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Author Topic: could this really be?  (Read 2665 times)
Blacksheep
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« on: September 14, 2008, 02:10:57 PM »

We fueled up to the top a couple weeks ago and went to Disney, back home, then went to Salt Springs and back home. A total of 561 miles. We fueled up at the same place right by our home and it took 60 gals. Now according to my calculations, that's 9.35 mpg.
I ran an average 60-65 mph and I don't think I ever went over 1800 rpm.
Does this sound right? If so, I'm pretty happy with that!

Ace
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gumpy
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« Reply #1 on: September 14, 2008, 02:13:40 PM »

What engine?  I thought you had a 8V71 in your bus?

You might get that with a 4 stroke, but I seriously doubt you'll get that kind of mileage with a 2 stroke. I'd expece more like 6.5 - 7 at those speeds and RPMs on a 2 stroke.

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Craig Shepard
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« Reply #2 on: September 14, 2008, 02:19:19 PM »

I think Craig meant 8V92 Wink
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Paul Hastings
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cody
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« Reply #3 on: September 14, 2008, 02:19:38 PM »

Thats great Ace, I had a simular thing happen to me, on the run back up north from Bk's place, my MPG were into area's they had never been before, I don't know how to explain it either.
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Blacksheep
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« Reply #4 on: September 14, 2008, 02:25:39 PM »

Craig its a 8v92 with a 740 allison and a DDEC.

Ace
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gyrocrasher
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« Reply #5 on: September 14, 2008, 02:30:06 PM »

Well, I have seen an 80K# semi do that with a very strong tailwind.(in dash fuel computer) Of course that's a 4 stroke cummins.
« Last Edit: September 14, 2008, 02:32:47 PM by gyrocrasher » Logged
makemineatwostroke
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« Reply #6 on: September 14, 2008, 02:42:10 PM »

BS; read your DD manual it will tell you what the bare engine will burn in pounds  per hr most 8v92 use 36 to 40 pound per hr at 1400 to 1800 rpm then add the weight, tire size and axle ratio and you are going to be around 50# + per hr that figure is good milage for a 8v92 in a 40,000 bus. have a great day
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Lin
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« Reply #7 on: September 14, 2008, 02:57:18 PM »

Twostroke,
     At about 7 pounds/gal, it would be just over 7 gallons/hour.  That would make it about 9 mpg at 65 mph (less if going slower).  So would it be possible?
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« Reply #8 on: September 14, 2008, 03:05:09 PM »

On our last trip to Pa, we did a lot of backroads and small town and got aroun 8..On our way home we did straight thruway and got 5..
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John P, Lewiston NY   1987 MC 9 ...ex NJT
makemineatwostroke
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« Reply #9 on: September 14, 2008, 03:11:14 PM »

Lin: if he has a 8V92 engine in the 450 hp range with no wind flat ground he can do it.I had a DDEC 8V92 in my Eagle that would get the same fuel mileage as the s60 in it now.The rpms he turning sounds like he has a 3:36 gear.   have a great afternoon
« Last Edit: September 14, 2008, 03:16:34 PM by makemineatwostroke » Logged
Sojourner
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« Reply #10 on: September 14, 2008, 03:23:37 PM »

Ace...was it filled to filler opening tank fuel at ambience's temperature with coach parked so that it tilt with filler side is higher than opposite side? I don't know how many gallon and if tank is layout so that tank long end is in coach side to side?

After long running or traveling, the fuel will expand some what due to hot fuel return.  So after the filling up it will take more fuel when fuel cool down. It may be not enough to make any big difference. It all depend how fuel in tank before fill up.

The thermal expansion coefficient of Diesel is 0.00046/* F. Assuming constant atmospheric conditions,

Right now when fuel tank cooled, refill again to see how more more. Then add it to 60 gallons figure.

Or...Next time after traveling, record fuel temperature in tank or return line with IR gun and then fill up. Again after over night cool off, refill to the top.

FWIW

Sojourn for Christ, Gerald
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« Reply #11 on: September 14, 2008, 03:40:19 PM »

BS; read your DD manual it will tell you what the bare engine will burn in pounds  per hr most 8v92 use 36 to 40 pound per hr at 1400 to 1800 rpm then add the weight, tire size and axle ratio and you are going to be around 50# + per hr that figure is good milage for a 8v92 in a 40,000 bus. have a great day

I thought engines were rated in lbs/hp/hr?  Your figures would be right on with a decimal point in front.
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makemineatwostroke
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« Reply #12 on: September 14, 2008, 03:46:34 PM »

sorry about that Q500 playing with a grandchild at the same time as posting
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TomCat
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« Reply #13 on: September 14, 2008, 03:55:28 PM »

Ace...was it filled to filler opening tank fuel at ambience's temperature with coach parked so that it tilt with filler side is higher than opposite side? I don't know how many gallon and if tank is layout so that tank long end is in coach side to side?

After long running or traveling, the fuel will expand some what due to hot fuel return.  So after the filling up it will take more fuel when fuel cool down. It may be not enough to make any big difference. It all depend how fuel in tank before fill up.

The thermal expansion coefficient of Diesel is 0.00046/* F. Assuming constant atmospheric conditions,

Right now when fuel tank cooled, refill again to see how more more. Then add it to 60 gallons figure.
Or...Next time after traveling, record fuel temperature in tank or return line with IR gun and then fill up. Again after over night cool off, refill to the top.

FWIW

Sojourn for Christ, Gerald

If his fuel/fuel tank was hot both times he topped off his tank, I can't see how this would be a factor.

Did I miss something?

Jay
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« Reply #14 on: September 14, 2008, 04:09:07 PM »

I would say that 7.35 is probably a more typical MPG for a bus like Ace's.  That would be around 20 gallons more fuel.  I doubt even hot versus cold fuel tank could explain that much extra fuel. 

My fuel tank is just a big rectangular tank like on a semi.  I don't have a long filler per se like some of the buses.  I just unscrew the cap and the top of the tank is three or four inches below where the cap screws on.  I can get pretty close to the same amount in as long as the station is reasonably level which most are.  The local station I frequent leans about 5 to 10 degrees away from the pump so my fill isn't always the same.
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Brian Elfert - 1995 Dina Viaggio 1000 Series 60/B500 - 75% done but usable - Minneapolis, MN
Blacksheep
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« Reply #15 on: September 14, 2008, 04:39:51 PM »

Aww gee fella's, I made a mistake!!!
When I posted I stated 60 gals., but as I was reading your postings to Susan, she corrected me. She's the one that keeps the books/records. She said it was actually 59 gals..
Now doing the math and reading what you all had to say, I feel like it went the wrong way. I was actually hoping to be closer to what you all said it should be. All I know is the roads are really flat and boh tiomes there was little to no wind but I did forget to mention I was pulling a very small trailer with a golf cart!
I can't explain it so as long as the bus is running as good as it is, I really could care less if its 5mpg or 10mpg. If I couldn't afford it and had to worry about it I would have never got involved in this hobby! 1, 2, or 3 mpg is not going to make me or break me!
Ace
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« Reply #16 on: September 14, 2008, 05:25:38 PM »

 It really could be!!!!  I was getting the  same milage Ace. What I found was the return fuel line to the tank was partially blocked. It would only leak under high pressure or at highway speeds. There was a loose couplng that fuel could be forced through. Darnest thing it sprayed it on the highway at highway speeds and did not leak at low speed so I never saw the leak!!
 Better look for something like that, I dont know how you can afford to drive a bus with that kind of milage!!  HTH Jim
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« Reply #17 on: September 14, 2008, 06:39:16 PM »

did i misread something or was jjr just pulling bs's leg.  i'd be ecstatic with 9.35.  freeway home from valdosta to cinci, used 96 gal and got 7.1.  i thought that was great for 8v92 pulling an express van full of stuff.

Ace, you've had way too much posting lately.  is Susan still with you?  you're spending a lot of time on pushing the wrong buttons on this bullitin board.  Cheesy Cheesy
« Last Edit: September 14, 2008, 06:41:10 PM by manasst » Logged

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« Reply #18 on: September 14, 2008, 06:48:25 PM »

Example if in the ground tank of diesel fuel is 40F cooler than above ground tank (100F)

. The thermal expansion coefficient of Diesel is 0.00046/* F. Assuming constant atmospheric conditions.

So .00046 X 40F = .0184 gal X 200 gallon = 3.68 gallons gains using cooler fuel.

So which will give more for your money?  Cold fuel. In other words, for every 54.35 gallon of colder (40F) fuel, you gain one gallon

Or, in Ace case. If you pump in 54.4 gal @100F fuel in tank and after shut down to soak up the cool over night temperature of 60F, you lose 1 gallon in the morning.

It about expansion and contraction in large quantity.

The bottom-linenever buy very warm or hot fuel before the next morning. But fill up in the morning or go some where they have cool fuel.

For every gallon you gain, multiply that times mpg = XX number of more mile for the money.

Some pump has build in temperature compensator, so it wont matter what fuel temperature for the dollar.

FWIW
Sojourn for Christ, Gerald
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« Reply #19 on: September 14, 2008, 07:16:04 PM »

My understanding is that almost no gas pump in the USA has temperature compensation.  I also understand temperature compensation is somewhat common in Canada due to the colder weather.

It has been explained that temperature compensation in the USA would make very little difference in fuel quantity delivered.  The tanks are underground and the ground stays at a relatively constant temperature year round.  This is how geothermal heating/cooling works. 

Some stations have been accused of heating fuel to cheat customers, but others have explained that the amount of energy required would negate any extra revenue.
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Brian Elfert - 1995 Dina Viaggio 1000 Series 60/B500 - 75% done but usable - Minneapolis, MN
JackConrad
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« Reply #20 on: September 15, 2008, 05:49:57 AM »

I don't know if it makes much difference, but I have seen several tankers sitting in the sun at Flying J dumping into the underground tanks as we were filling our coach, along with several truckers.  Jack
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« Reply #21 on: September 15, 2008, 08:15:53 AM »

Thank Jack...You said it better and added thought to our bus nuts to be aware that you can save few dollars.

Keep IR gun near by in a handy place...you be amazes what we miss for the pass knowledge you have had.

Have fun with IR gun!

FWIW

Sojourn for Christ, Gerald
BTW...IR gun check tanker temp...next time you are there. If they ask...tell them "I am learning about temperature"
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Ps 28 Blessed be the LORD, because he hath heard the voice of my supplications. The LORD is my strength and my shield; my heart trusted in him, and I am helped: therefore my heart greatly rejoiceth; and with my song will I praise him
luvrbus
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« Reply #22 on: September 15, 2008, 09:10:51 AM »

More than likely just a one time deal I have had those spikes in mileage over the years but I would not plan a trip with a 8V92  based on 9 miles per gal when you get a 2 mile per gallon spike it will be different the next tank is for me anyway brings me back down to reality .        good luck
« Last Edit: September 15, 2008, 09:19:10 AM by luvrbus » Logged
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« Reply #23 on: September 15, 2008, 10:18:10 AM »

You should track your mileage as an ongoing process.

I would expect your next fill-up will be disappointing relative to this fill.

Ed Roelle
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Blacksheep
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« Reply #24 on: September 15, 2008, 10:33:02 AM »

I guess I could hook up my prolink and see what it says! Would you think that it is accurate?
Ace
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« Reply #25 on: September 15, 2008, 06:08:39 PM »

Canada has had laws requiring temperature compensation for the fuel pumps for many years.

The American consumer is being ripped off, cents at a time, or in a busnut's case, dollars at a time.

I continue to be surprised that this theft goes uncontested.

happy coaching!
buswarrior

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« Reply #26 on: September 15, 2008, 07:14:54 PM »

It's a conspiracy!

& since they are shafting us at each fillup, heck, we're all getting better mileage than we thought!

 Grin  Grin  Grin
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