Slowing down to save fuel and increase

[Bruno]

I know a team that I consider friends that have slowed down to increase their truck MPG. By doing this they also saved a lot of money in fuel costs. You would be surprised how high you can increase MPG when you slow down. Team Caffee from FedEx Custom Critical has a Blog on EO in regards to it. Henry Albert the 2007 Overdrive driver of the year, has a blog that he posts on for everyone to see how he has got his Frieghtliner tractor trailer up over 9 mpg. Check out his link below. So what are you doing to increase you MPG?


Slice of Life link with 2007 Overdrive driver of the year Henry http://sliceoftruckerlife.com/blogs/henry-albert/Albert

 

[moose]

driving eastbound .

 

[teamjdw]

shut the truck off while going down hill.

 

[MissKat]

We use the cruise control. We travel at about 3-5 miles under the speed limit in most places unless the speed limit is 55. Then the rule doesn't matter. We don't do over 65 unless a wind is pushing us or gravity does.

 

[geo]

differents between 65 and 70 mph is 5 min's
and 3 miles per gal in a sprinter

 

[LDB]

Slowing down 4-5mph will also drop the rpm several percent as well, especially on a diesel. Besides the money that stays in your pocket in the form of unburned fuel there's also the reduced wear and tear on the engine at 1450 vs 1600 rpm for example. You've got less brake wear, less heat build up, more time to respond to an emergency, all combined with the direct fuel savings.

 

[Turtle]

I use Air Tabs.

 

[ebsprintin]

I'm wondering if driving slow is the reason I go through less windshields than what others claim to go through.

eb

 

[Turtle]

I dunno. My last chipped windshield came while driving 35 MPH when a flatbed passed me at 40 MPH in Falfurrias, TX as we were slowing down coming into town.

 

[scottm4211]

Might not have happened at 33 Turtle.

 

[TeamCaffee]

Thanks DaveWe have always driven very slow and have been asked often how are new truck would handle a higher speed which is why we are testing this.Henry Albert has always driven around 65 MPH as it relates better with other T/T drivers who he is more in contact with. He has been asked many times how his truck would perform at a slower speed so while we are speeding up he is slowing down. It is not always good to drop the RPM to slow as it will get out of the power band and hurt your fuel mileage as well as other things. I have heard this can harm your engine.We are running a heavy load for us today and it will be interesting to see what the higher speeds with this load will produce for fuel mileage. The test I imagine will end up as it depends.... If we can deliver the load a day early and be available for another load it will be worth it. We are figuring out how much the extra speed costs us in the future we could step it up under certain loads. We will run the test at least another week are two to get a good feel for what the speed has done to our fuel mileage. Henry Albert is seeing very good results with slowing down and he will probably also end up with an it depends situation. Since he is runs pretty much a dedicated route and is home each weekend he has to decide how much his home time is worth. It has been interesting to see his engine reports and his experiences on his blog. We will start blogging again tomorrow on how the test is going.

 

[greg334]

You know what funny, most ignore the way the engine works and only see what they want to see.

I mean there are two types of engines in our trucks, one medium duty and one heavy duty. There is a purposeful design in these engines, a sweet spot or where the engine's volumetric efficiency peaks. Many know this but what they may not know is that this is a small window, not a cliff.

By the way Mercedes 5 cylinder and v6 and GM/Ford Gas engines also have them but let's look at the two most common truck engines.

My ISC, a medium duty engine has a sweet spot at 1800 rpm, which the truck is properly geared for 65 at this engine speed. I run it at at ~62 mph and it provides the best mileage.

Now one of my other trucks has a Mack MP in it, a heavy duty engine has its sweet spot is around 1550 rpm so the truck is set up for that engine speed at 65.

Both trucks if run at a slower speed get an increase in fuel consumption and that is what happens to be forgotten, the trucks engine operates outside the window I mentioned before, so it uses more fuel. I already posted in Linda's thread what happens when I do slow down in my little truck but the Mack will lose a little more than 4% of fuel mileage because the engine is operating outside that window.

A lot of "expediting" trucks are not geared right that I've seen. Some will get better mileage at 55 than at 63 or 65. Many tractors are not geared right because a lot of them until recently didn't spec them for mileage but power.

Now you can point to Henry's blog for this info but he's running a tractor and does not matter for many of us. However some of the things he talks about on the business end are useful to us are ignored here and trashed, like what I did and have been doing to get good work. Henry's a good source for some info but he doesn't have a fleet, he runs one truck and he is in a different world.

If you really want to dig into this with better explanations and solid testing, go to Kevin Rutherford's site and read his take on all of it. A lot of people have better conversations about fuel consumption, fleets and the technical aspects of all of it.

 

[RETIDEPXE]

A lot of "expediting" trucks are not geared right that I've seen. Some will get better mileage at 55 than at 63 or 65. Many tractors are not geared right because a lot of them until recently didn't spec them for mileage but power.

True, but I still maintain the law of physics should be considered above all. We have driven St trucks with both 5:11's and 3:73's and found both do better dropping to 5th gear in the Allison 6 spd and running 57-58mph. Aerodynamics play a part but the slower speeds take less boost and fuel to pull it thru the wind to the tune of avg'g 9.5 vs 8.5 mpg at 65 mph in 6th. Now, if we have a nice 30+ mph tail wind like we did coming across I-10 in the west the other day, kick it up to 6th gear.....we pulled 11.5 mpg for 550 miles with our Cat C9 doing this.

One item I have added that I use to improve mpg, I have tapped into the cruise switchs (rocker and on/off switch) and ran wires to a second set of switches at the top of the drivers door within easy reach (our M2 has the factory switches on the dash and not easy to reach). I tap it down a couple notches on slight down slopes and cut it completely off on the better downgrades and also when heading up an incline and feather my way over the hill. Electronically controlled motors will shut the fuel flow off completely when coasting while in gear (if you want to call it coasting), but not when coasting in neutral. I've tried the neutral coasting thing, but leaving the truck in gear with the cruise off has better mpg gains because of the computer controlled motor.

Working the cruise as above, I will avg 10.5 mpg in the hills running 57-58 mph. I maintain this speed as close to as possible when not interfering with traffic. I drive the nite shift so not a lot of traffic then, but in heavier traffic I try to stay with the flow so as to not cause excessive lane changes to get around me. Safety first. Over the past couple years when we started doing this, we have saved 10% on fuel cost, roughly $5500/yr.