Where 7 mpg is Good - Fuelly Forums

Android Users - Coming Soon! - Migrating from aCar 4.8 to 5.0

Reply
 
Thread Tools Display Modes
 
Old 09-06-2009, 07:06 PM   #1
Member
 
Join Date: Oct 2011
Posts: 43
Country: United States
Where 7 mpg is Good

I saw on an older topic where someone mentioned they wished their was a real truck driver on site for feedback. It got me to thinking you might be interested in my "Work Drive".

Im a contractor with a large transportation company who runs the same terminal to terminal run every night. I thought you might be interested.

Vehicle - 2006 Freightliner Columbia with Double 28' Pups.
Weight - 20x typical car (53,000-80,000 lb)
Rolling Resistance - 22x typical auto (22 tires with 4x the rolling resistance each)
Air Drag - 12x typical auto (115 sq ft x 0.68 cd estimate)
Powertrain - 470/515 bhp - 1650 torque (Increased output in cruise) 14.0L S60 Detroit with 13-Spd Double OD Trans (0.73 Top Gear).
Drive Tires - Michelin XDA3 275/80R24.5 (493 rpm)
Engine Rpm - 1403 rpm @ 65 mph (Factory Spec with brand new tires)

Run - 202 mi x 2 over mixed roads with a maximum of 4 hours run time for each leg. Primarily rural non-limited access 4 lanes with a 65 mph limit.

Driving Technique - Get it over the top at minimum rpm in top gear and give minimum throttle (Sometimes none) to reach 61 mph by next flat. I use moderate throttle in lower gears leaving redlights in deference to the drivetrain (20,000 lb of torque is hard on ujoints). 1400-1600 rpm shifts in lower gears. 1300-1500 shifts in uppers (I can split these gears).

Note: In a 13 speed you have - A low you only use in extreme situations, You normally use 1-4 and then change ranges and go through 5-8 (Which are the same locations 1-4). You farther have a seperate OD on the back of the trans that only works in the "upper" gears which allows you to "split" the upper gears.

Cruise Speed - 1350 rpm (61 mph with current tire wear) where legal.
Average Speed - 58 mph
Note: The truck averages the best at 61 mph due to forced downshifts on hills at lower speeds.

Mpg - Average 7.2 mpg (6.8-7.3)

Mpg Various Cruise Speeds -
1200 rpm (54 mph) - 7.5 mpg
1250 rpm (56 mph) - 7.8 mpg
1300 rpm (59 mph) - 8.0 mpg
1350 rpm (61 mph) - 7.8 mpg
1400 rpm (64 mph) - 7.5 mpg
1450 rpm (66 mph) - 7.2 mpg
1500 rpm (68 mph) - 6.9 mpg
1550 rpm (71 mph) - 6.5 mpg


Note: this includes an average of 10 stops per trip (Stop Signs, Lights, Scales) and approximately 1 gal used at each end for assembly and disassembly of sets.
__________________

GeneK is offline   Reply With Quote
Old 09-06-2009, 07:30 PM   #2
Registered Member
 
GasSavers_RoadWarrior's Avatar
 
Join Date: Feb 2008
Posts: 1,652
Nice info.

Why do you peg the rolling resistance so high though? Large diameter high pressure tires with a hard compound should have less RR than a car tire.
__________________

__________________
I remember The RoadWarrior..To understand who he was, you have to go back to another time..the world was powered by the black fuel & the desert sprouted great cities..Gone now, swept away..two mighty warrior tribes went to war & touched off a blaze which engulfed them all. Without fuel, they were nothing..thundering machines sputtered & stopped..Only those mobile enough to scavenge, brutal enough to pillage would survive. The gangs took over the highways, ready to wage war for a tank of juice
GasSavers_RoadWarrior is offline   Reply With Quote
Old 09-06-2009, 07:41 PM   #3
Registered Member
 
imzjustplayin's Avatar
 
Join Date: Dec 2011
Posts: 720
Country: United States
Yeah rolling resistance is kind of irrelevant anyways, the main point should be that per the weight, a semi truck is far more efficient than MOST cars and light trucks.
imzjustplayin is offline   Reply With Quote
Old 09-06-2009, 08:00 PM   #4
Member
 
Join Date: Oct 2011
Posts: 43
Country: United States
Quote:
Originally Posted by RoadWarrior View Post
Nice info.

Why do you peg the rolling resistance so high though? Large diameter high pressure tires with a hard compound should have less RR than a car tire.
It could be inaccurate. I once read that a typical loaded truck tire had 4x the rolling resistance of a car tire. It might be because the truck tire might have up to 6000 lb on it versus 900 lb for a typical passenger car tire.
GeneK is offline   Reply With Quote
Old 09-06-2009, 09:40 PM   #5
Registered Member
 
Join Date: Apr 2007
Posts: 336
Country: United States
nice info... if a truck company can crack 10mpg on those things, they will make a ton of money
civic94 is offline   Reply With Quote
Old 09-06-2009, 11:45 PM   #6
Member
 
Join Date: Dec 2006
Posts: 59
Country: United States
Somehow it's still more cost-effective by truck than by railway transportation!
markweatherill is offline   Reply With Quote
Old 09-07-2009, 03:49 AM   #7
Registered Member
 
theholycow's Avatar
 
Join Date: Apr 2008
Posts: 6,624
Country: United States
Send a message via ICQ to theholycow Send a message via AIM to theholycow Send a message via MSN to theholycow Send a message via Yahoo to theholycow
Great compilation of data! Thanks!
__________________
This sig may return, some day.
theholycow is offline   Reply With Quote
Old 09-07-2009, 05:02 AM   #8
Registered Member
 
Join Date: Apr 2008
Posts: 1,259
Country: United States
Location: wiliamsburg virigina
Imagine the mileage you could get in a car if it was very aero and driven like the trucks, especially one with all of the high mileage tweaks used by truckers.

regards
gary
__________________
R.I.D.E. is offline   Reply With Quote
Old 09-07-2009, 05:24 AM   #9
Registered Member
 
bowtieguy's Avatar
 
Join Date: Oct 2008
Posts: 1,873
Country: United States
Location: orlando, florida
i'd say 7 is good. i drive a straight truck w/ a refer(cold) unit. our trucks get from ~4 to 6mpg depending on the route, but being local delivery, we have many more stops than you do. i've often wondered what we could achieve w/out the refer running.
bowtieguy is offline   Reply With Quote
Old 09-07-2009, 06:04 AM   #10
Registered Member
 
GasSavers_RoadWarrior's Avatar
 
Join Date: Feb 2008
Posts: 1,652
Quote:
Originally Posted by Tightwad View Post
It could be inaccurate. I once read that a typical loaded truck tire had 4x the rolling resistance of a car tire. It might be because the truck tire might have up to 6000 lb on it versus 900 lb for a typical passenger car tire.
Ah right, I'm thinking of the RR coefficient being lower, something like 0.006 vs 0.015 for typical truck vs typical car, but that's multiplied by the weight on them for the total RR. So actual rolling resistance would be 0.006x6000=36 vs 0.015x900=13.5, so yup, could be 2-4x higher depending on what weights and tires you pick for the example.
__________________

__________________
I remember The RoadWarrior..To understand who he was, you have to go back to another time..the world was powered by the black fuel & the desert sprouted great cities..Gone now, swept away..two mighty warrior tribes went to war & touched off a blaze which engulfed them all. Without fuel, they were nothing..thundering machines sputtered & stopped..Only those mobile enough to scavenge, brutal enough to pillage would survive. The gangs took over the highways, ready to wage war for a tank of juice
GasSavers_RoadWarrior is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Two cylinder cars Sludgy General Fuel Topics 31 09-13-2011 02:20 PM
Opinions Wanted 91 CRX - How Bad Is This? Head Gasket and Block UfoTofU General Maintenance and Repair 30 05-21-2008 04:33 PM
How do u guys calculate miles per gallon? GasSavers_fuelmiser General Fuel Topics 29 07-02-2007 06:43 AM
MID Install SVOboy Experiments, Modifications and DIY 33 06-04-2007 11:27 AM
New to Site FormulaTwo Introduce Yourself - New member Welcome 15 09-20-2006 08:17 AM

Powered by vBadvanced CMPS v3.2.3


All times are GMT -8. The time now is 08:00 AM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.