Go Back   EcoModder Forum > EcoModding > Hypermiling / EcoDriver's Ed
Register Now
 Register Now
 

Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 08-24-2013, 04:57 PM   #1 (permalink)
EcoModding Lurker
 
Join Date: Mar 2013
Location: Dallas Texas
Posts: 2

6.4 - '08 Ford F-250 XLT
90 day: 35 mpg (US)
Thanks: 0
Thanked 0 Times in 0 Posts
Quick vs Gradual Acceleration in large vehicles.

Howdy! Im kinda new to Ecomodder so for those who dont know me i am a freshman aerospace engineering student from Steamboat Springs colorado, but more importantly I am the loudest and proudest member of the fighting Texas Aggie class of 2017. With that out of the way, I have known for the longest time that it is said to be better to get up to speed more slowly. However, I drive a 2008 6.4 f250 diesel, with over 8k lbs of curb weight. I have a theory that in a heavy vehicle, it is better to hit the gas harder so that you get up to speed faster. I think it has to do with 2 factors. One, while accelerating, the transmission likes to stay in a lower gear, leading to higher Rpms and in efficiency. The biggest reason I feel as though it is more efficient to give it more gas from the stop is the fact that it is a TURBO diesel. If I attempt to gradually get up to speed, then the turbos do not receive enough exhaust to spool up, leading to less of a lean burn. If I give it a good amount of gas, the turbos spool up shortly, and allow the fuel to burn more completely, in turn, more power per unit of fuel, and reaching speed quicker.
Im just wanting to see what y'all think about this theory, not really asking any questions, just looking for discussion.
Sorry if that is hard to follow, Ill get better at makeing my posts easier to read.

  Reply With Quote
Alt Today
Popular topics

Other popular topics in this forum...

   
Old 08-24-2013, 05:52 PM   #2 (permalink)
Pishtaco
 
SentraSE-R's Avatar
 
Join Date: Jun 2009
Location: Bay Area, California
Posts: 1,485

Mean Green Toaster Machine - '06 Scion xB
Team Toyota
90 day: 48.92 mpg (US)
Thanks: 56
Thanked 286 Times in 181 Posts
It depends on the BSFC graph for your engine. Adding the variables of an AT and turbo only complicate the issue. Here's a way to measure and calculate fuel consumption during acceleration for any 1996 and newer vehicle.
__________________
Darrell

Boycotting Exxon since 1989, BP since 2010
Have you ever noticed that anybody driving slower than you is an idiot, and anyone going faster than you is a maniac? George Carlin
Mean Green Toaster Machine
49.5 mpg avg over 53,000 miles. 176% of '08 EPA
Best flat drive 94.5 mpg for 10.1 mi
Longest tank 1033 km (642 mi) on 10.56 gal = 60.8 mpg
  Reply With Quote
The Following User Says Thank You to SentraSE-R For This Useful Post:
IamIan (08-25-2013)
Old 08-24-2013, 06:15 PM   #3 (permalink)
Master Novice
 
elhigh's Avatar
 
Join Date: Jan 2008
Location: SE USA - East Tennessee
Posts: 2,311

Josie - '87 Toyota Pickup
90 day: 27.96 mpg (US)

Felicia - '09 Toyota Prius Base
90 day: 50.13 mpg (US)
Thanks: 424
Thanked 611 Times in 448 Posts
Like SentraSE-R said, find a BSFC chart for your engine - you might want to get some dyno time for your rig so you have a true, post-mods map of YOUR engine - and park your tacho there for acceleration. That is quite literally the most bang for the buck, right at the "island of efficiency."
__________________




Lead or follow. Either is fine.
  Reply With Quote
Old 08-24-2013, 10:03 PM   #4 (permalink)
Master EcoModder
 
mikeyjd's Avatar
 
Join Date: Mar 2013
Location: Grand Rapids, MI
Posts: 838

Matchbox - '93 Ford Festiva L
Team Ford
Last 3: 70.16 mpg (US)

Salamander - '99 Chrysler Concorde LXI
Team Dodge
90 day: 30.3 mpg (US)

Urquhart - '97 Toyota Tacoma 4x4 V6 3.4L DLX
Pickups
90 day: 25.81 mpg (US)

Smudge - '98 Toyota Tacoma
90 day: 40.65 mpg (US)

Calebro - '15 Renault Trafic 1.25 dci
90 day: 39.39 mpg (US)
Thanks: 1,380
Thanked 209 Times in 155 Posts
As the other guys stated it has to do with your engines best efficiency ranges. "Slower" and "faster" are relative terms and don't really aid the discussion much without qualifying the parameters of what they represent.
  Reply With Quote
Old 08-24-2013, 11:40 PM   #5 (permalink)
EcoModding Lurker
 
fidalgoman's Avatar
 
Join Date: Jul 2009
Location: NW Montana
Posts: 89
Thanks: 6
Thanked 21 Times in 19 Posts
You know the engine mapping control guide would give you a very good idea of what loads and speed ranges give the best efficiency. Don't products like ScanGauge read the computer map and interpret it into real world instantaneous MPG? A little practice and knowing when to shift would be all it takes to optimize FE.

I know from experience when you mash the pedal down hard and see FE go into single digits or low teens for a second it really gets your attention.

Last edited by fidalgoman; 08-24-2013 at 11:45 PM.. Reason: Because I can!
  Reply With Quote
Old 08-26-2013, 08:42 AM   #6 (permalink)
Master Novice
 
elhigh's Avatar
 
Join Date: Jan 2008
Location: SE USA - East Tennessee
Posts: 2,311

Josie - '87 Toyota Pickup
90 day: 27.96 mpg (US)

Felicia - '09 Toyota Prius Base
90 day: 50.13 mpg (US)
Thanks: 424
Thanked 611 Times in 448 Posts
^^
<Stomps gas for steep hill>
<Instant mpg readout drops to 10>
"Son of a..."
__________________




Lead or follow. Either is fine.
  Reply With Quote
Old 08-26-2013, 09:02 AM   #7 (permalink)
Master EcoModder
 
justme1969's Avatar
 
Join Date: Dec 2012
Location: ff
Posts: 459
Thanks: 59
Thanked 38 Times in 30 Posts
Good question!

I posted this similar answer before for another who diddnt really understand the question much less the answer.
All engines are designed to hit marks in performance then detuned to match requirements and meet warrenty expectations.
For the most part F/E was always back seat here in USA to torque and H/P.
IMHO it still is.
SO in your case WOT is not the sweet spot as fuel map becomes Linear untill Rpm is reached and Torque curve meets HP curve or just past that point.
In gas sucking pig cars Like My KIA the Torque curve begins at 1700 rpm and then fuel gets optimized.
In my Dodge Dakota R/T the foot goes down till I feel Gs. build then after 2900 rpm it is just sucking down fuel for fun if it diddnt empty the tank getting to there. Look into your calculated gear ratios and then read a baseline dyno sheet for your truck that will be enough to get you very close.

  Reply With Quote
Reply  Post New Thread


Tags
acceleration, heavy, large, truck, turbo diesel

Thread Tools




Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2022, vBulletin Solutions Inc.
Content Relevant URLs by vBSEO 3.5.2
All content copyright EcoModder.com