Originally Posted by nearhomeless
Narrowing things down in my bus search.
I know there is a best engine thread I started, and also a mileage thread but the mileage thread doesn't say what engine you had so..
I'm hearing people with Cummins 5.9 and Cummins 8.3 report 10mpg or above so far. Is there anyone getting lower mileage with those engines? Is anyone with other engines getting 10mpg or better? Please post, I want to see how common these observations are, and under what conditions. (speed, hills, loads) I kept telling myself "well I dont plan to drive it much at all" but if I plan to put 10,000 miles on it over the next few years, that alone would pay for a $2000-4000 difference in fuel or even a whole 'nother backup bus.
So this is JUST for people getting 10mpg reliably at highway speeds (55mph counts), what is your engine?
The Cummins 8.3 6CTA, ISC, ISL are large engines around 1900+/- pounds plus a transmission to handle that kind of horsepower is needed. THATS some serious weight.
Everything about a schoolbus is marginal except the brakes. Those things got great brakes! ! !
Unlike commercial freight, kiddies dont pay much when being hauled short distances twice a day.
So buses are made JUST beefy enough to get them there and back.
The weakest link are those terrible tiny Allinson 545 automatic transmissions used in buses and RV's and BREAD delivery trucks.
An allison MD 3060 is much better as it is a bit beefier and has a final drive ratio that gives Over Drive capacity and an extra few MPH on the highway. They are found used and rebuilt on Ebay fairly cheaply.
Then you have to have a driveline that will handle those extra ponies.
You're NOT gonna ever spin the wheels on a skoolie. If you try, you're looking to make a $1000.00 mistake or more....
You'll be lucky to get away with only a popped U-joint.
So IF you put the pedal down on an 8.3L Engine, somethings gotta give and it most likely will be the drive shaft or U-joint.
I saw the results of a friend's new employee, that was trusted to drive a large tandem flatbed, after he tried to spin the wheels with a large Caterpillar. The 6 inch diameter drive shaft looked like a pretzel or a piece of play dough a giant had played with.
That was an expensive weekend for Ernie, and Bozo the Clown was looking for a new job.
When the engineers put these things together, engine, CLUTCH, tranny, driveline and rear-end, its all got to be compatible,
horse power-wise. Some leeway is there but you have to play with it carefully..
If you do decide to put an 8.3 in, I would go with a MECHANICALLY injected International DT-466. They can be had off Ebay very cheaply. They have replaceable liners and are infinitely rebuildable and capable of serious horse power if thats what you want/need. And complete rebuild kits are available for the DT-466 inexpensively On-Line.
AND you can avoid the evil and expensive Cummins dealer. I really dislike those guys. I would go with this instead of the stock and much over rated Cummins 5.9L. The weight difference isnt a whole lot for a vehicle meant to haul 71 people.
Some firewall alteration might be needed but thats what bi-metal jigsaw blades are made for.
Get an olde Ford or Chevy VAN engine cover to dress it up a bit and cover that valve cover that will be sticking inside a bit. Take a weekend at most.
You might also want to see about the front end, an extra leaf on the springs to help support the extra 1000lbs that will be residing up there 24/7.
You might want to consider an Eaton manual transmission.
They are cheap when rebuilt and indestructable...literally, in a schoolbus. You couldnt kill one if you tried.
Even a used one that isnt any good for Semi any more will last another 20 years in a skoolie without rebuild.
Put 5 gallons of clean synthetic oil in it and go. The junkyards are full of them.
Something like a RTO9513. Thats thirteen gears. VERY helpful to gradually put beaucoup ponies to the ground without stressing anything unduly. Gently on the throttle. No reason to over-rev and then...skip shift.
Truckers skip shift when empty so as to get quickly up to speed and not over-rev a $30K engine.
A gear for every season or reason.
An RTO9513 ( bread and butter, industry standard) can be purchased (rebuilt) CHEAPLY from almost any truck transmission dealer.
This is a BULLET proof transmission and will last something like a thousand years more or less in a schoolie.
You also dont have to hit everygear. Skip-shifting is very common where every other gear is hit for just a brief bit til you're
up to speed.
The RTO9513 has a final gear ratio 0.68 - 0.75:1 thats Over Drive and give those that desire it an extra 10 +mph on the highway....always nice. AND as an added bonus, with tire chains, you could plow the lower forty with it! ! !
A small amount of air for shifting Hi-Lo range will be necessary; just a little bit, not much.
On my skoolie...which, did I mention, is for sale....
I have a small (Ebay) 12V air horn compressor that also powers my Big Rig air seat and provides compressed air to the Spinner II oil cleaning centrifuge.
With the spinner II, oil changes no longer need take place. http://www.spinnerii.com
This makes using synthetic lubrication affordable as the oil is never thrown away, and makes those expensive engines last SO much longer. UPS etc has been using them for about 20 years now as well as many other penny pinching folks.
The Spinner II can be had (used) cheaply on ebay.
Much can be done mechanically with a skoolie when borrowed properly from their big brothers on the highway.....