Double kilotank: 2,009.6 mi on one 35 gal tank ('07 Dodge Ram 2500 quad cab)

[night9]

I know this is way off topic but I was curious about seeing your trucks speed vs mpg chart. It would be interesting to reference. Considering your style of driving, I would assume, has more to do with the amout of time the engine is off and the truck is coasting rather than true ability of the motor to sip gas.

[Diesel_Dave]

Originally Posted by night9

I know this is way off topic but I was curious about seeing your trucks speed vs mpg chart. It would be interesting to reference. Considering your style of driving, I would assume, has more to do with the amout of time the engine is off and the truck is coasting rather than true ability of the motor to sip gas.

I'm not sure how much a speed vs. mpg chart is really going to tell. Most all my driving is engine-off pulse and glide, so my speed is rarely constant.

I think the issue you're referring to is that fuel economy in terms of miles/gal has to do with two issues:
A) How much work/power is required
B) How efficiently that work/power is produced

Part A has to do with both drving style & non-engine vehicle mods. For example, driving slower (or aero mods) decreases the work required because there's less aero drag. Using less brakes also means the engine needs to produce less work per mile.

Part B is addressed by engine mods and, to a lesser extent, driving style. For example, I've switch to low weight synthetic oil, advanced the injection timing, added a ram cold air intake, etc. All these things mean I get more power from the same amount of fuel. The pulse and glide technique helps to, because it keeps the engine at higher loads where the engine is more efficient.

Recently, I've been using my loggers to try to get a handle on these two things (using vehicle speed, engine speed, ECM estimated torque, and ECM estimated fueling). According to that, I'm typically averaging about 0.22 hp-hr/mile and a BSFC of about 0.50 lb/hp-hr (~28% brake thermal efficiency). I'm not sure how accurate the ECM-estimated torque is, but those are the numbers I'm getting.

[Diesel_Dave]

Also, I've been going through some of my loggers. I thought this was an interesting plot, showing how much distance I travelled in differnt speed ranges.

[Joggernot]

Just for an example of poor aerodynamics...My 2005 Yamaha 1100 motorcycle gets (measured by me):

28 mpg @ 90 mph
33 mpg @ 70 mph
45 mpg @ 55 mph
54 mpg @ 45 mph

Let's us know that low Cd is good, but motorcycles are not designed for aerodynamic efficiency.

Joggernot

[mikeyjd]

It looks like the majority of your driving occurs between 50-20. Would you say that a typical glide on your main route is 50-20?

[Diesel_Dave]

Originally Posted by mikeyjd

It looks like the majority of your driving occurs between 50-20. Would you say that a typical glide on your main route is 50-20?

My communte is ~5 miles in town, followed by ~15 miles on fairly open highway, followed by ~5 miles in town.

In the in-town section I don't get up to 50 mph that often. On the highway section, I do typically pulse up to ~50 mph. How low I go depends on traffic. If there's no one around, I do sometimes go all the way down to 20 mph. Otherwise it depends on if someone's coming up behind me--it can be anywhere from 20 mph to 40 mph.

[bikeprof]

Dave, that is great that your mileage was way over the normal for a truck, and that is including lesser vehicles!
DOGS are the best friend a MAN has(most of the time/women at times).
Sorry for the loss, I know you miss your "puppy"...

My best on a 1996 VW Passat TDI variant has been 1,526 miles but on 26 gallons.
I'll get closer to your mileage record after my TDI goes to the doctor(one of these days :-).

[Hank1510]

I've seen your truck many times driving to and from work, and had a feeling you were hypermiling (the skirts are a giveaway). I had no idea the results were so good. I only coast to stop lights and draft at a reasonable distance. I'll try not to run you down while I'm cruising at 63mph.

Congrats! And sorry about your dog...

[Big Dave]

Post #43 is very useful.

What loggers do you use?

I suspect my speed profile shifts to the right.

[Diesel_Dave]

Originally Posted by Big Dave

Post #43 is very useful.

What loggers do you use?

I suspect my speed profile shifts to the right.

I've used the OBDWiz software (it's free). I can get Vehicle Speed over the OBD connection.