Economy factors

This Topic Is Closed  |  Print Topic  |  Post New Topic  | 
Page of 3  
Prev  |  Next
Sponsored By:
hone eagle

essex ontario canada

Senior Member

Joined: 11/18/2004

View Profile


Offline
Posted: 02/22/12 05:10pm Link  |  Print  |  Notify Moderator

the act of starting the engine is the beginng of mileage going downhill :-)





sorry couldn't help myself


2005 Volvo 670 singled freedomline 12 speed
Newmar 34rsks 2008
Hensley trailersaver TSLB2H
maxbrake controller

-when overkill is cheaper-

K3WE

Missouri

Senior Member

Joined: 05/24/2005

View Profile


Offline
Posted: 02/22/12 05:55pm Link  |  Print  |  Notify Moderator

hone eagle wrote:

the act of starting the engine is the beginng of mileage going downhill :-)


sorry couldn't help myself


The OP has a Nice long list, he forgot to list "the trailer"

(Could not help myself with that either)

It's fun to discuss all of this, but starting the engine and hooking up the trailer have a huge effect on mileage. All the other stuff is hair splitting.

C-172-AV8R

Duncan B.C. Canada

Senior Member

Joined: 11/10/2003

View Profile



Good Sam RV Club Member

Offline
Posted: 02/23/12 10:04am Link  |  Print  |  Notify Moderator

hone eagle wrote:

the act of starting the engine is the beginng of mileage going downhill :-)





sorry couldn't help myself
Another..."What's the worst thing you can do to an engine? Start it."


Pacific Islanders
Abby's Doghouse... 31'Winnibago Chieftain
Casara pilot
FMCA F371731
"Any Day you wake up is a good one"
Mike/Ulla/Abby


Nomadac

Columbus, IN

Senior Member

Joined: 11/22/2004

View Profile



Good Sam RV Club Member

Offline
Posted: 02/23/12 10:36am Link  |  Print  |  Notify Moderator

chevor wrote:

Do you know there are 18wheelers that pull 80,000 pounds and still get above 8mpg
How do you think thats possible?
THERE IS ALWAYS SOMETHING TO IMPROVE ON


Individual drivers have a greater impact on fuel mileage with any vehicle IMO. I used to do fuel mileage tests with owners in their vehicles using a 1/10 gallon tester and could vary the fuel mileage from 8-20+ mpg back in the mid 70's, just by driving habits, speed, acceleration, traffic, number of stops, etc. How the driver operates the accelerator/gas pedal and speed has the most effect.
With the owner in the back seat and the Service Mgr. working the tester, the owner would usually comment I don't drive like you are doing, which I would reply that is the cause for your poor fuel mileage, but does prove what fuel mileage for this vehicle is capable of achieving.

Same for an RV


Arnie
2003 Travel Supreme MH
38KSO1 Cummins ISC 350HP
2004 Honda Pilot w/SMI Air Force One Brake Sys.
1963 Pontiac Grand Prix 20' Enclosed Car Trailer

gmcsmoke

Butler

Senior Member

Joined: 07/13/2008

View Profile



Good Sam RV Club Member

Offline
Posted: 02/23/12 04:42am Link  |  Print  |  Notify Moderator

chevor wrote:

Im gonna start a list of things I think effect fuel economy of a vehicle pulling a trailer

Speed of vehicle
Wind- direction and speed
Aerodynamics of vehicles
Grade-Uphill or downhill
Tow vehicle tires- air pressure, tread type, size, rolling resistance, stability
Trailer tires- air pressure, tread type, size, rolling resistance, stability
Road Surface
Tempature
Weather-dry,wet roads, rain, snow
Time of day- sunlite, night
Engine- oil, air flow
Driver- Throttle use, acelerating, deacelerating
Hitch- stability, solidness
Suspension- stability
Weight- on each axel



Congratulations on making a list.

FunnyCamper

Southeastern

Senior Member

Joined: 09/29/2011

View Profile



Posted: 02/23/12 12:39pm Link  |  Print  |  Notify Moderator

Fizz wrote:

First and foremost it's SPEED.
After that it's all nickel & dime.
If you start worrying about the pennies, might as well park it.


X2


if you take it too far, you took all the enjoyment out of traveling with your rv.


in general...I don't worry the mircro details anymore except using common sense to try to get good mileage etc.

Slowmover

Corpus Christi, Texas

Senior Member

Joined: 11/14/2003

View Profile


Offline
Posted: 02/24/12 09:44am Link  |  Print  |  Notify Moderator

Some time with how to understand the factors of FE can pay off. Even subsidize the fuel portion of vacation expenses. Start from scratch and throw out old or incorrect assumptions.

The order of importance for mpg is this:

- vehicle specification
- climate
- terrain
- vehicle use

The relative order of importance for a vehicle pair is:

* Drivetrain Efficiency
* Aerodynamic Drag
* Weight
* Rolling Efficiency

Drivetrain Efficiency: Turbodiesel is top of the list for a properly spec'd TV.

Aerodynamic Drag: is *always* a *total* loss. It is about 50% of the total load at about 30-35mph, and it is 75% of the load at >65mph. (Not weight, not size, etc).

Weight: lower is better, but relevant only to starts/stops and elevation changes in comparison to aero.

Then, as to rolling efficiency, the best is:

* 2WD
* Manual trans
* SRW
* Rack & pinion steering
* Closed shoulder highway rib tires

The worst is:

* 4WD
* Auto trans
* DRW
* Recirc ball steering
* Open shoulder traction tires

Truck spec:

A bed cover (tonneau) is a proven help, and no bed topper should be outside of body lines (search also under AEROLID). WDH, dialled in correctly, should be a help in reducing the number of steering corrections per 10-miles (statistically significant), and anti-sway adding to this per design. No brake drag, no steering wander, book maintenance, tire pressure according to load, etc.

Trailer spec:

As for the trailer, aerodynamic trumps weight via 20% reduced horsepower demand, and is more resistant to crosswinds (steering wander). Radiused edges (all of them), low ground clearance, preferably torsion arm suspension. Tire pressure to sidewall maximum.

Climate:

Hot is always best for mpg. An almost linear relationship (1C drop = 1% loss).

Terrain:

Obviously, flat is best.

Vehicle use:

A vehicle not optimized for maximum mpg (and lowest operating costs) in it's major role (commuter, contractor) is badly chosen where RV duty is secondary.

55-mph always trumps 65-mph. (I use 58-mph).

The insistence on "too much truck" (even having a truck where another vehicle is better), 4WD where rarely used, etc, all contribute to higher costs without redeeming or offsetting performance.

To reduce vehicle expense: drive fewer miles performing the same work (trip plan; combine errands; no short trips), reduce warm-up times (pre-heat, year-round), keep on top of scheduled maintenance, etc. Run at least 10 under on the highway and 5-under around town. And only accelerate to 5-mph below those numbers. Then drift up. Never stop, and never idle.

For both vehicles the pair that lasts the longest are the cheapest. My folks had but one TT and two TV's over 27-years. 8-mpg is meaningless when that is understood properly.

The only mpg number that matters is average mpg computed quarterly or annually. Break it out for type, but in the end this is what the cost is: the average. All miles and all gallons figured. Occasional highs and lows are meaningless (and subject to manipulation). A gain of "2-mpg" is also a meaningless statement, as only percentage increases to the average mpg are relevant (can be supported).

Vehicle costs, understood as a cpm calculation (cents-per-mile) reveals what matters most, and that is depreciation and finance charges, etc. Fixed costs.

Without an overall view as provided by understanding cpm then the "dumb Amerikun" comes into play: my "cost" is my pair of monthly finance notes and fuel . . boy, talk about iggernant.

If fuel cost is the limiting factor for travel, then the original "plan" was no plan at all. Best to start from scratch and find the most economical rig from the get-go.

I calculate, conservatively, that my fuel cost while solo is 16-cpm (14-cpm actual last 37k miles), and that towing is 26-cpm (24-26 cpm actual). This translates as 4-gls/100-miles and 6.5-gls/100-miles. Or, at todays price ($3.8/gl diesel) it equals $15.25 and $25 per 100-miles of travel under best conditions (warm to cool temps, relatively flat terrain).

And if I want to cover the fuel cost of a 600-mile vacation, (towing @ $150), then the manner in which I drive while solo can more than cover this low cost over the rest of the year.

Similarly, with the TT then the break-out is on a per-night cost of use (all monies , over the life of the vehicle).

Properly chosen TT and TV are the place to start:

* How long will it (TT & TV) be kept/owned?
* How many miles (nights) over that time?
* Fixed costs aside, what is the "trip cost" average?

We'll find that folks fade away, making excuses about no longer being able to travel within their means. A better set of tools (cpm) and the discipline to make the gallons count (all year) could keep some of them on the road.

There was nothing magical about finding the highest mpg TV and the longest lasting TT in my case. The order of importance is: longevity, reliability and economy. Longest life at lowest cost with highest reliability.

On the TV: 22-mpg annual average the past 37k miles (got more serious about FE). 15+ while towing is consistent with more than a half-dozen others with CTD Dodges and aero aluminum trailers of from 28-35'. Both were good choices to start with (and paid just under $30k together), and sweating the details after that to establish best habits/practices gives me those mpg numbers. (As I am now a full-timer my per-night cost isn't quite relevant unless compared to others doing the same in the same way).

Reducing miles traveled and "wear & tear" just transfers the value to the next owner. And runs actual costs of use far higher over the period of ownership. Out-of-pocket expenses are the tip of the iceberg.

Using less fuel per mile is great. But using less fuel to accomplish the same ends is the real magic. Same for the TT: how to lower the per-night cost through longest ownership and highest use.



.

* This post was last edited 02/24/12 11:02am by an administrator/moderator *   View edit history


1990 35' SILVER STREAK Sterling, 9k GVWR
2004 DODGE 305/555 ISB, QC SRW LB NV-5600, 9k GVWR
Hensley Arrow; 15-cpm solo, 25-cpm towing

K3WE

Missouri

Senior Member

Joined: 05/24/2005

View Profile


Offline
Posted: 02/24/12 05:10pm Link  |  Print  |  Notify Moderator

'68Monaco440HP wrote:

Some time.........................................................................


I think reading this thread reduces fuel consumption as much as all the tips and analysis, because hopefully you are not reading and driving at the same time driving. If it gets much longer, we may never go camping.

pasusan

PA

Senior Member

Joined: 05/13/2009

View Profile



Posted: 02/25/12 05:21am Link  |  Print  |  Notify Moderator

K3WE wrote:

'68Monaco440HP wrote:

Some time.........................................................................


I think reading this thread reduces fuel consumption as much as all the tips and analysis, because hopefully you are not reading and driving at the same time driving. If it gets much longer, we may never go camping.
I thought that was a very good post! I learned something that applies to us - our Hensley saves us gas. Never thought about steering correction wasting gas, but it makes sense and since we no longer have to do that we have become more fuel efficient. Yea!


Trip Pics

"I'm out here to enjoy nature -- don't talk to me about the environment!" ~Denny Crane

Susan & Ben ~
84 Bronco & 90 Award Classic 23 joined with a Hensley Cub


jims1

tx

Senior Member

Joined: 09/19/2010

View Profile


Offline
Posted: 02/24/12 07:57pm Link  |  Print  |  Notify Moderator

Forgot one

Drafting other vehicles..
Tuck up behind a bigrig and your mileage will increase considerably.
Of course the big rig can and will outbrake you!


'06 Ram with a Cummins
'09 36MAX1 Carrilite
Me, Alie, and Salie
Fulltiming

This Topic Is Closed  |  Print Topic  |  Post New Topic  | 
Page of 3  
Prev  |  Next

Open Roads Forum  >  General RVing Issues

 > Identifing Fuel Economy factors
Search:   Advanced Search

Search only in General RVing Issues


New posts No new posts
Closed, new posts Closed, no new posts
Moved, new posts Moved, no new posts

Adjust text size:

© 2014 RV.Net | Terms & Conditions | PRIVACY POLICY | YOUR PRIVACY RIGHTS