Gas Mileage, Tune-up?, Real Numbers

[wg4t50]

Ya just gotta laugh  sometimes     

[belfert]

I would be ecstatic with even 10 MPG at 65 MPH!  Generally I have been right around or just above 8 MPG with no trailer at 65 MPH.

My MPG does seem to have been trending down in the last year or two.  I believe we got around 7 MPG on our last trip out west.  We have upgraded to a larger trailer and seem to keep adding more and more weight.  The difference between 7 and 8 MPG is 71 gallons on a 4,000 mile trip.  $300 won't bankrupt me, but fuel is far and away the #1 expense for my bus trips.

I'm right now looking at buying a used commercial party/event tent, but I wonder if I really want to add 200 or 300 pounds to my trailer and bus.

[robertglines1]

brian are you runnin 12 or 11  60 series?

[luvrbus]

Most 60 series are in the 6 to 8 mpg range I have heard of few doing a little better but it is only hear say every bus I have ever checked with a ProLink with series 60 are around 6 in the 45 ft tour buses some even 5 the difference is they run the speed limit and not out for bragging rights on what great fuel mileage they get like the bus nuts. lol
The 500 hp ISM in the 45ft S&S jobs are 5 and 6 mpg at highway speed limits no free lunches with a modern 4 stroke engine when it comes to fuel the old 8v92 tuned right will do the same or better

good luck

[robertglines1]

Just fishing: 10 would be a dream  7 great  5 no better than what I have now. Hoping for 7 with the 10speed and 60 series. Will run speed limit.  Like I said just fishing proof will come soon enough.  it will be tested ..    Bob

[belfert]

I have an 11.1 Series 60.  I'm not looking for bragging rights.  I drive 65 MPH to save money and be a bit safer.  I might drive faster if someone else was paying the fuel bill.

[Bus Busted]

   What is the best way to find MPG anyway? Is there a good way to read fuel used? Can't go by when the pump shuts off as a full point, as it could take another 40 gal after stopping. I would top it off and wait a bit, then hit it again until I see it just sitting at the back of the fill neck. I feel after 10 trips I should be within 2-3 MPG of true MPG (let me know if my thinking is off) Oh, and I didn't really start this to be a bragging / best bus mileage ever / pissing rights / post. I noticed different numbers than most stated and wanted to know what could be the cause. Also it should be know that there is a chance this bus is pulling air with fuel as seen in some of DemoDriver's posts when he owned this bus. (Plus the red switch mystery trans he also went into detail on) So I guess I'll just shut up and enjoy the mileage I do get as I have another trip coming up soon.

   Bob, not sure about stopping by on my way down to Nashville in January, but would make a trip to Evansville in the bus just to check out your buses and how they are setup (rope LED's and all).

   Thanks all for the input on this and if it gives you a laugh, then glad to have brightened your day. Jon

[artvonne]

Just fishing: 10 would be a dream  7 great  5 no better than what I have now. Hoping for 7 with the 10speed and 60 series. Will run speed limit.  Like I said just fishing proof will come soon enough.  it will be tested ..    Bob

  Just remember that RPM has as large, if not larger effect on fuel economy as does speed. If your RPM is so far under or over the sweet spot to blow engine efficiency down, driving faster where the engine is at optimal RPM may actually pull off better fuel mileage. Everything is a trade off/compromise.

  And we should all remember, what you could get for economy driving a particular vehicle has no real bearing on what another could get. Its not all about speed, a lot has to to do with how you work the throttle. Smooth and steady on the pedal gets the highest fuel economy. Constant power adjustments and constant changes in speed will totally blow any chance of good economy.

[Oonrahnjay]

What is the best way to find MPG anyway? Is there a good way to read fuel used? (snip)

     I did a lot of work testing vehicles back when I was a useful productive citizen.  Our rule was try to fill to exactly the same point (much easier with a car with smaller tanks and the possibility of filling to the car filler neck), try to run three tanks in similar conditions (road speed, hwy vs intown, load), and average those three.  An average of three is pretty accurate; if you change something (or if something changes like a leaky injector) you'll see it in the three tank average.  You'll also note that individual tanks can vary pretty widely.

     After it's calibrated, modern electronic measuring is pretty accurate, but that's a luxury most of us don't have.

    But the real answer is that it can be very difficult to get an accurate MPG on just one or two tanks.

[belfert]

My tank is just a long rectangle with a cap on either end.  There is no filler tube.  I can see the level of the fuel and I can fill to the same level every time.  I keep filling after the auto shutoff.  I also have a Silverleaf that reports exactly how much fuel the engine used.

On any one trip we might have four or five drivers.  It doesn't seem to really change MPG any as we all use cruise control.  Often the cruise set point is the same between drivers as the engine doesn't get shut off between drivers very often.

[robertglines1]

Jon: Come by anytime  Won't be Fla bound til Feb.  Mci8 tin tent few miles away. Hvac guy and a bus nut.  Mileage is a gift in this hobby.  Just a necessary evil we can all dream about getting better. Very possible your getting 10 would be great.  It's all in the science and driver. Looks like original set up was rite on.   happy bussin     Bob

[prevosman]

I record every gallon of fuel added to my coaches along with the location, price, and total cost.

My records go back to 1990. As a result I can come pretty close to calculating my mileage except for usage of the Webasto and the Generator. I have a reasonably accurate estimate of generator fuel usage based on 160 continuous hours and only 2 miles of driving between fill ups.

Anyway I averaged 5.6 MPG based on annual mileage calculations on my 8V92 powered coach, and I am 7.5 on my current Series 60 coach. My ProDriver agrees with my annual averages adjusted a little to compensate for Webasto and generator use. Basing an mileage calculation on a single fill up gives me such a wide spread from one to the next I lack confidence in individual calcualtions.

I have found the greatest impact on mileage is speed (or headwinds), hills (flat terrain is better), the weight of the toad, whether I run the Over the Road Air, and how much stop and go driving is involved.

[luvrbus]

Yea ,flat lands will yield better mileage but these 50,0000 lb coaches now days not much you can do about it except pay the price doesn't matter what engine you have running 75mph all day long you are not going to average 8 mpg.

My friends at Arrow say 5 to 6 loaded coming or going they never expect more from the Prevost with the Volvo D13 or series 60 in their Setras or the Cummins in the MCI pre EGR engine they do get a little better mpg

good luck

[Ericbsc]

 At the risk of being burned at the stake I am going to report my fuel mileage. I put a 12.7 series 60. Allison 6 speed double overdrive, and 4:11 rear. Running 24.5's. I have put about 2k miles on this setup so far. The first trip out 700 miles the silver leaf showed 10.7 running at 65 on the way to the BCM in TN. On the way back I bumped it to 70 mph and it fell to 10.2 mpg. Last trip to Charleston, SC around 650 miles, and a thousand trips around town working on the (CRUSE CONTROL) LOL 9.3 mpg average with a prolink. I expect if driven conservatively, average will be somewhere between 8-9 mpg.
    With my 8-71 Allison 654, and 3:73 I averaged between 5 and 7 mpg. Never got better than 7.5 best I could tell. !0-12 with a 6v92 seems way off, but if it is correct I would shoot the first person that layed a wrench on it!!!

[rv_safetyman]

Folks have mentioned all the big knobs - engine rpm, speed, wind, hills, weight, etc.  

Overall, I have averaged a bit over 7 MPG (as reported by my SilverLeaf) with the Series 60 and AutoShift (over 60K miles).  We live at 7500 feet, so I climb some pretty good hills no matter which way I go.  My Aqua-Hot and Generator are off a separate tank, so I could weigh through my record book and verify that number, but I think it is pretty close.

I had not given much thought to weight in the past.  Once you get the weight rolling, it becomes a lesser factor - except on the big hills.  What really got my attention was driving some two lane roads in IL/IN/OH a few times.  I figured driving 55-60 (set CC at 68 on the interstates) on relatively flat roads without huge winds, would really help .  Boy was I wrong.  All of the accelerating when leaving the small towns really hit the mileage.  I was in the 5 MPG range during those legs of the trips.  BTW, I am at about 46K with the close to 10K service truck.

A couple of years ago I did a lot of investigation about the affect of speed.  I did a bunch of running at 63 MPH and did not notice any difference - indeed, it looked to me like my mileage went down (engine RPM about 1380).  When I went back up to my normal 68 MPG (about 1490 RPM) my mileage seemed to improve slightly.  The 63 MPH trial was over several hundred miles on Interstate highway roads.  The only thing I did notice was that I did not have to pass Swift trucks  

So, the bottom line is that each of the factors listed above have impacts that are a function of the bus.  Some of the factors (knobs) can be tweaked to try to maximize mileage.  That said, there is not a lot we have control over in terms of making magical fuel mileage numbers.

Jim