MPG. Series 60 12.7. Vs M11 Command (370hp)

[coachconverter]

Ive come across some 102D3 buses with the M11/B500R drivetrains.  Im wondering if anyone has information on this drivetrain's fuel performance versus the more common S60 drivetrains out there.

Thanks for any help.

Todd

[Boomer]

Under identical driving conditions the M-11 should get around 1 to 1.5 mpg better than S60, especially at the reduced power rating. Maybe slightly more.  It sounds like these are charter/line haul cars.  There have been problems with the B500's with the retarder due to overheating the trans by untrained drivers.  A lot of drivers fried the transmissions.  I would check to see if upgraded transmission coolers were installed.  This was a problem in that age coach, especially MCI.

[busguy01]

For what its worth. Some years back a friend and I ran nose to tail on a 2000 mile trip - me in a Eagle01 with a 12.7 60 series and a 741 trans - he with a sticks and staples with 370 M11 and 6 speed world. Both about the same weight. Mileage was too close to tell a difference.
JimH

[wg4t50]

Allison Retarder MAX Temp at retarder is 250F, using Transynd have been told by the retired Allison lube engineer that shows up here from time to time.
Problem, its easy to exceed that temp.
I have the. ISM500 with the 4000MHR Trans.  Do love it.

[TomC]

The M11/ISM is one of the best bus engines. While the S60 is bigger (exterior size wise) and is considered to be a million mile engine, the ISM is close at 800k mi. Also the ISM is lighter weight by 650lbs from the S60. The maximum RV power rating on the ISM is 500hp @ 1550lb/ft torque-more then enough. I would use the ISM over the S60 (also a cheaper engine to work on). Good Luck, TomC

[luvrbus]

All you need to know about the M11 engine in a bus can be found at any ABC Bus sales shop there is always 3 or 4 setting on the docks with spun bearings or rods through the block,the casinos here don't get very good service from the M11 in the VanHools only 1 left here and it is used only in emergencies 

The DD's 2 strokes have nothing on one when it comes to leaking oil,if for my personal use I would go with the series 60 or the C12 Cat that was offered in that bus JMO

[Phil H / Chicago]

Hey Todd....I have the M11 450hp /HD4060 6 speed world (which is pretty much same as B500) in my motorhome.....weighs approx 43,000.....got 7 1/2mpg on a trip from chicago to florida with the 10kw gen running some. Kept the speed around 65-70. I know its not a bus so many not help you but figured would let you know.
Phil

[Brian Diehl]

I have a year 2000 Cummins ISM (successor to the M11) that I retrofitted into my 96A3.  It is configured at 400hp and 1450 lbs/ft torque.  I have only put about 50,000 miles on this since I put it in.  I have no oil leaks to speak of except where the wiring harness exits the valve cover.  This engine had an in frame rebuild done before I got it roughly 130,000 miles ago.  Everything runs good and works as it should.  I would not hesitate to go with a M11.  It does sound like you need to watch out for the tranny issues though!  As with any engine - the way it is operated and maintained makes all the difference in the world.  Inspect the bus from the standpoint of maintenance and then decide.  Don't decide on the engine alone.

[coachconverter]

Thank you everyone for the replies.  I'm helping the owner sell three of them, one I got for myself, 138k original miles.  It's rusty but nothing that cant be fixed.  MPG questions usually, for me, boil down to justifying a new vehicle.  I have a perfectly fine 96A3, already painted with 6V92/5 speed ready for conversion.  But I love the look of the D and cant ignore the extra width. 

Thanks again

Todd

[TomC]

I don't think it is an even comparison, comparing non caring, animal bus drivers to a concerned about their own bus conversion owner. I doubt ever will a bus conversion owner drive their bus to the point of spinning a bearing or throwing a rod through the block. Good Luck, TomC

[luvrbus]

It happens TomC I have friends that have the M11 in Eagles Cummins made some great improvements from the M11 to the ISM like heaver rods the Jakes would do a M11 in sometimes and they stopped the oil leak on the left side on the front of the head that was a expensive leak to fix 1000 bucks on the low end

When Brian was looking for his oil pan I told him to check ABC they would have a supply off the M11 and I think he found one there I have never been to ABC there was not 3 or 4 M11 setting on the docks and Todd ask about a M11 not a ISM there is a lot of difference in the 2 engines even if they look the same.

My friend at Cummins now deceased said expect 300,000 mile out of a M11 in a bus he was right on the money from the ones I have been around  

I believe he talked another Eagle owner into keeping his 8V71 instead of changing to the M11 I noticed he is still running his 8v71 and has given up the pursuit of the M11 fwiw 

It would just get a little costly for Todd replacing both the the M11 and B500 with a life expectancy of 300,000 mile on both the M11 and B500

[TomC]

800,000mi is in truck use (what I'm familiar with). 300,000mi in a bus doesn't surprise me. The M11/ISM was a good engine for it's time. I understand why Cummins replaced it with the ISX12. I've driven a few trucks with the ISX12, and I hate to say it-it is a better driver's engine then the Detroit DD engine. Quieter, more responsive, starts quicker-only thing-the Jake is a bit slow to engage. Still-the Detroits are the fuel mileage champs-by .2-.5mpg-which over 120,000mi a year is several thousand dollars savings. Plus the 50,000mi oil change compared to 35,000mi on most other engines. I just found out how much the DD standard water pump (not the new thermostatically controlled) costs new-$60.00. But back to the M11/ISM-I still think it is a great motorhome engine, size wise and servicability wise. Good Luck, TomC

[Jnbroadbent]

800,000mi is in truck use (what I'm familiar with). 300,000mi in a bus doesn't surprise me. The M11/ISM was a good engine for it's time. I understand why Cummins replaced it with the ISX12. I've driven a few trucks with the ISX12, and I hate to say it-it is a better driver's engine then the Detroit DD engine. Quieter, more responsive, starts quicker-only thing-the Jake is a bit slow to engage. Still-the Detroits are the fuel mileage champs-by .2-.5mpg-which over 120,000mi a year is several thousand dollars savings. Plus the 50,000mi oil change compared to 35,000mi on most other engines. I just found out how much the DD standard water pump (not the new thermostatically controlled) costs new-$60.00. But back to the M11/ISM-I still think it is a great motorhome engine, size wise and servicability wise. Good Luck, TomC

Curious, why is there such a huge difference between truck milage and bus milage?

[TomC]

Why is there such a huge difference between truck and bus engine longevity mileage? Bus engines are just in the back doing what they do and most have Allison automatics-meaning they are running at near full power all the time with no rest in between. Trucks, most have manuals (or automated manuals which act like a manual) that don't create the extra heat that Allisons do. Plus the driver's right there behind the engine and can hear or feel something going wrong long before a bus driver could.

I had an owner/operator truck driver come in and tell me he drove 140,000mi a year. With his 1999 Freightiner with Series 60 he changed his oil every quarter when he had the truck inspected. That meant he was doing 35,000mi oil changes! I was about to yell at him for that, but first asked how many miles were on the engine-he said 1.4 million without an overhaul yet. Well, couldn't exactly yell at him with performance like that. Just proves what a really good truck owner can do. Another-when I switched my truck from the 13spd to Allison HT740, I asked the mechanic to keep the clutch. Why? With almost 1.2 million miles on my truck, I had the original clutch in it. I could have installed new pressure plates, givin the flywheel a quick rough up and reinstalled it! This is why the vast majority of big truck companies are switching to automated manual transmissions-whether that be the Eaton Ultra Shift (10, 13, 18spd), Freightliner DT12spd, or Volvo's I-shift 12spd. Takes the driver's shifting out of the equation. Good Luck, TomC