gallons per inch

rcbeam · September 23, 2012, 03:42:06 PM

I think I have read this someone in a post before but can't find any reference to it now. I have an MC8 with the factory aux fuel tank. Data plate on the fuel door says 179Gals, and to not put more than 170 gallons in tanks due to federal law. I am trying to figure out what the 170 gallon fuel level would be in the tank and how many gallons per inch that would be.

I have a special heavy wire that I use to 'dip' my tank so see how much fuel I have... not very accurate but all I have right now and I can't get a handle on mileage yet. I haven't had any big trips. I take her out ever 3-4 weeks though on a Sunday for a drive down the interstate and back... usually 60-80 miles round trip.

Anyone else been through this?

Tx,
Russell

luvrbus · September 23, 2012, 03:54:37 PM

Post the tank size for us no way anyone could answer without dimensions of the tank use 1 gal = 231 cubic inches not very hard to come up with gals per inches then or do it in cubic feet 7.48 gal per cubic ft

good luck

Utahclaimjumper · September 23, 2012, 05:30:46 PM

So how is anyone going to know what you have in your tank at any given moment???>>>Dan

Ed Hackenbruch · September 23, 2012, 05:36:07 PM

If you run it down to the 9 gallon level you are probably going to be stranded along side of the road somewhere.

I have a 144 gal tank and the most i have ever put in at one time is 110 gallons. I usually plan to fill up after i go 700 miles, i average just over 7 miles a gallon so that puts me right at 100 gallons or less each time i pull in for fuel.

PP · September 23, 2012, 06:23:45 PM

Our Prevost has the 205 gal tank and measures 24" high to bottom of neck. It takes 8.5gal/inch. The fuel gauge never goes above 3/4 or below 1/4 so I keep a 1/2" wood dowel handy and have found that it works pretty slick for checking MPG also just by measuring the fuel level on the stick and calculating fuel consumed. If your tank stretches from one side to the other (I have a filler neck on either side of the bus) the dimensions are probably fairly close to mine. Will

luvrbus · September 23, 2012, 06:53:12 PM

Isn't the factory aux tank on a MCI in the front bay of the bus I don't think he is speaking of the main tank if I am not mistaken he carry's over 300 gals of useable fuel

good luck

daveola · September 23, 2012, 07:29:42 PM

Before filling, figure out how many inches it is at full with the "dip" wire (make sure it touches bottom and doesn't bend), and then add 50 gallons, and measure again.

Take the difference in inches, then (50/difference) is your gallons/inch.

You can do more/less than 50, of course, but too few gallons will make the calculation more error prone.

challenger440 · September 23, 2012, 07:33:06 PM

Main tank on my 7 is 144 gallons. 179 with auxilary. How they could ever measure you had more than 170 on board is beyond me. If in doubt ask if you could drive around the block! j m

Boomer · September 23, 2012, 07:36:13 PM

144 main plus 35 in the aux tank in the front bay for 179 total. They cross feed. The main will have a sender plate, why not add a fuel guage?

luvrbus · September 23, 2012, 07:40:37 PM

The 8 in Mohave has a 180 tank in the front bay I thought it was a big aux tank compared to a Eagle

Scott & Heather · September 23, 2012, 08:14:22 PM

Ditto what boomer said. Our 9 has the same setup. Like the extra cap but hate losing the bay space. Of course we added another 100 gal aux tank up there. So we have 279 gal cap. We hate the space hog more than we hate stopping for fuel so we are planning on removing it.

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buswarrior · September 24, 2012, 06:24:48 AM

The fuel tanks in these vintage MCI require a bit of trickery to get your dipstick properly calibrated.

The tank is taller at the fuel door end, and then it gets shorter to pass under the utility channel.

Once the fuel level is out of the bump up, you will get consistent readings, as the aux tank is a constant shape, and as noted, the two tanks are tied together with open connections.

Beware that the fuel migrates according to the level of the coach, so nose up or down will change your readings.

I know of a small town in Quebec down in the valley, with roads very steep out of town. No doubt others like it in the hill country in other parts of the continent. An aux tank equipped coach will run out of fuel climbing out of town if the tank is getting towards the 1/4 tank, due to the fuel running back into the aux from the main, and leaving the fuel pick-up in the air. Discovered by a first line coach company back in the MC9 days, who preferred that the drivers not purchase the expensive fuel in La Belle Province... needless to say, after blaming the driver for the 3rd time... drivers were authorized to purchase a suitably small amount of fuel in order to get the tank up a bit to prevent the service delivery failure.

As for the Federal Law notation on the tanks about their capacity and their usable capacity, it was, and still is, affixed to the tanks by way of the legislation that requires that fuel tanks have some room for expansion in them. The filler neck takes care of these matters, unless you turn the coach on its side, you can't get more than the noted fuel into them. So, somewhat of a moot point.

Similar legal requirement to that "Objects appear closer" sticker on all of our auto right hand side mirror.
We know, but they legislated that it has to be printed on there.

happy coaching!
buswarrior

Scott & Heather · September 24, 2012, 06:38:51 AM

Can you imagine being pulled over by DOT, they inspect the tank fuel level..and tell you, "Sir you have 9 gallons too much fuel allowed by Federal law, please drive off the road into that parking lot up there so we can handle the paperwork for your ticket" so you drive a block in first gear (scream Detroit, scream!) and into the parking lot...ask him to check the level just one more time for your sanity, so he does..."Sir, I guess I was wrong, you're right at 170 gallons, sorry to waste your time"

lostagain · September 24, 2012, 06:45:18 AM

All this seems like a lot of fussing for nothing.

Just fill it up and drive.

JC

rcbeam · September 24, 2012, 08:51:33 AM

Thank you to everyone that has posted a reply so far to my question. To respond indirectly to a few, I could just "fill it up and drive" but that does not answer my question. As for tank dimensions I have no clue. All I can say is I have a MC8 with the stock main and auxiliary tank. The tanks are still hooked together. I was just hoping that someone had already figured how many gallons of fuel the two tanks hold per inch of fuel when measured with a dip wire at the filler of the main tank.

At this point I have no idea what my fuel mileage is and I would like to begin to get a handle on that for planning purposes. The bus starts easily, does not smoke at all, and runs great. Having mileage in line with norms would just further indicate that the engine and drive train is in fact running properly. Knowing somewhat what my mileage is would help in planning costs for future trips.