View Poll Results: What kind of mileage do you get?
3-5 with Gas 12 3.16%
5-7 with Gas 36 9.47%
7-10 with Gas 38 10.00%
10+ with Gas 15 3.95%
3-5 with Diesel 2 0.53%
5-7 with Diesel 23 6.05%
7-10 with Diesel 137 36.05%
10+ with Diesel 117 30.79%
Voters: 380. You may not vote on this poll

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Old 08-28-2006, 11:06 AM   #21
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Join Date: Aug 2006
Location: Conyers, GA
Posts: 16
Well we just took our first trip (to Bristol, TN) and managed about 9.5 MPG with quite a few hills although we're still pretty empty inside. We we're unable to get an average for the entire trip since we broke an injector line and pumped out a BUNCH of deisel before we noticed and could get off the mountain we were on at the time. Side note: We miraculously found a replacement line in Johnson City and were back on the road in no time.

1985 International 28 Passenger
6.9L Diesel/Allison AT-545
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Old 08-28-2006, 07:03 PM   #22
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Location: Saint James, MN
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Isn't that a pain? I disconnected my veggie oil return line prior to leaving for one reason or another and never hooked it back up. Well this meant there was nothing holding up the slid down and the valve on the veggie oil side was popped open. I'm sure SOME fuel returned to the diesel tank at the time, but I KNOW a lot more just kind of pumped all over the engine compartment. Oh well...such is life. A piece of speaker wire did a darn find job holding the apparatus up and out of the way so it never happened again.
Skooling state at a time...
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Old 12-28-2006, 05:26 PM   #23
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Join Date: Oct 2005
Location: Wyoming & Indiana
Posts: 37
mileage,engine,gearing &gvwt?

I get 8-10 regardless of terrain. Usually closer to 8. I have dt466. It has 4:76 gear ratio. I never have my foot to the floor to maintain speed. once its up to speed I actually don't press it all that much, just enough to keep it pushing those low gear ratios. This is why I think 4:10 gears would be fine. I might get a steady 10 with an occasional plus or better(10-12), run quieter at 55 and get a top speed of 67mph at the same rpms 55mph is now. I would love opinions on this. In fact I may post a whole new forum on this for feedback. My GVWT 25,800. I actually weigh 19,500 with full fuel and 55 gal of water and all my belongings. I live in this thing.
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Old 12-29-2006, 02:53 AM   #24
Join Date: Sep 2006
Posts: 105
Year: 92
Coachwork: ward flat nose
Chassis: international
Engine: dt466 mt643 air ride
Rated Cap: 84
Hello JoeA, I too have the DT466, but mine is not aftercooled. I bought my bus 900+ miles from home and got 10mpg (actually 10.4 mpg) on that trip. The bus had all the seats in it and weighed 19.490, full of fuel. Mine has the MT643 trans and 4:44 axle ratio. I was running 60mph at 2260 rpm, on 295-75/22.5 tires.

I've talked to several owners and drivers of m/d trucks that are running this same engine and some have the auto trans, while others have the the 5 speed 1:1 high gear and most of these guys have the 4:10 axle ratio. Of the ones that run several states with this setup, they are not happy campers, when trying to average 65 mph. Now there trucks will hold 65mph, but the fuel mileage is better at 6o to 62 mph. And some of the ones that own their own are even talking about changing their axle ratios down to 3.7 and even 3.55 for faster cruising and less engine noise. Of course these trucks run over 2k miles a week so maybe they know whats what with these power trains. I'm taking the wait and see approach, I too would like to get a 65mph cruise speed down to less than 2000 rpm.
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Old 12-29-2006, 07:26 AM   #25
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Join Date: Nov 2003
Location: Whidbey Island, Washington (USA)
Posts: 465
Hey Joe,

Those numbers don't work out quite right; all the charts I found on the 245/75R22.5 tires say they're 37.1" to 37.4" in diameter.

What speeds at what rpm's are you getting now?

This is the online calculator I've used for all my computations:

I have a DT466 in my 1979 Blue Bird full size (66 pax) bus. I drove home from Denver to north of Seattle and made three round trips (1400 miles each) to northern California from NW Washington. Lots of hills on all my trips! On the flats I get just a hair over 9 mpg (usually about 9.2) , in the hills I'll drop into the low 7's. On the trips to California I average about 8.5 mpg.

I run at 55 mph at 2400 rpm. Wide open, foot on the floor, hoping for a tailwind speed is about 57 to 58 mph at 2600 rpm.

If you use 2600 as the rpm, 4.10 for the rear-end, 1.1 for the final gear ratio (allowing 10% slip on the AT545), and 37.1 for the tire diameter that comes out to 63.6 mph. You'd be around 2450 rpm for a 60 mph cruise.

To get to your hoped for numbers it seems you'll have to go a little numerically lower for your rear-end. A ratio of 3.70 would give you 60 mph at 2200 rpm and 70 mph at 2600 rpm (is that your governed rpm?).

What's really hurting you are those itty-bitty tires; do you have room for something taller (like 11R22.5)?
Les Lampman
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Old 01-06-2007, 04:04 PM   #26
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Location: Wyoming & Indiana
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Thanks y'all

Thanks for all the great info. i'm on vacation and will have a chance to reply in a few days.
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Old 01-14-2007, 01:14 PM   #27
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Location: Wyoming & Indiana
Posts: 37
yeah the tires are low profile and a 35" diameter.
You are right, my calculations are a bit off I would be about 63mph at the same rpms i am now running 50-55

60mph @2260rpm doesn't sound too bad for your 295 tires
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Old 02-05-2007, 12:09 PM   #28
Almost There
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Join Date: Feb 2006
Location: Spokane, WA
Posts: 71
Year: 1983
Coachwork: Bluebird
Chassis: International S1800
Engine: SV396 V-8, International
Rated Cap: 66
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Just took a longer trip - my bus (66 passenger, no outrageous body work or lifts, 392 V-8 international running propane, not gasoline) was being used as a moving truck. Fully loaded nose to tail, and towing a Geo Tracker, over the mountain passes from Seattle to Spokane. I found my stock tach was bad - it actually cruises at 55mph at 3200 rpm (the "sweet spot), 60 is about 3500 (what I was driving) and 3600 is redline. Most of the trip was at 60. The passes slowed me to about 25 to 35 mph.

My first trip with the empty bus bringing it home from the school bus yard (200 miles) I averaged 3.25 mpg at about 50 - 55 mph, totally empty and mostly flat. Now, with MSD ignition, fresh tuneup, proper advance timing for propane, and a cold air intake running at 60, fully loaded with a car in tow, I still got 3.25 mpg. VERY frustrating. (The passes were actually 2.85 mpg).

Either - propane is MUCH more inefficient as a motor fuel than gas.... or there are still some things I just haven't found to fix. I may have to drop a 4 bbl carb on there just to try it with gasoline - but at this mileage it means a new bus (can you say Crown? 10 speed?) is in my future for long trips.

Still.... the ride fully loaded was nice - it drove like a dream - and I never even noticed the toad was behind me except when looking for a place to park. Maybe a turbo?

I did notice that ALL the big diesel trucks have much lower front bumpers and air dams for aerodynamic reasons, and all the school buses out there have these "wings" on the back to break up the airflow over the tail. This seems to be a cheap and easy modification - I'll have to try that as well.
Check out the Millenium Phoenix
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Old 02-11-2007, 11:43 AM   #29
Bus Nut
Join Date: Feb 2007
Posts: 263
I own you guys!!!! 18 mpg, 22 ft '86 toyota sunrader. 22RE auto.

I just bought this thing and plan on doing a lap around the country this summer. Reading this board and a few others though have got me jonesin' for a bus....real bad. Problem is, I hate the thought of settling for 10 mpg. I think it can be beat.

What is the most economical engine to run? I am guessing that the 5.9 cummins in a shortbus with a 5 speed and hiway gears ought to do pretty well. This engine will get low twenties pulling a 1 ton dodge pick'em up. I would think that a light shortbus, sorry, no jacuzzi, driven at 55 mph ought to be able to break 15. Which means if I buy that dude's silly wing, I'll get 45, right?

Are there short buses out there with this setup?
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Old 03-12-2007, 09:33 AM   #30
Join Date: Mar 2007
Location: The Texas Borderland
Posts: 43
Year: 90
Coachwork: Blue Bird
Chassis: TC2000
Engine: 5.9 Cummins
Depends on how fast I wanna go. At 68 to 70 I only get about 8.5 but with a little more patience (60 to 62) I'm only at 2200 rpms and get nearly 11. TC2000 35' 5.9 AT545 4.33 and 41" tires. Heck I'm happy with that . . .

BTW if you calculate cubic footage per mile per gallon I beat the heck outa that toyota. It's like Einstein says "It's all relative to your perspective"
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