Quick vs Gradual Acceleration in large vehicles.

[lselse3]

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.

[SentraSE-R]

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.

[elhigh]

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."

[mikeyjd]

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.

[fidalgoman]

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.

[elhigh]

^^
<Stomps gas for steep hill>
<Instant mpg readout drops to 10>
"Son of a..."

[justme1969]

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.