Engine/Transmission (1998.5 - 2002) great fuel mileage

[WestTN]

I have been running Smarty tune # 7 for well over a year, and lately hve slowed to 55 mph. We have great 4 lane divided highways here, so no conflict with people travelin faster. The last several tanks have yielded 23+ mpg.

I recently decided to try the fuel saver tune. My last fill came after 319. 5 miles of driving as I described above except 90 miles were travled at 65 mph with the A/C on, and the different Smarty tune. The result was 24. 67 mpg. Now I'm wondering if I can get 25!



Tire pressures at 60 psi, no fast starts, no idling, no fast acceleration.



Gotta love that Smarty!!!

 

[JDiepstra]

That's great. Which vehicle in your sig gets better mpg's?

 

[FLynes]

... and lately hve slowed to 55 mph.

Great minds think alike!!!:-laf:-laf:-laf I started doing that a few months ago, when fuel prices started going through the roof. #@$%!

... I recently decided to try the fuel saver tune. My last fill came after 319. 5 miles of driving as I described above except 90 miles were travled at 65 mph with the A/C on, and the different Smarty tune. The result was 24. 67 mpg. Now I'm wondering if I can get 25!



Tire pressures at 60 psi, no fast starts, no idling, no fast acceleration.



Gotta love that Smarty!!!

Did you notice any difference, performance-wise, with the fuel saver on? By that, I mean did the truck suck when you accelerated?



Thanks for the answers.

 

[WestTN]

The fuel saver setting surprisinly adds pretty good additional power over stock when you step on it.



The PT Turbo HO gets slightly better than the truck, but not much. Of course it was designed to run the quarter mile in 14. 3 seconds, which is what the stock 1968 440 Magnum Dodge Charger did.

 

[Crazy Horse]

I have been running Smarty tune # 7 for well over a year

That's what I've been running w/ my Smarty. Power level #7. I also have had mine for a little over a year and a half now. My average MPG since running the Smarty is now sitting on 23. 4. That's the average since (Sept 06) the new lift pump (Walbro) and when I began running the Smarty. I'm trying for 24.



On the old I-85 it's hard not to run over 75mph. I usually run between 75 and 85 depending on traffic. If I make one trip into Spartanburg/Greenville (120 miles round trip) 55-65mph I can increase my mileage by 2-3 10ths; bumping the 23. 4 to 23. 7mpg. That's driving the back road nice.

 

[DRanger]

I drive a 92 dodge d250 2wd and get about 25 mpg mixed highway and city. Only thing thats on my truck is the Banks larger exaughst and turned up fuel pump so I dont Know.

 

[dram99]

65 on a 1365 mile trip

i just came off of a trip from minneapolis to bismarck nd. . 1348 miles... i pulled an empty car trailer for the first 160 miles, droped off the trailer and stayed overnight with some local driving. the next day i drove to bismarck, this would be about 450 miles total. i did alot of local city driving. on the way back to minneapolis i stoped off and picked up the car trailer and loaded a jeep wramgler with a 4" lift and 33x12. 5x15 tires (high profile, low weight). another 160 miles back to minneapolis. . i filled fuel and did my calculations using the fuel added and miles driven. . this came to 24. 564472, d_m!!!!

i drove 65 mph on I94 and the speed limit on other roads and my truck is stock with 192k miles

original lift pump, injector pump, amsoil sythetics all around.

Don't mandate lower speed limits, make it a persoan choice!!!!

 

[johncameron]

I've been getting over 20MPG at 70MPH with my truck lately on SW1. I havn't done any long runs going slower but I sure slowing down even to 65MPH would gain me 1+ MPG.

 

[Drewhenry]

27+

Lots of folks show me their IQ,or are they telling me I am#1,when I drive 55. Who knows. I recently made a trip to Cleburne, Texas. By the overhead and by hand calculations I got just a hair(27. 977) under 28 miles to the gallon. Granted I was running empty, but there ain't a 3/4 ton gasser out there that will even come close. I can't wait to get Smarty and see what I can do then. My truck is still stock. I have been considering a gear swap to 3. 42 front & rear, but not sure how much good it will do. I would like 3. 07 if they became available.

55 is a magic number. I wish the national speed limit would be reduced. It certainly would save a tremendous amount of fuel. My next question will be: Are the highway ratings on automobiles showing test results of driving 70mph or 55mph. My guess is mpg based on 55mph. Any thoughts?

Another thought. When did overdrives start appearing on light duty trucks? Was it during the gas crunch of the 70s?

Andy

 

[johncameron]

I think factory MPG's are figured at 48MPH!!!!!!!!!!!

 

[Drewhenry]

I think factory MPG's are figured at 48MPH!!!!!!!!!!!

Probably. Running empty I get better mpg in direct@48 than od @70.

 

[johncameron]

Probably. Running empty I get better mpg in direct@48 than od @70.

I don't know, I've never compared them. I couldn't drive 48MPH for 2 tanks:-laf

 

[Hobart]

Will the fuel saving setting add too much horsepower and tear up my transmission? I've got a VA now and the extra HP is 60 I think; maybe I get 1 to 2 extra MPHs. With the camper I'm getting an average 13. 5. Sure would like to see 15mpgs.

 

[BSMcCauley]

... By the overhead and by hand calculations I got just a hair(27. 977) under 28 miles to the gallon. Granted I was running empty, but there ain't a 3/4 ton gasser out there that will even come close...

I second that. Quite a while back, I had a HP/Torque curve from Cummins for the 6BTA (for an industrial application) that also had the basic fuel consumption curve on it. The chart indicated that the 12V made the most HP/LB fuel/hr at 1480 RPM (also happened to be the peak on the torque curve on that chart). Anyway, I had a 325 mile non-stop trip, nearly all flat-level hwy, each week back then so I topped 'er off clear to the top of the fill neck and set off down I-10 from Katy, TX to Morgan City, LA with the cruise control set just shy of 1500 RPM. Result? 27. 87 MPG. I was sure the filling station's pump was off when I got to where I was going, so I did it again on the way back (through the driving rain this time) and got 27. 37. :-laf While I do believe that wind drag has a huge impact on MPG above 70 MPH, I'm also convinced that elevated engine RPM when the power isn't needed also sucks the fuel. Incidently, I usually get around 19 hwy / 17 city, so you get the picture of how I normally drive... . I've run the numbers several times haven't made an aux overdrive pay out yet, but if the fuel price climbs much more the economics might start paying out.



Truck setup for the high MPG test: stock running gear, 3. 54 axles, LT235/85R16 tires @ 80 psi.

 

[Jeremiah]

Before I retired from law enforcement, some compadres and I followed two bad guys with a load of cocaine all the way from Miami to Colorado. They drove non-stop (except for gas and an occasional burger from a drive-thru) at 45 mph. The reason they could do that is because they were sniffing that s**t to stay awake. They were driving that slow because they didn't want the highway boys messin' with 'em. It was the worst trip I've ever made and whoever said the speed limit on highways should be reduced to 45 mph has been sniffin' somethin' stronger than cocaine.

 

[AKaiser]

55 is a magic number. I wish the national speed limit would be reduced. It certainly would save a tremendous amount of fuel.

I'll take a pass on the nationwide 55 BS, except for trucks, but only if there are more than 2 lanes each direction. OH's stupid 55/65 speed limit just causes congestion on 4-lane divided highways, but it's a non-issue on 6-lanes. By forcing freight to travel 55, that might cause more to go on rail, which is vastly more efficient, energy-wise, and if not, it would employ more drivers to push the same load per day. Since energy costs per mile go down either way, that would help offset the revenue loss per driver.

Those of us who don't drive for a living pay for it in fuel taxes, and frankly, if I have to drive more than an hour one way, anything less than 65 doesn't cut it on a multi-lane divided highway. It's NONSENSE. Don't want to drive over 55, do what I do: take a 2 lane state highway or backroads. I do this every day, and it may take an extra 15 minutes each way, but I save a mile or two per gallon doing it.

Oh, and who the heck are these knuckleheads driving economy cars on the interstate at less than 60 in a 70? It's an ECONOMY car. You're not going to gain much when you're already getting 35 MPGs anyway,and you are a danger to everyone including yourself in heavy traffic when prevailing speed is high. And who are the boneheads that don't know you don't dawdle in the entry ramp. Besides best fuel economy is achieved with moderately brisk acceleration to cruising speed, not wasting energy at part-throttle where pumping losses are an issue.

 

[WestTN]

AKiaser, whether you care for it or not, the best fuel mileage is at about 41 mph because that is where aerodynamics has placed it. My truck will get ~23 to 24 at 55 t0 60 mph and about 26 mph at 50 to 55. I haven't tried it at anthing much lower.

 

[AKaiser]

AKiaser, whether you care for it or not, the best fuel mileage is at about 41 mph because that is where aerodynamics has placed it. My truck will get ~23 to 24 at 55 t0 60 mph and about 26 mph at 50 to 55. I haven't tried it at anthing much lower.

That's just fine and dandy. It is what it is, and if I want it, I can drive (and do drive) backroads to get it. Keep in mind that it's not true for all vehicles, either, due to gearing.

I'm not going to accept excessive government interference bringing slow speed limits to high speed routes. Want to reduce energy use? Find a better solution. Don't waste my time. Every minute I'm on the highway is a minute I could have spent doing a. something productive, b. something enjoyable, or c. both a and b.

 

[BSMcCauley]

I'm not going to accept excessive government interference bringing slow speed limits to high speed routes. Want to reduce energy use? Find a better solution. Don't waste my time. Every minute I'm on the highway is a minute I could have spent doing a. something productive, b. something enjoyable, or c. both a and b.

I have to agree. As stated earlier in this discussion thread, I've documented 27. 87mpg over 300 miles of flat/level highway with no wind, running empty with the cruise control set at 1500 RPM (55mph). However, if I, along with countless others, will spend $3. 00 twice a day circling Houston from US-59 to I-45 trying to save 15 minutes, it doesn't make much sense to contemplate spending 2:25 trying to save $17. 50 in diesel fuel over a 500 mile trip. My time is worth a lot more than that, and so is yours. The scant minority of folks willing to put their life on hold and travel at 45 mph are more than welcome to do so AT THEIR OWN CHOICE! They have no business requiring me to do to likewise.

 

[Troubleshooter]

Interesting that y'all are getting such great mileage, even at higher settings. Makes me wonder what gears your trucks have. Using SW#1, mine averages 20. 5 - 21 mpg in combined city and highway (mostly two-lane roads, 55mph and 20-30 mph in town). On a recent longer trip, the best that it got was 23. 5mpg along a stretch of interstate at the posted speed limit of 75mph. I hadn't considered using the higher settings such as SW#5 for that particular drive, since I was unloaded and didn't need the power as much as the fuel mileage.



Regarding the comments on speed limits: I agree that we don't need the feds dictating any mandatory lowering of limits. Had enough of that under the Nixon administration and don't care to go back. But that said, I do tend to drive the posted speed limits, and especially in town (kids) and two-lane highways (other hazards). Some time back, I got my first speeding ticket since the one 16 years previously, and decided that, barring an emergency, there was no place that I needed to be that justified the cost or hassle. So I drive the posted limit now; if you don't like it, pass. Just don't whine to me when the state trooper or sheriff's patrol writes you a ticket.