Best fuel economy so far!

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Best fuel economy so far!

March 27, 2017, 08:22:44 pm

Okay, the first fuel fill after the new engine was terrible (<3 mpg), but then the generator ran nonstop for 10 days. The next one was just over 7 mpg, as were the next couple. Today's run was well over 8 mpg! I've never gotten that good in the four years we've had the coach. Tomorrow we make the final drive to Stockton SP, about 250 miles. I'm anxious to see what I get on that trip.

Even better, the oil level is still showing full and there are NO drips under the engine. So far things are looking good.

Re: Best fuel economy so far!

Reply #1 – March 28, 2017, 05:07:09 am

We not to burst your bubble Or steel your thunder but the DW is MUCH more comfortable when we are just motoring down the road at 55 ish ( love California truck speed limits). So lately I've been just enjoying the country and motoring along at well 56.

Would drive a lot of people nuts but I'm good with it. Tank before last was 12 mpg conservitely, with generator accounted for. Wow, the 8.3 will do good. The cummins seminar guy said to find your sweet spot were the Allison shifts to 6th and it seems to work. When I get into town and stop and go kicks in, all bets are off.

Re: Best fuel economy so far!

Reply #2 – March 28, 2017, 12:54:08 pm

55 is a great speed for sightseeing with the added benefit of much better fuel mileage. Since we usually prefer the secondary two lane roads on cross country trips, it's easier to relax and enjoy the scenery without the urge to keep up with traffic. Heading slightly downhill from our Sierras to San Francisco, keeping the speed to 55 does net us 12 mpg. Following Highway 1 from Monterey south next to the ocean, we are lucky to get 5 mpg.

David: good for you! You should see almost zero drips unless something is wrong. 8+ mpg long term overall is about right for combination of mountains and plains with toad.

Pierce

Re: Best fuel economy so far!

Reply #3 – March 28, 2017, 10:20:22 pm

Looks like I crowed too soon. Only about 4.5 today. Of course, almost all of it was going up and down (mostly up). We traveled from near Little Rock to Stockton, MO today, so all of it was in the Ozarks.

Re: Best fuel economy so far!

Reply #4 – March 29, 2017, 12:28:08 am

We just finished a 2,500 mile trip to AZ. We went out on the Southern route, via I-20 and I-10. Decided we already had more of El Paso than we ever wanted. Came back on the middle route via I-40. Ran into sleet/snow/rain in Albuquerque, In Amarillo, we had heavy winds that ripped the door out DW's hands ($125 for a mobile mechanic to remove the Pos A Loc lever so we could close the door and continue our trip). Took the turnpike North of OKC, which totally avoided I-35 (and most of OKC); it was my best route through OKC ever!

Mileage for the trip was 7.0 mpg (measured by fuel input and mileages). We were towing a KarKaddy with a Town and Country minivan, averaging 65-70 mph (where we could). On other trips without the toad, and speed at 65 or less, we averaged about 8 mpg. Guess 1 mpg is worthwhile for bringing the toad.

Trent

Re: Best fuel economy so far!

Reply #5 – March 29, 2017, 07:08:05 am

My 91 with the 6V92TA has averaged 8.3 using the gallons to mile math and ECM showed 8.4 mpg average on it over about 68,000 miles.
I am thinking of putting on a Aero Resonator in place of the muffler curious to see if any mileage would increase.

Re: Best fuel economy so far!

Reply #6 – March 29, 2017, 08:20:26 am

Four lane highways make 55 easier. Two lanes I get trucks constantly coming up on me. So I go faster.

The fan controller mods, the resonator, low rolling resistance tires, rebuilt alternator, fuel filter system replacement, solar, Donaldson BlueTec air filter, motor tune up and sensor replacement and a cetane raising fuel additive have together raised my MPG enough I can go ten miles per hour faster and get better mpg than I did before the service and mods.

Frugal and not type A people would probably enjoy the money saved as in ideal conditions and 60 mph the coach exceeds 11 mpg.

I can't drive 55 to quote an old song.

Historical average in our coaches computer was 7.7. Almost for sure at 60-65.

I am at 8.3 mpg at 70 towing 3,600....

Much better, IMO

Re: Best fuel economy so far!

Reply #7 – March 29, 2017, 08:38:06 am

I have gotten 8mpg but never better. 40 ft with 400 towing is a lot of weight. Average about 7.4 . Be leaving end of April for Missouri. Changed tow from GMC Terrain to Buick Enclave. Ready to tow but no experience with this one. M & G put in a battery disconnect so have to reset clocks every use. Love to travel in the Foretavel.

Re: Best fuel economy so far!

Reply #8 – March 29, 2017, 09:11:42 am

EXTREMELY difficult to fill the tank to exactly the same level each time, so really not worth trying to calculate fuel mileage on a single tank, particularly if only a half tank or so. Even one or two degrees difference at the pavement where you fill can make many gallons of difference.

While we record every gallon that goes in, I only calculate MPG as a whole trip.

Basing conclusions on a single tank can make you crazy chasing the "what happened's".

Re: Best fuel economy so far!

Reply #9 – March 29, 2017, 10:51:57 am

Yes, getting accurate measurements can be difficult. Using the airbags to drop the port side and then filling to the neck did it on our U300 with exactly 6 gal/inch. Others may have a different tank arrangement. Now I just use the Pro-Link for any distance. Should work for any electronic engine if you have a reader.

Pierce

Re: Best fuel economy so far!

Reply #10 – March 29, 2017, 01:06:55 pm

Personally I never bother with the MPG till the end of trip as Brett said, and then only for something to do. Add up fuel cost/gallons used and try to figure how many MPG (but really does not matter), then I throw the paper away. Just getting there safe is what counts.
JohnH

Re: Best fuel economy so far!

Reply #11 – March 29, 2017, 01:27:43 pm

MPG does not mean much to me anymore. It's been my experience that no matter what I do I can never match the MPG's that a lot of folks claim; and with the same equipment and that holds true for everything I have ever owned from a Volkswagen Beetle to my class A tractor. When my tank is half full I fill it. My fuel costs don't equal the property taxes we use to pay so I'm good.

Roland

Re: Best fuel economy so far!

Reply #12 – March 29, 2017, 02:14:34 pm

Yes, I know that calculating mpg by the tank is NOT realistic. Has to be figured over several tanks if to get even close.

Lately I've been trying to figure it in the reverse if I have to prepay to fuel up. If I've gone X amount of miles and get about Y for mileage, then I should need about = this much cash. Works OK until i get 6.5 mpg or ? And then I have to go back in and pay yet again Jrucbemsifb !!

I think I miss at least that part of an electronic engine.

Re: Best fuel economy so far!

Reply #13 – March 29, 2017, 02:38:30 pm

For those without an electronic engine, if your HWH leveling is accurate, you can use the "dip the tank method" on many coaches. To check the HWH, just use a level on the coach or the top or sides of the fuel tank. Dipping ours comes out very close to the Pro-Link 9000. DROP THE DRIVER'S SIDE, fuel, drive any distance, accurately level the coach and dip the tank. Using 6 gal/inch, I can come out within a gallon or so compared to the Pro-Link. The longer between fueling and measuring, the more accurate the results will be.

If you can't precisely level the coach, your results will be inaccurate and frustrating.

Pierce

Re: Best fuel economy so far!

Reply #14 – March 29, 2017, 09:54:22 pm

4000 miles round trip south and back. 3126 Cat engine, 61 -62 mph or 1750 RPM's is the sweet spot. Towing a 02 wrangler 4x4........7.0, sometimes better, sometimes worse, all according to the Silverleaf, it's history archives, and my pocket book!
Cheers
P.S. 78-79 MPH net 5.0-5.5 MPG, but didn't enjoy the ride

Re: Best fuel economy so far!

Reply #15 – March 29, 2017, 10:00:31 pm

I keep a spreadsheet of fuel use, and the final column is overall average. It will take some time for that number to start coming up, but it should start going up in May when we start doing long-distance moves again.

Re: Best fuel economy so far!

Reply #16 – March 29, 2017, 10:14:30 pm

Like Roland I don't worry about fuel mileage, other than figuring my fuel stops and VMspec takes care of that.

Re: Best fuel economy so far!

Reply #17 – March 29, 2017, 10:51:25 pm

If you fill your tank to exactly the bottom of the filler neck, then use most of the 150 gallon tank, then refill the tank to the exact same spot on the filler neck you will get accurate fuel efficiency readings. It's very repeatable. I've done this all across the country and I get almost the same exact mileage tank after tank. The highest I've ever gotten is 10 miles per gallon and that's at 60 miles per hour. Driving slower only makes the transmission shift more without any increase in fuel efficiency. I've put 50,000 miles on my coach over the past 5 years and I check my fuel efficiency every time. If you only use a small amount of fuel or you don't fill to exactly the same point it won't work as well initially, but will still work out accurately over time. I can even get reasonably accurate fuel efficiency using this method on my tiny motorcycle gas tanks. The motorcycles only vary by about 5 mpg each time, which isn't much for a motorcycle. My cars all varied by about 1 mpg each time using this method constantly over a 30 year period and keeping a log book each time. My coach has a much larger fuel tank and only varies by a fraction of a mpg from one fillup to the next. The lowest fuel efficiency I've ever gotten was about 7.5 mpg when I ran the genset a lot. Overall the fuel efficiency for the coach is much higher than a car or a motorcycle when you consider the amount of weight and wind resistance. You definitely don't need an expensive computer to keep track of your fuel efficiency. Use the tank method every time, keep a log, and the very small error(s) will even out over time. It has to work if you think about it. All you're keeping track of is the miles you drove and the gallons you put in. If you screw it up a hundred times by filling up to a different level each time it'll still even out overall as long as you wrote down the correct miles and the correct gallons and did the arithmetic correctly... but if you need an excuse to purchase an expensive new toy go for it

Re: Best fuel economy so far!

Reply #18 – March 29, 2017, 11:07:11 pm

also, level the coach before you fill. Just takes a second. check your level point with an LED flashlight.

Re: Best fuel economy so far!

Reply #19 – March 29, 2017, 11:48:44 pm

You can tske a cell photo of the gen hour meter, subtract .44 gph in my case. Aqua hot does not yet have an hour meter.

The m11 we have goes into sixth at 55 at medium throttle.

3.91 rear gear. The resonator REALLY added to the low rpm torque.

Re: Best fuel economy so far!

Reply #20 – March 30, 2017, 01:58:39 am

Ok.
In trying to understand the tilting the coach thing for fueling. You lean it over to drivers side cause our filler neck is on the passenger side ?
Then fuel it completely to the filler neck, so as to get all the air out and completely full of fuel.

Would you not get the same full gallons in it every time. Our case would be 140.

And the big ( dumb ? ) question is, Is it ok to drive around with a stuffed diesel tank.

Re: Best fuel economy so far!

Reply #21 – April 01, 2017, 04:55:34 pm

We always get around 7.3-7.5mpg. We do 63mph or so (just into 6th gear). We are always towing either a 5000lb lexus GX470 or a 7000 pound (or so) trailer. To me, this is very good when you consider we almost always travel with 150+ gallons of water, and all of our stuff in a 42' tag axle rig. Certainly impressive compared to our dually truck camper struggling to hit 12mpg. That number is not compensated for generator or aquahot usage, which one or both are usually on when travelling.

Re: Best fuel economy so far!

Reply #22 – April 02, 2017, 08:36:57 am

Here is my simple thought on fuel consumption. My hotrod and corvette days were filled with how many miles a gallon does that car get. My reply would be if thats a concern dont own one. These are are well built beautiful coaches. We can brag about lots of things besides fuel usage although I'm probably a minority on this one. Drive careful at any speed and enjoy the view.

Re: Best fuel economy so far!

Reply #23 – April 02, 2017, 09:36:23 am

Had a Dodge 3/4 ton power wagon with V8, auto, 4WD. I put an 8 1/2 foot overhead camper on it, and going into the wind in CO I would feel great if I got 8 mpg. Even though I was dirt poor, it was worth the cost for the places that old wagon got me to and from.
Compared to that I am driving a U270 Prius!

Len

Re: Best fuel economy so far!

Reply #24 – April 02, 2017, 10:09:02 am

My 380 lb motorcycle is supposed to get over 50 mpg. My right hand keeps it below 30 mpg tops, but I'm getting 60 smiles per gallon. And you will have to pry the grin off of my face. My 71 F150 with a 360 only gets 10 mpg and it doesn't matter if it's in the city or on the highway, or unloaded or pulling a 26' boat. Always the same and no air conditioning. Guy at the performance shop agreed as they used to have one for parts delivery, he said they tried different cams, intakes, carbs and headers with same results. they finally swapped the crank and rods to make it a 390 and then got 15 MPG.

If coach can get 8 mpg I will be happy with the convenience it offer's.

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