My new Series 50, 4.11 geared "RTS" got 10.75 mpg in short test yesterday

Kevin Warnock · May 07, 2007, 07:10:08 PM

Hello,

I did a short test of the fuel economy of my new Series 50 powered, 4.11 rear end gear ratio TMC "RTS" bus yesterday. I filled it at a truck stop, drove it 102.4 miles at 60 miles per hour, checking the speed every 15 seconds or so (that's work), and then filled it again at the same pump, with the bus oriented the same way. I used 9.524 gallons, for 10.75 miles per gallon. The bus is stripped, and only had the house batteries, some sheets of plywood and some empty water tanks on board.

The top speed is 75 miles per hour. I was able to go 62 miles per hour up a 1,000 foot grade that my old bus, a non-turbo 8V-71 powered MCI 5a, 35' x 96", could only take at 50 mph. My new RTS is 40' x 102" and has a turbo Series 50 engine that the computer says has only 6,000 miles on it. (Did I get a rebuilt engine, nobody knows...)

I am pretty pleased with the results of my test. I know I need to do a longer test for better accuracy, but this test should be pretty close for steady freeway driving at a moderate speed. The engine hardly seems to be working at 60 mph. The air conditioning worked fine - my first real test since I bought the bus in March. I could tell in 1 minute if I turned it off, as there is essentially no insulation in the bus right now, as I stripped the walls and ceiling of the factory insulation. Oh, I did turn the AC off during the fuel economy test, for the record, as I was trying to see the maximum economy I could get.

How much do you think the fuel economy will go down once I complete the conversion, if at all?

Thanks,

Kevin
San Francisco, CA

NJT 5573 · May 07, 2007, 08:03:24 PM

Your not going to make any friends getting 10 MPG. My DDEC 6V92 got 6 one time when the pump belt for the fan was loose. I hate you!

Hartley · May 07, 2007, 08:29:03 PM

Quote from: NJT 5573 on May 07, 2007, 08:03:24 PM
Your not going to make any friends getting 10 MPG. My DDEC 6V92 got 6 one time when the pump belt for the fan was loose. I hate you!

Haa.. My 83 NJT (6575) got 7.7 running on veggie/mix and 5.5 on low sulphur diesel on return trip from Charlotte in January.
Pulling a 24 foot trailer. I get about 6 mpg normally. ( MUI engine )..

RJ · May 07, 2007, 08:39:51 PM

Kevin -

Keep your bus on a diet as you complete the interior.

Weight is a major culprit, both curb weight and that of right shoe.

Cruise control will help, Rostra or King. May even have one programmed into the DDEC on the S-50, just needs to be unlocked.

Any size tire (22.5 or 24.5) turning LESS than 495 revs per mile will help.

60 - 65 mph comfy cruise, when fully outfitted, should return overall average of 8 - 9.

All buses have the aerodynamics of a brick at speed - keep the silhouette as clean as possible for best results.

What transit property ran your RTS in revenue service? Golden Gate?

What's the VIN on your coach?

FWIW & HTH. . .

Gary '79 5C · May 08, 2007, 02:23:42 AM

Congrats, both on your mileage, and your Patience to drive 60.
The 6V92 turbo non DDEC, I run at 70 mpg gets about 6.7 mpg.
No bus air/conditioning running. I wonder as to how I would do at 60 MPG. Just never had the time it seems.
Maybe in retirement I will feel I have the time, but that is dependant on the housing slump another thread.
GP

PS TG for the spell check.

NJT 5573 · May 08, 2007, 09:09:52 PM

MUI is beating DDEC by 1.5 MPG or more. Stupid computers!

wvanative · May 12, 2007, 04:11:08 AM

Quote from: Gary '79 5-C on May 08, 2007, 02:23:42 AM
Congrats, both on your mileage, and your Patience to drive 60.
The 6V92 turbo non DDEC, I run at 70 mpg gets about 6.7 mpg.
No bus air/conditioning running. I wonder as to how I would do at 60 MPG. Just never had the time it seems.
Maybe in retirement I will feel I have the time, but that is dependant on the housing slump another thread.
GP

PS TG for the spell check.

Gary,

As Curly use to say to Mo "I resemble that remark"I can remember when I was in my 20's I would drive home from Chicago to Wva in less than 7hrs now it's just over 8hrs. but that was back in the 70's when I think the speed limits were 70mph, and I know I was way over that speed lol. Now I find myself right on 60mph all the time in my car, man I hope it's not old age thats causing me to drive slower. I hope it just the arthritic foot I have LOL. At least that the story I'm going with.

WVaNative

Dreamscape · May 12, 2007, 04:24:25 AM

I typically get around 8 mpg, give or take, 8V71 with standard crash box. Getting anything over that is only a dream. It all depends how heavy your foot is and how many hills you have to go up and what color your exhaust smoke is.
What it is, is what it is.
It will change as you add more weight, so feel good now.

Happy Trails,

Paul

Dreamscape

csrddcd · February 23, 2018, 05:27:39 AM

Kevin, what transmission do you have in your RTS?

Do you have OD?

What are the trans and OD ratios?

I have a repowered MC9 with a series 50 and 3.73 gears and want to find some 4.11 gears to swap mine out. Currently have too much top end and could use a bit more get up and go from a dead stop. Power on hills is good now.

Thanks

Geoff · February 23, 2018, 06:19:02 AM

With a fully converted RTS (32,000-34,000 lbs.), 350HP 6V92TA, 4:11 gears, running the diesel genset, I get 8mpg @ 62-65 mph.

luvrbus · February 23, 2018, 06:23:25 AM

That is a 11 year old post wonder how it is doing now on fuel with all the climate changes

chessie4905 · February 23, 2018, 06:44:52 AM

Empty shells have lots of power and get great fuel mileage. Even our 4104 felt fast before conversion. Btw it had hv9 injectors and two valve head then, smoked like a locomotive but sure ran good. He will end up with 8 to 8 1/2 average, unless it is a minimal conversion.

luvrbus · February 23, 2018, 06:47:52 AM

Quote from: chessie4905 on February 23, 2018, 06:44:52 AM
Empty shells have lots of power and get great fuel mileage. Even our 4104 felt fast before conversion. Btw it had hv9 injectors and two valve head then, smoked like a locomotive but sure ran good. He will end up with 8 to 8 1/2 average, unless it is a minimal conversion.

Depends on the direction the wind is blowing too

figure on 5 to 6 mpg and enjoy the savings at Mac Donald's or Burger King

HB of CJ · February 23, 2018, 10:07:33 AM

My old Crown Supercoach 40 foot 3 axle 10 wheeler ex school bus got around 10.5 mpg from Apple Valley CA to Cave Junction OR. VIN 37317.

About 60 mph tacking about 1500 rpm in tenth gear. 12Rx22.5 tires. 3.90 gears. .82 to one overdrive. Fuller RTO910. Small Cam 250 Cummings (sp?)

No turbo. Climbed the 6% and 7% grades at around 45 mph in 8th gear tacking about 1800 rpm. Slow. Curb weight then stripped was about 24500 pounds.

Long ago. CROWNS FOREVER!

Geoff · February 23, 2018, 11:21:24 AM

The RTS was designed and tested in a wind tunnel for wind drag. It also stands at about 10 feet high with 20" bays. So great fuel mileage is not just being empty.