8.3 md 3060 mpgquestion

Bus dad · 09-06-2013, 12:04 AM

Wondering if anyone has the 8.3 with the md 3060(5speed overdrive) 5.38 rear end. what kind of mpg (78 pass) I have think it would do better than 5.9 with 4.78 (643) Anyone w info on this would be appreciated.
Thanks
David

crazycal · 09-06-2013, 01:15 AM

Somewhere between 24 and 26 mpg...lol. This is only downhill.

gusbus · 09-06-2013, 06:03 PM

bansil · 09-07-2013, 05:50 PM

On flat ground and hills the big loaf of bread will get 'bout 10 with a deisel....period plus/minus 1 or 2
.
.
People always say "how can you afford to enjoy the bus, with the mpg it gets?"
.
.
My answer is this "can you tow your house,apartment or hotel around and get 10 mpg?"
.
."never thought of it like that"

crazycal · 09-08-2013, 01:25 PM

Quote:

Originally Posted by bansil

On flat ground and hills the big loaf of bread will get 'bout 10 with a deisel....period plus/minus 1 or 2
.
.
People always say "how can you afford to enjoy the bus, with the mpg it gets?"
.
.
My answer is this "can you tow your house,apartment or hotel around and get 10 mpg?"
.
."never thought of it like that"

I think it'll do better than that. My 89 BBAA with an 8.3 and a MT643 got 10.5 from AZ back to CA. it had a 4.10 rear end. That included the grape vine and hills. The 3060 is a double overdrive. I bet if the revs are kept at 1800 or less, the mpg will be 12.

family wagon · 09-08-2013, 07:38 PM

I'm almost there... 2000 Blue Bird with an ISC 8.3 (24 valve) engine and B400 trans, which I think has the same ratios as the MD3060, and a 5.38 axle. Unfortunately the programming on my transmission doesn't allow use of the second overdrive.

We averaged 9.25 MPG over a 1700 mile trip through Utah, Wyoming, Montana, and Idaho last month. Oh, the bus is a flat-nose 36k gross weighing around 23k currently.

crazycal · 09-08-2013, 09:57 PM

Sorry, my bad. Double overdrive is only with 6th gear enabled which none of the school buses have.

wmkbailey · 09-09-2013, 10:26 AM

Quote:

Originally Posted by crazycal

Sorry, my bad. Double overdrive is only with 6th gear enabled which none of the school buses have.

I have the MD306 on my bus and they will not program the sixth gear unless they get permission from Allison. I wonder if, when I'm done and re-weight the bus, showing the lower wiehgt. Would they would allow it to run with the sixth gear overdrive? hmmmm.

Jarlaxle · 09-15-2013, 08:21 PM

Quote:

Originally Posted by crazycal

Quote:

Originally Posted by bansil

On flat ground and hills the big loaf of bread will get 'bout 10 with a deisel....period plus/minus 1 or 2
.
.
People always say "how can you afford to enjoy the bus, with the mpg it gets?"
.
.
My answer is this "can you tow your house,apartment or hotel around and get 10 mpg?"
.
."never thought of it like that"

I think it'll do better than that. My 89 BBAA with an 8.3 and a MT643 got 10.5 from AZ back to CA. it had a 4.10 rear end. That included the grape vine and hills. The 3060 is a double overdrive. I bet if the revs are kept at 1800 or less, the mpg will be 12.

Gearing is similar: OP's bus has 5.38 gears, the final drive is about 3.90 in (0.71) OD. 1800RPM should be about 60MPH.

family wagon · 09-15-2013, 08:31 PM

Quote:

Originally Posted by wmkbailey

Quote:

Originally Posted by crazycal

Sorry, my bad. Double overdrive is only with 6th gear enabled which none of the school buses have.

I have the MD306 on my bus and they will not program the sixth gear unless they get permission from Allison. I wonder if, when I'm done and re-weight the bus, showing the lower wiehgt. Would they would allow it to run with the sixth gear overdrive? hmmmm.

My local Allison dealer won't re-program mine without approval from the OEM -- a letter from Blue Bird's powertrain engineering group, in other words. I talked with a guy in (one of?) their offices in Georgia this summer and learned that they never designed an ISC 8.3 - B300R 6 speed power train, so he couldn't approve it. If you really do have MD3060 instead of B300 it might be a different story.. but I doubt it.

Bus dad · 09-18-2013, 03:59 PM

Thank for the response. I was struggling between the 5.9 with 643 and 8.3 with 3060. We ended up getting the 8.3 with 3060. IN the mountains coming from Oregon and Idaho we avg 10 going 60. when we went up to 70 it went down to 8.8. But when I went 55-57 we got 12.45 ( Nebraska). Thanks for all of your responses. Just out of curiosity does anyone know how the 5.9 did with the pushers with the world tranny.

anyway thanks again

David

syke · 09-18-2013, 05:45 PM

I find it sad that a mechanics shop would not re program the trans for you. It's a private vehicle at this point so no chance of a school district coming down on them. I'd ask to sign whatever "release of liability" paperwork the mechanic could come up with and unleash that bad boy!

Wishful thinking... i know.

My poor 643 just can't muster a 5th or 6th gear no matter how hard I try. I'm jealous

jhagan · 12-04-2016, 01:37 PM

We have all ours unlocked. Go to your local OEM dealer of your bus, speak with the Service Manager and tell them you need to submit a work order to the OEM for permission to unlock your 6th. The OEM will send you a letter, you then send it to your Allison's dealer. Allison will send you a liability release waiver, then will release the programming to the service techs. Ask them to activate your Economy Mode if it isn't already. This lowers your shift point, thus resulting in slightly better fuel economy. All our 6th gears are unlocked and kick in around 49 MPH (depending on your rear ratios) and reduce our RPMs by 300-350. When you do that on a "pusher", I encourage you to clean and flush your radiator and possibly install new thermostats that run about 20 degrees cooler. Remember, when you reduce your RPM, you also reduce your cooling capacity for the engine.

jasong71 · 12-10-2016, 04:16 PM

Quote:

Originally Posted by jhagan

We have all ours unlocked. Go to your local OEM dealer of your bus, speak with the Service Manager and tell them you need to submit a work order to the OEM for permission to unlock your 6th. The OEM will send you a letter, you then send it to your Allison's dealer. Allison will send you a liability release waiver, then will release the programming to the service techs. Ask them to activate your Economy Mode if it isn't already. This lowers your shift point, thus resulting in slightly better fuel economy. All our 6th gears are unlocked and kick in around 49 MPH (depending on your rear ratios) and reduce our RPMs by 300-350. When you do that on a "pusher", I encourage you to clean and flush your radiator and possibly install new thermostats that run about 20 degrees cooler. Remember, when you reduce your RPM, you also reduce your cooling capacity for the engine.

Wow, great info. Thanks!

2kool4skool · 12-10-2016, 05:09 PM

Lousy mpg for a vehicle, great mpg for a house.

PNW_Steve · 12-10-2016, 06:41 PM

Quote:

Originally Posted by jhagan

We have all ours unlocked. Go to your local OEM dealer of your bus, speak with the Service Manager and tell them you need to submit a work order to the OEM for permission to unlock your 6th. The OEM will send you a letter, you then send it to your Allison's dealer. Allison will send you a liability release waiver, then will release the programming to the service techs. Ask them to activate your Economy Mode if it isn't already. This lowers your shift point, thus resulting in slightly better fuel economy. All our 6th gears are unlocked and kick in around 49 MPH (depending on your rear ratios) and reduce our RPMs by 300-350. When you do that on a "pusher", I encourage you to clean and flush your radiator and possibly install new thermostats that run about 20 degrees cooler. Remember, when you reduce your RPM, you also reduce your cooling capacity for the engine.

Hey Jhagan,

Thanks for the info. I have been pursuing getting the 6th unlocked on my Bluebird w/8.3 & MD3060.

Can you tell us what manufacture buses you are running? I have heard that some with Thomas buses have had success getting a letter but Bluebird won't play ball.

Does this jibe with what you experienced?

Thanks.

S.

Thomas1985 · 12-10-2016, 11:40 PM

I'm looking at a 1998 bluebird handy bus 8.3 cummins diesel that's in Colorado. He says it has a five speed Allison transmission. It's a rear engine. Those of you experienced with this engine. Are there any known issues I should be aware of? Do you feel that it's very reliable? It currently has 260,000 miles. Any opinions? I'm out of state so I only started speaking with him. I was thinking though that given the location it probably already geared for highway and mountain climbing which will be my intended use. I need something to travel across the country and we often visit the smoky mountains.

-Thomas

Bklucky19 · 03-26-2017, 11:08 PM

Quote:

Originally Posted by jhagan

We have all ours unlocked. Go to your local OEM dealer of your bus, speak with the Service Manager and tell them you need to submit a work order to the OEM for permission to unlock your 6th. The OEM will send you a letter, you then send it to your Allison's dealer. Allison will send you a liability release waiver, then will release the programming to the service techs. Ask them to activate your Economy Mode if it isn't already. This lowers your shift point, thus resulting in slightly better fuel economy. All our 6th gears are unlocked and kick in around 49 MPH (depending on your rear ratios) and reduce our RPMs by 300-350. When you do that on a "pusher", I encourage you to clean and flush your radiator and possibly install new thermostats that run about 20 degrees cooler. Remember, when you reduce your RPM, you also reduce your cooling capacity for the engine.

Any chance you could tell me which dealer you went to? I have all OEM paperwork but continue to be told Allison corporate won't respond. Thanks

Brewerbob · 04-04-2017, 02:48 PM

Miles per gallon of diesel fuel or miles per gallon of tranny fluid? Ask Lolmstea; she knows the answer to both of those.

joeblack5 · 04-04-2017, 03:54 PM

I am amazed that these busses get that good of a mileage. Our 7.3 powerstroke mini bus E350 gets 13Mpg. That is doing 55 -60 mph. Hard to imagine that something 5 times as heavy, wider and bigger tires can still do that good. I would have thought between 6 and 8 mpg.

later J

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