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Author Topic: could this really be?  (Read 2736 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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paulcjhastings
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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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quantum500
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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
87 SaftLiner
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belfert
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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
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