Towing effort?? - Montana Owners Club

Wiarton William · 08-02-2008, 01:24 AM

In conversation with another RVer the other day we chatted about the "sweet spot" where the RPM and vehicle speed are matched and everything sounds and feels great......I recall that with my last trailer it was about 62-65 MPH and about 1900 RPM...I recall that under that RPM and Speed the truck seemed to be Working and not happy doing it....With the new trailer I am about 2000 lbs heavier and I am not to eager to be getting into much speed......I wonder if I am going to get any better mileage by staying at a speed that gives the best mileage(50-55MPH) or going to a speed that everything meshes into an enjoyable towing trip..Assuming of course that the new unit and truck meet at the same numbers...

richfaa · 08-02-2008, 02:32 AM

Here is what I found with the 08, 6.4L Ford.. 63/65 seemed to be "The sweet spot" However on our last long trip we slowed to 60MPH and the MPG increased at least .5 to .8 mpg.

noneck · 08-02-2008, 02:58 AM

I "thought" the same thing...65 - 70 seemed to be great. Recent trip to Maine and back forced myself to stay 55 - 60 with some whoops and recoveries back to my conservative speed. Mileage improved much like Richfaa, went from 12 mpg to 13 mpg and my nerves are much less stressed.
Chuck

bsmeaton · 08-02-2008, 03:56 AM

Please just drive the speed limit and quit worrying about the mileage. We catch a bad rap as it is. People cannot pass us, and we put everybody at risk by driving 10-15 under the speed limit.

We're talking the difference between 10 and 11 miles per gallon. Soon enough everybody will be back to 55 in November, so lets enjoy the full blazing speed of 65 while we can.

Bill-N-Donna · 08-02-2008, 04:10 AM

In response to the original posting, the sweet spot that I have found is right at 70 MPH. Everything smooths out at that speed. When traveling at 55+/-, I have a vibration in the TV that is somewhat annoying. It takes the higher speed to run smoother.

Waynem · 08-02-2008, 06:37 AM

I stick it on cruise control between 62 and 64 mph. Seems to be what a lot of the truckers are running. I tried 55-60 and it did not like that speed (F350 6.0 Power Stroke) Shifting, down shifting, etc. The higher speed diminished that considerably.

As for fuel, it doesn't matter which of the two sets of speeds I'm running at. Depending on road conditions (mountains vs., flat) I get between 9.6 and 10.2 MPG. The only time I did better was in New Hampshire/Maine, on back roads, at 25-35 MPH. Then I got between 11 and 12. I'm just not up to doing 25-35 on a freeway. I'll stick to between 60-64, probably even if the speed limit goes down to 55. I do have to be careful as I have a Texas CDL and there is no forgiveness on tickets - no defensive driving, deferred adjudication, etc., just pay the high fine.

jjackflash · 08-02-2008, 08:14 AM

Quote:

quote:Originally posted by Waynem

I stick it on cruise control between 62 and 64 mph. Seems to be what a lot of the truckers are running. I tried 55-60 and it did not like that speed (F350 6.0 Power Stroke) Shifting, down shifting, etc. The higher speed diminished that considerably.

As for fuel, it doesn't matter which of the two sets of speeds I'm running at. Depending on road conditions (mountains vs., flat) I get between 9.6 and 10.2 MPG. The only time I did better was in New Hampshire/Maine, on back roads, at 25-35 MPH. Then I got between 11 and 12. I'm just not up to doing 25-35 on a freeway. I'll stick to between 60-64, probably even if the speed limit goes down to 55. I do have to be careful as I have a Texas CDL and there is no forgiveness on tickets - no defensive driving, deferred adjudication, etc., just pay the high fine.

I also have a CDL and last year I was caught doing 65 mph.
My insurance went up 400.00 a year and that's with not having a ticket in 20 years.
I checked with other insurance companies and can't find a better rate. I am sticking at 55 from now on.
Jack

**Rondo** · 08-02-2008, 08:44 AM

OK, where did I miss something? Reference to back to 55 for the limit in November! Where is this coming from and why?? I can see it in some states where they post the 55 but why 55 in November all over??

bsmeaton · 08-02-2008, 10:46 AM

Rondo - the feds are looking at it again because of the fuel issue, just like in the late 70s.

**Rondo** · 08-02-2008, 12:17 PM

Heck Brad, by November we could be back to $2.50 a gallon for diesel since the Congressmen all want our votes in the November election!

sreigle · 08-02-2008, 02:08 PM

Sorry, I'm not staying up with all those speed limits while towing. Some of those speed limits are 75 mph. If we get a parade behind us, we pull over and let them go. The difference between 10 and 11 mpg is about 10 percent. In our current fuel budget that is about $80/month or almost $1000/year. Nothing to sneeze at.

On my 6.7L Cummins with automatic and 3.73 rear gears that "sweet spot" seems to be 62 to 64 mph. That's roughly 1700 rpm. On flat roads sometimes I'll drop it down to 58 mph, about 1500 rpm, which seems just as sweet on the flat roads. But in hilly terrain 58 mph will often downshift out of the second overdrive (6th) to the first overdrive (5th). If I increase speed in hilly terrain to 62 to 64 it downshifts only on the steeper hills.

At 58 mph it's running about 1500 rpm. On this engine, that's not "working" (lugging?). The peak torque is at 1400 rpm and it's just purring at those speeds.

I don't have enough data to say I can accurately pinpoint the mileage difference between 58 and 64 on this truck. But, it appears to be about .2 or .3 mpg. If I tow over 65, then it drops more. I rarely tow 68 to 70 but did so twice last year, when my folks passed away. Mileage suffered but getting there quickly was our goal so we drove faster and did 400 to 500 miles per day.

stiles watson · 08-02-2008, 05:29 PM

I will not drive my rig 75 MPH, which is the speed limit down I 25 in Colorado. I do as has been suggested and pull over to allow a line of traffic to pass if it is accumulating, but this rarely ever happens. I keep close records and have determined that 58 MPH gets me the best mileage. I also will not take my rig down a 6% grade or steeper at 60-70 MPH. It isn't safe.

bsmeaton · 08-02-2008, 08:03 PM

I guess I thought exceeding the "safe" limit went without saying, but maybe not to some. I really didn't mean lock the cruise control to 75mph down Loveland Pass because that's what the sign says. Besides, the factory tires themselves have a 65mph rating that is unsafe to exceed.

I just don't believe in reducing speed on a 2-lane highway for the sole purpose of squeezing pennies out of a 10mpg vehicle, expecially when it means impositioning the drivers behind me so that I can save a few bucks. It puts them in a position to be in a continous passing effort, often taking risks that expose both them and myself.

I don't buy the pullover thing either. Rolling that rig to a stop on an unmaintained shoulder or emergency lane, then merging it back into traffic not only consumes any of the fuel you just saved, but also puts you and everybody else on the road at an unecessary risk.

We all share the road and should be good stewards. There are other ways to sqeeze a penny or two.

richfaa · 08-03-2008, 03:44 AM

It is not necessarily the increase in fuel mileage although it can be significant.We do not feel comfortable driving this rig, 22K plus, at high speeds.In Texas the speed limit of 80MPh was , to me, completely unsafe. Other states are 70/ 75..that is also too fast. It is not our driving capabilities we have no problem driving the Honda at those speeds but rather the capabilities of the camper.We do not think they were designed for those speeds or are safe at those speeds. We drive almost entirely on interstate type hiways and that far right lane is for...slower traffic.On 2 lane roads the speed limit is usually lower anyhow. 63/65 was our preferred speed.... now it is 60. We also believe that pulling over on a two lane road is not the safest thing to do and don't think you would have to do that under normal circumstances. The reson we felt ok about dropping to 60MPh is because we have noticed , in the several states we have traveled in this summer, that the traffic is moving slower.

Wiarton William · 08-03-2008, 03:48 AM

The point is......is it hard on my truck to let it(or make it) LUG and work hard in order to take e down the road....if it works hard at the lower speeds does my mileage sufffer... due to the harder tow?????

richfaa · 08-03-2008, 05:02 AM

logic would indicate that if the motor has to work harder it will use more fuel. This 08 Ford 6.4L does not lug or appear to work harder at 60 Vs 63/65 under normanl conditions. In fact all the numbers, EGT, RPM, etc are lower which would indicate the motor is not working as hard. Of course the proof is in the MPG numbers at various speeds. We get better MPG at 55MPH than 60MPH but we feel that 55 is to slow on the interstates. At 60 in the right lane we are pretty much moving with the big truck traffic which now days appears to be moving at 60/62mpg.( i will bet not in Texas)

bsmeaton · 08-03-2008, 05:33 AM

Don, if your 2006 has the automatic transmission, I don't think it can lug, at least not kind of lug you experience with a standard transmission or even the older Ford automatic transmission. Mine just seems to slip into any number of gears it needs to be comfortable for the speed.

With that, I think the only way to really tell if lower speeds reverse efficiency is to observe it on a pyrometer. Some folks have installed them, wonder what they have experienced.

Waynem · 08-03-2008, 06:39 AM

I'm not going to let a few 10ths of a mile per gallon interfere with my trip taking.

Yes, Texas truckers, for the most part are staying below 65 MPH. Now in their case, at 4-5 mpg, it probably helps them, but time IS money to them.

Be VERY CAREFUL when pulling to the side of a road whether on 2 lanes or Interstate. All the debris gets blown to the shoulder of highways. That includes any hazards like nails and other sharp objects. You take a chance of puncturing a tire on the TV or trailer when you pull to the side of the road. And, it's really not safe.

richfaa · 08-03-2008, 07:25 AM

Both of us being retired we have the luxury of never being in a hurry. This truck will be 1 year old the end of Aug and is now pushing 14K miles 85% of which is yanking the 3400 anchor down the road so a few tenths of a mile of improved MPG can be significant. We do have the aeroforce guage installed http://www.aeroforcetech.com/ and can read every parameters as well as pre turbo EGT temps.

The numbers tell the story and we are on instruments all the time. We know the parameters of the truck and keep within them for the best efficiency and 70/75/80 does not hack it. Some folks will say.....drive it like you stole it...well we drive it like we own it.

Broome101 · 08-03-2008, 08:02 AM

Todays diesels are made to work and work hard, the harder you work them the better they will perform in the long run. If you don't open it up ever know and them you will experience injector issues down the road. I know some will disagree but this is just my opinion, having owed 3 of them know this has been my experience with them. I usually run with the flow of traffic anywhere from 60-75 depending upon where I am at and what the speed limits are for the area. I have yet to ever feel this rig lug yet, not sure i will unless something breaks, it's a towing beast.
I am not recommending anyone driving faster than they feel safe in doing so, that is up to you to determine, good traveling friend with us always takes hour to 2 hours longer to get to same location when leaving at the same time from same neighborhood. He stops checks his tire temp ever so often and never goes about 60 MPH, but thats him he can do as he pleases, but cost him more to get to same location with all the stop and going.

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