I am more of a reader than a poster as most stuff has been covered. I am not an expert in any this by any means, but I am a good reader and follow directions. I need to thank all of you smart guys for the great information you have put in this forum.

I am having an issue deciding on a direction for the next power plant. I AN NOT trying to start a debate on which of these engines is better, there are plenty of those threads out there. I am more interested in my particular situation where to go.

I have a 1993 30' (~15,000lbs) bus built on the GMC P3500 forward control chassis. The 6.2L in there is tired, but runs well, and not the right fit (no surprise there) though it is the military spec version. Flats we sometimes get 65MPH, hills are a joke. What i do like about the motor is how simple and cheap it is to maintain as well as parts being easy to get. However I need to be able to cruise at 70MPH and climb hills reasonably. We drive this bus cross county about once a year and around the region about once a month.

I have been leaning towards a 94-98 6BT as a replacement, they seem simple to setup and maintain and there are parts everywhere. I have read though all of the items needed for the conversion and I am up for the challenge. However, an LMM with 175K has become available complete with the Allison 1000 and the harness and computer out of a wreck for a very good price, similar to what ill spend on a 6BT and a good 47rh.

Either option is going to be similar in $$ and swear words, so that is not a factor.

Question here is which direction would you go? the LMM scares me due to the price of parts (Injectors!) as well as how much more complicated it is than a 12V, though I do like the promise of 650 lbs torque and an Allison 1000.

 

I all honesty I would lean towards a Cummins 8.3L for what you are trying to accomplish, the Allison 1000 is a light duty transmission so is the 47rh, neither a meant to push a buss, If you can find a old freightliner set up with a 8.3L cummins and a 2000 series allison I think you will be much happier with that set up that with a 5.9L or allison espically if you want to climb hills, just food for thought.

 

Well, I say bus, but it is a short bus, not a full 40'. My thought is with the meager 6.2 bolted to a 4L80E we are getting by, just slowly. The 6BT gets us over another 100lbs of torque stock.

My other thought is there are 3500HD Silverado rigs that weigh ~6000 lbs plus a 10,000 lb towing capacity. Looking at the Allison 1000 from what I can find they rate up to 19,000lbs. I see these rigs and other Pickups (24V/PS7.3) pulling heavy trailers at 75 without issue.

One part of the puzzle is room. With the FC chassis, there is only so much room to clear the floor and doghouse cover. A 6.5 with the Turbo setup would consume most of it, a 5.9 is going to have some height issues as well but I can over come them.

The other part of this puzzle is I need to have easy access to parts while traveling so I am sticking to pick-up truck drivetrains. Moving to an 8.3 puts me into heavy truck shops and parts suppliers only.

 

I got ya, for a short bus a 5.9L will suffice then, sorry for that misunderstanding,