Being GRM, someone knows the answer to this.
What Allison trans would you guys recommend to go behind an M11 Cummins?
yeah I am tired of Mongo being gutless.
BTW I will soon have a 8V71 Detroit and 4 speed manual available, anybody building a Locost?
obligatory rockwell 10 speed troll comment
No manual trans for this swap, towing a trailer behind a 36ft bus through downtown Atlanta is no fun with a manual, I've been there and got the T shirt.
No more manual for Mongo.
Cummins sells many rv spec ism engines. Find a wrecked prevost or similar coach with a cummins motor, take out trans and put it in your bus.
aussiesmg wrote: BTW I will soon have a boat anchor available.
Ftfy
Shouldn't the answer here be a bigger Detroit screamer?
Kenny_McCormic wrote: Shouldn't the answer here be a bigger Detroit screamer?
The Detroit was originally designed as a boat engine, it makes its power way too high up the rpm range to be practical.
The Cummins makes 80% of its torque at idle and maxes at 1200 rpm, before the Detroit even starts making real power.
The Detroit 8V71 is rated at about 600 ft lbs
Nope the Detroit is not the answer
LS1?
Why not go Cat? I thought that was the hot ticket, no?
Btw my offer to pull mongo up the hill at the Mitty still stands. 8)
Fueled by Caffeine wrote: Cummins sells many rv spec ism engines. Find a wrecked prevost or similar coach with a cummins motor, take out trans and put it in your bus.
Here is the answer. Find the newest overdrive bus tranny you can afford. I believe our current MCIs run Cummins with Allison B500/R with retarders, which work like an engine brake to help slow you down. I don't know how much HP they have but taking cops and firemen down south after Katrina they had no problem doing about 80 mph across much of the south
Wally wrote:Fueled by Caffeine wrote: Cummins sells many rv spec ism engines. Find a wrecked prevost or similar coach with a cummins motor, take out trans and put it in your bus.Here is the answer. Find the newest overdrive bus tranny you can afford. I believe our current MCIs run Cummins with Allison B500/R with retarders, which work like an engine brake to help slow you down. I don't know how much HP they have but taking cops and firemen down south after Katrina they had no problem doing about 80 mph across much of the south
Rv and fire rated engines are the most powerful. Buy only by 50 or so horse.
Tom Suddard wrote: Why not go Cat?
Nope. Cat stopped making over thr road engines years ago because their engineers ran out of ideas to make the engines emissions comliant.
M11 has been acquired.
This one has a manual trans so still need an auto.
Would a school bus tranny work? They are all diesel and automatic, but I know nothing about specifics.
A school bus will probably be to small and not geared for highway speeds.
In reply to Fueled by Caffeine:
Ours are commuter buses so I'm sure they aren't the most powerful you can get, they just feel it because they run so much nicer than a transit bus.
have you posted or searched pirate4x4.com? They're a rediculous number of threads on MD/HD drivelines.
In reply to aussiesmg:
You do know that if you change the timing you can actually get boost out of that blower, don't you?
If the engine is in good condition, and you want an automatic anyway, I would consider keeping the detroit and adding an automatic with enough gears to keep it in it's power band. Is that a reverse rotation 8v-71?
You have to be carefull swapping Allison's because the gears are matched to the torque curve and they need max rpm in every gear to shift. So if you are not in the torque curve you run the risk of loping along in an inappropriate gear at every speed. If you go shorter then it would be nice in town but then on the highway you would need an overdrive to have any speed. . And you don't have enough power for an overdrive. If you go taller you will be constantly trying to get the thing to shift up. And when it finally does you will be speeding.
My bus weighs 36000 pounds and is 210 hP. I have already done the math.(and talked to the good guys at Allison)
In reply to bearmtnmartin:
We have done the math, the rear end is a 3.55 on the bus, with a 6 speed (2 overdrives) we should be right in the power band doing our highway runs with the engine just cruising nicely. Should gain a couple of mpg as a bonus.
Also planning on Propane Injection to assist with the hillclimbing.
It appears the Allison MD3060 is the auto I want.
Yes, yes it is. I've been doing some big bus shopping, and the 4speed allison is nicer than the th400 in my old rig, but the 6 speed is more nicerer. An 8.3 cummins with that gearbox in a 38' monster, well, I've driven slower cars. This is what'll power my next rig, whatever it is and whenever that might happen... The only issue I've heard about the 6 speed is that the computerised pushybutton controller kinda likes to take a dump and when it does it's a couple grand to replace, but that the replacement units don't break all that much.
Yep, I heard the same thing about the controllers, but also have a lead on a guy who rebuilds them for about half that amount.
The M11 is substantially bigger and more powerful than the ISC 8.3.
Wally wrote: In reply to Fueled by Caffeine: Ours are commuter buses so I'm sure they aren't the most powerful you can get, they just feel it because they run so much nicer than a transit bus.
The newer motors are so much more powerful than before with a broader torque curve. This has resulted in the need for fewer gears in the transmission. Vgt turbos also have increased throttle response a great deal. Goodness all around.
MD3060 is a good choice, or an MT643...tough trans.
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