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Jason
Dodge Dakota
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4/22/2002
02:34:59
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 Subject: BETTER MPG!
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I have a 2002 3.9L Dakota, and was wondering what kind of mods should I do to get the most MPG, I am not concerned about about racing and getting more performance, just want more MPG, thanks!
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Diver_Climber
GenII
4/22/2002
07:17:54
|  RE: BETTER MPG!
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Message:
You need to look at what the mods do:
1. Allow the engine to operate more efficiently (new plugs, wires, 180 tstat).
2. Reduce the working load on the engine (new electric fan).
3. Allow the engine "breathe" easier (Larger TB, K&N intake, cat back).
4. Get more fuel into the engine (upgraded injectors, IAT relocation).
As a general rule, anything the reduces the load on the engine or makes it run more efficiently will also increase the MPG. You'll probably get a nice perf boost, too. The intake and exhaust mods might buy you MPG, but you also might burn more gas if you have a lead foot. Getting more fuel to the engine will not help MPG. It may not hurt it, but it certainly won't buy you anything.
Hope this helps.
Cheers,
DC
1994 SLT v6 5Spd, 180 Tstat, 3923 Autolites, Splitfire wires, K&N Filter, Black Magic 150, AutoPC with GPS
On Order: V8 TB, Borg Warner cap & rotor, Accel coil
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Glenn
Dodge Dakota
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4/22/2002
07:55:39
|  RE: BETTER MPG!
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I suggest a bed cover or cap for a good increase of mpg. It is functional and will definitely help fuel mileage.
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Texas97
*GenIII*
4/22/2002
12:17:20
| RE: BETTER MPG!
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Message:
I have to disagree with the bed cap as helping miles per gallon. Being an engineer student I have studied aeroedynamics and our trucks are designed to have the wind deflected off the cab and over the bed and tailgate. It creates a void, or vortex, behind the cab. The bed cap wont hurt anything, but you have to remember if it is heavy (100-150 pounds, like some i have seen), it can cause mpg to go down. It would be like having a payload all the time. Just my two cents but dont expect a cover to really increase mpg.
Kick the tires and light the fires!
97 Dakota CC 3.9L 5 speed
Flowmaster 40 Deltaflow , K&N Home Brew intake, Autolite 3923's, 180 t-stat, stock 5.9L V8 TB
Soon: FMS Injectors, No Cat, Electric Fan, IAT Adjuster(when it gets here)
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R/Truck
Dodge Dakota
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4/22/2002
12:28:05
| RE: BETTER MPG!
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Message:
How much do you really think can be gained in MPG? Does spending time and $ to gain 1-3 MPG really going to make a big difference?
If you fill up 4 times a month and your getting 1-3 MPG better gas mileage, that amounts to savings of approx. $100 / year. whoopie!
Buy a Geo or Honda if you want good gas mileage.
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DakotaCC
Dodge Dakota
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4/22/2002
12:36:42
| RE: BETTER MPG!
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Message:
A while back someone posted here a URL to a 1997 study undertaken by engineering students at Western New England College. Sorry, I don't have the URL here at work. Their study showed conclusively that adding a bed cover (tonneau cover) made a significant reduction in drag, using a Dodge Ram as the wind tunnel test vehicle. A reduction in drag *should* translate into an increase in fuel economy.
I'll post the URL if I find it at home.
Best,
DG
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Texas97
*GenIII*
4/22/2002
12:45:57
| RE: BETTER MPG!
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Message:
Huh... that would be very interesting to see. If it did make a significant difference, then Chrysler did not do very good wild tunnel tests on our trucks, or they neglected to test them at different speeds under 70. Keep in mind what I posted above should be applicable in theory, and theory can always be proved wrong my expiramentation. I dont want to sound like I know it all, thats just what interests me and thats what I have learned in my schooling.
Kick the tires and light the fires!
97 Dakota CC 3.9L 5 speed
Flowmaster 40 Deltaflow , K&N Home Brew intake, Autolite 3923's, 180 t-stat, stock 5.9L V8 TB
Soon: FMS Injectors, No Cat, Electric Fan, IAT Adjuster(when it gets here)
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Jason
Dodge Dakota
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4/22/2002
13:18:24
| RE: BETTER MPG!
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Message:
so basically, the IAT relocation wont help MPG?
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R/Truck
Dodge Dakota
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4/22/2002
13:23:34
| RE: BETTER MPG!
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Message:
No, making the IAT read cooler air will richen up your mixture. Makes for speed not MPG.
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NJQCDak
GenIII
4/22/2002
13:29:47
| RE: BETTER MPG!
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Message:
Here's that aerodynamic website:
http://mars.acnet.wnec.edu/~ehaffner/did.htm
With all my mods and tonneau cover I think I increased my mpg upto 19-20. It's hard to lay off the pedal. That ruins the MPG.
'01 QC Sport, 3.9L V6, 5spd, 2wd, Volant Intake,
SS Gibson exhaust, MSD Wires, Accel Super Coil, NAPA Cap, Flometrics Billet 48mm TB , JBA Silver Ceramic Headers, Autolites 3923s
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OffRoadRuss
Dodge Dakota
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4/22/2002
13:32:27
| RE: BETTER MPG!
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here is the link to the study regarding air drag and covers...
http://mars.wnec.edu/~ehaffner/did.htm
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nmdcommguy
Dodge Dakota
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4/22/2002
13:53:59
| RE: BETTER MPG!
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Message:
FREE MODS:
remove the tailgate.
remove the spare tire & jack.
remove any seats you aren't using.
don't carry anything that isn't needed on that trip.
OTHER FREE THINGS:
don't run your air conditioner.
keep your lights off unless it's dark or raining - don't use fog lights.
accelerate as slowly as possible (within reason).
anticipate stops and slow down without stopping.
avoid using your brakes (that just turns gasoline into heat).
avoid idling- you are getting zero mpg while waiting at a stop light.
plan your trips to minimize miles.
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MikeC
Dodge Dakota
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4/22/2002
14:08:55
| RE: BETTER MPG!
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I get about 40-50 more miles out of a tank with the tailgate down.
This is highway driving at about 70mph.
MikeC
2001 CC 4.7 4X4 SLT
3" Body Lift - Whoopie!!
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TommyBoy
Gen III
4/22/2002
20:49:17
| RE: BETTER MPG!
IP: Logged
Message:
I hate to disagree with people, but Texas i really do feel a huge difference with my hard tonneau cover. i now average about 50-60 more miles out of a tank of gas than i did without it. you can even feel that the truck feels almost lighter, even though its not of course.
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Texas97
*GenIII*
4/22/2002
21:54:42
| RE: BETTER MPG!
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Message:
I stand corrected.
Kick the tires and light the fires!
97 Dakota CC 3.9L 5 speed
Flowmaster 40 Deltaflow , K&N Home Brew intake, Autolite 3923's, 180 t-stat, stock 5.9L V8 TB
Soon: FMS Injectors, No Cat, Electric Fan, IAT Adjuster(when it gets here)
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NiPs
Dodge Dakota
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4/22/2002
22:05:44
| RE: BETTER MPG!
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Texas97 - I think your missing parts of the theory's. You see the wind will be better off with a cover simply because all that your changing is the bed which limits the amount of wind resistance from the tailgate. The wind flowing over the truck does split as some hits the inside of the bed the tailgate and all else. So a cover helps how much is another question. The drag coefficent isn't significantly altered and as such the faster you go themore important it is. Thus a slow speeds it's more a matter of weight. The hard covers can decrease city mileage if you have a lead foot thus constantly accelerating. Now a hard cover can actually increase your 60' times but lower your quarter mile, if your truck is sufficently fast enough to use the little extra areodynamics.
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Texas97
*GenIII*
4/22/2002
22:16:54
| RE: BETTER MPG!
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Message:
NiPs..
I know it will be better off with a cover because the smooth surface will let it roll right off. But will it be better off to warrant the money for it was my point. Like you said, it helps, but how much is the question. Some people have come forward saying that it helps which is great. I just didnt think in theory, that the cover would help that much for the price, but obviously I have been proven wrong by people who actually have covers on their trucks. This is good b/c they actually have evidence that it helps and thats what the original post was looking for. As I said before I am eating a mouthfull of crow right now!:)
Kick the tires and light the fires!
97 Dakota CC 3.9L 5 speed
Flowmaster 40 Deltaflow , K&N Home Brew intake, Autolite 3923's, 180 t-stat, stock 5.9L V8 TB
Soon: FMS Injectors, No Cat, Electric Fan, IAT Adjuster(when it gets here)
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92dakotahd
GenII
4/23/2002
01:48:48
|  RE: BETTER MPG!
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Message:
How accurate are wind tunnel tests for the real world though? I know this may seem stupid but I have had the wind direction alter my mileage by up to 150 miles a tank (NO JOKE.) My average is around 240-260 a tank. I never push it though. My all time best is 405 miles to a tank on vacation once. And that was loaded with a bed full of luggage and a tarp over it. But I've had tanks as bad as 180 miles with some bad driving.
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dbbaker
Dodge Dakota
JOIN HERE
4/23/2002
19:54:41
| RE: BETTER MPG!
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Message:
why do ya think nascar trucks have covered beds?
obvously it helps aerodynamics and speed. or they would be running around with their tailgates open too lol...
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