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Old 05-24-2009, 03:07 AM   #1
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Join Date: May 2009
Location: Minneapolis, Minnesota
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Year: 2012
Coachwork: Need bus-as-home over RV
Chassis: still looking
What is the best engine to look for?

Whether in terms of ample power, economy differences (if any observed), reliability, and repair costs? What older engines may be more expensive (than modern ones) to fix due to harder to find parts?

Since this seems to be a major component and kind of the heart of the bus I figure I better give it extra attention and research.


For instance as far as gasoline goes, I like the GM 427 simply because it's built roughly the same as the car/light truck engines so i'm familiar with it, can adapt car/truck parts that I assume are cheaper to it if needed, and probably replace the whole thing with a normal car/truck engine if it blows up in some pinch. It should have adequate power, and be cheaper to fix, parts availability every junkyard in america, just lower economy than a diesel. I'm not even sure if there are many other gas engines out there besides the 366 for that matter and the guy with a 350 small block. (did anyone put the Ford 460 in a full length bus chassis or the Triton V10?)

As far as diesels go there's a wider range depending on year, but i'm wondering if there are any downsides to the International DT466. Impressions I get are reliable, powerful, and being modern should be easy to get parts... are there any knowingly better diesels out right now whether newer or older? (better can include "more suitable for WVO conversion" for instance) If you could have any of the diesels currently in use or on the market in available schoolbusses (no Volvo D16's :P ) what would you take and why? If you couldn't get a DT466 what would your 2nd and 3rd choices be/what else is real good?

I've heard people say Detroit Diesel 8.2L's are unreliable, and Cat 3208's are more expensive to fix than the DT466. There's always the Cummins 5.9 like used in the light trucks, how does that compare to the DT466? I've heard in rumors to avoid the Ford 7.3 in busses. What say you?
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Old 05-24-2009, 09:18 AM   #2
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Re: What is the best engine to look for?

here is my opinion on bus engines.....

a diesel will pay for itself in a single trip cross county in the fuel savings over a gasser. There are exceptions, like i think steve's bus gets around 10 mpg, but the gas buses i've been around are full size and get about 5 mpg or less.

it seems the dt466 is widely considered one of the best skoolie engines because of it's longevity and durability. parts are also readily available. the cylinder liners can be changed while the engine is in the chassis which makes rebuild cheaper and easier...but who ever rebuilds a bus engine? They seem to run forever, and if the engine or trans died, you could buy a "new" bus cheaper than rebuilding an engine. Less fuel efficient than the dt360 so i've been told.

The smaller cousin dt360 is nearly identical to the 466, just less hp, less displacement, and slightly better fuel mileage from what i've been told. I drove about 30K miles in a skoolie with dt360 and was very pleased with performance and durability, but not so much with fuel economy. Once I did drive with the bus loaded with about 20K pounds of stuff which was way over the buses gvw. i figure she ran at full throttle for about 110 hours from mi to nv and back and she never missed a beat. She had about 200K on the odometer. even when empty, i think i averaged about 7 mpg or so.

The cummins 5.9 is my favorite skoolie engine. It gets way better fuel economy than the dt360 (both are exactly the same displacemennt 5.9 liters = 360 cubic inches) and is available with more hp than the dt360. parts are available everywhere...but again, who's working on bus engines? In the 6 years and prob 60K miles i've driven my various buses, i think the only engine component i've replaced was a water pump...and it was still working, it was just leaky. Alternators don't count, i've consumed many alternators, bought new tires, windows etc. I've always had really good luck with bus engines. When phill and i took our buses ona trip to texas together, he got about 50% better fuel economy with his cummins 5.9 than i got with my dt360

Ford Brazilian/new holland 6.6 and 7.8 liter motors. I used the 6.6 for a bunch of miles. it was a turd as far as power, but was very reliable. it was the best cold starting diesel i've had. Even when it was zero outside she would still start. The dt 360 was also 2nd best in the cold, followed by the cummins which really doesn't like cold at all, and the detroit diesel 2 stroke 6v71 would refuse to start without help when it was below freezing. I had, about 300K miles on this 6.6 liter engine, including about 10K miles on veggie. oh yeah....i did put a starter on this engine, almost forgot about that. I think the starter got worn out because of the wvo....i did my own system and had fuel delivery problems on occasion that required the starter to work for long periods of time. Parts are less available for these engines so i've heard...but then again, who works on bus engines? did i mention that yet?

the big cummins 8.3 is supposed to be a great motor, i have no expierence

i would tend to stay away from any v8 diesel. the ford/navistar 7.3 is a crappy motor in a ford van chassis, so i can only immagine how terrible it is in a full size bus. the 9.0 liter international is rumored to be a boat anchor....but a very fuel efficient boat anchor, the detroit diesel v8..is it an 8.2 liter? or somehing, i hear those are not the best skoolie engines, the 6.9 ford would be miserable, that motor in a van doesn't make enough power to get out of it's own way, the chevy diesels can't possibly make enough power for a bus, and they aren't build heavy duty like an inline 6 cylinder. Not to say that you couldn't have good luck with one of the above motors in a bus, and if the right bus came along for the right price perhaps a v8 diesel wouldn't be a deal killer.

my favorite engine so far has been the cummins 5.9. Fuel is the biggest expense when it comes to a skoolie, at least for me. Way more than the cost of the bus, or the cost of conversion. Therefore i think that fuel economy is one of the most important factors.

at diesel prices of $2.30/gallon lets look at what it would cost to drive 10K miles.

10 mpg (cummins 5.9) $2,300

7 mpg (dt360) $3,285

4.5 mpg (gasser) $5,111


So in 10K miles, you will have saved enough money in fuel with a cummins vs a gasser to pay for a brand new bus. and chances are that you can drive 50 or 100K miles before you actually need to think about getting a new bus.
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Old 05-24-2009, 12:30 PM   #3
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Re: What is the best engine to look for?

all of the inline 6 diesels are good, i'd go with the larger engines as a first choice because they don't have to work as hard as a smaller engine to move you down the road. once your moving an engine only makes the amount of power that you need to maintain road or governed speed, the larger engines have more power to get you up to speed faster and then fuel back to maintain speed sooner resulting in better mileage, they also have more power for hill climbing/maintaining road speed.

my first choice is not available as a truck engine, second choice is a toss up between the cummins 8.3 and navistar dt466 with the cummins as a preference just because it's a cleaner looking package but not necessarly any better.

the cummins 5.9 and dt360 are also a heads up match for power and reliability, 5,9 parts are more available because everyone uses them, dodge pickups as well as all of the medium truck builders and construction equipment mfgs. dt360's parts are available at any ih tractor or navistar truck dealer. the dt360 is "in chassis" rebuildable because it is a sleeved engine while the 5.9 is not.
as lapeer pointed out who rebuilds their bus engine?

as far as gas engines go the gm 427 and 366 truck engines are tall block engines and different from the passenger big blocks, before the mid/late 80's gas engines were the standard in medium duty trucks, part of that standard was that at somewhere between 75 and 100 thousand miles you would need to replace the engine and often as not they would just run until they came apart with no warning. it doesn't matter who/what gas engine you have plan for a new gas engine somewhere around 75k miles even with a modern engine.
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Old 05-24-2009, 12:33 PM   #4
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Re: What is the best engine to look for?

Quote:
As far as diesels go there's a wider range depending on year, but i'm wondering if there are any downsides to the International DT466
The asking price. Best medium-duty engine ever built, bar none. It was a 60's tractor engine, and still is being made today (as the MAXX-Force DT). Lapeer is right about the DT360, and what he said there also apples for the most part to the DT408. The DT466 was replaced by the DT466E around 1995.

The 466 is an excellent cold starter...I've seen one pop without ether, a block heater, or even an intake heat grid (the 466 didn't get one until about 2004, and that was for emissions, not cold-start problems) over 650,000 miles in sub-zero weather. Any 2-stroke Detroit needs to be ethered in very cold weather (though I've lit off 6V and 8V71's without help in 25-degree weather). This is by design...you're SUPPOSED to ether it. The smoke cloud until they warm up is a little alarming at first but normal.

I like the 5.9 Cummins a lot, though bus versions tend to be WAY down on power (I've seen 160HP in a 40' bus). The older 12V 6BT mechanical engines are less money (and use a bit less fuel) than the late-1998 and newer 24-valve ISB's. Any dealer can turn up a 24V with a computer.

The 8.3 (Cummins C) is the 5.9's big brother...another excellent engine, though rare in buses.

International's 6.9 and 7.3 IDI engines aren't bad, but are absolutely unforgiving of abuse or neglect. The 7.3 IDI turbo in my F-350 wound up over 366,000 miles before I sold it...it's still going and close to 400,000 miles. I'd have no problem owning one in a bus, but would have to have PLENTY of service records. They're not especially powerful, especially in the mountains (usually no turbo).

The T444E (IH's version of the 7.3 PowerStroke) came out around 1995 to replace the 7.3 IDI and is more durable and usually more powerful (usually 170 or 190HP in a bus, but any dealer can turn it up to 210)...not as forgiving as the 466, but not bad at all. I drove one (190HP) with 325,000+ miles and over 25,000 hours in a 1997 IH 3800 shuttle bus. They run hot...you'll se 210+ degrees on the gauge, especially climbing hills. This is normal and won't hurt anything.

The 9.0 International and 8.2 Detroit are lousy. I wouldn't own one if you gave it to me. The "Triple Nickel" (555ci) Cummins is even worse.

The biggest downside to the 6.6 Ford/New Holland, the DT360, 5.9 Cummins, 6.9/7.3/T444E International, and even the 8.2 Detroit is often what's BEHIND it. Most of these will have the Allison AT545 bread truck transmission. These don't lock up, which makes them pretrty dismal on the highway & in the hills. I have never seen a 466 with an AT545--automatics are usually the far-superior Allison MT643, which DOES lock up in high gear.

Quote:
it doesn't matter who/what gas engine you have plan for a new gas engine somewhere around 75k miles even with a modern engine.
Absolute tripe. Unadulterated BS from beginning to end.
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Old 05-24-2009, 11:41 PM   #5
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Re: What is the best engine to look for?

Quote:
Originally Posted by Jarlaxle

Absolute tripe. Unadulterated BS from beginning to end.
everyone is entitled to an opinion,

but after working as a truck mechanic for several large rental fleets and then spending 10 years in the engine test field for a major tier i engine parts supplier, my experience was that after the ford f600's hit 80k miles it was a crapshoot if they would make it to 100k without a replacement, probably 20 percent of the fleet had replacement engines by the time that the trucks were mileaged out at 100 k. I changed enuff of them that I had it down to a 5 hour job.
my experience with gm tall blocks in tandem axle dump trucks and c 70 tractors was that 2 mechanics could change one on the side of the road in a day and that includes driving 100 miles one way, again some where around 75k miles seemed like the magic number.

durability testing on the new engines show that 100k miles is the designed life span in a severe enviroment, if you use the engine at normal automobile/pickup duty cycles and perform the recomended maintainence at regular intervals, they will live for 250k miles.

i worked on one engine that was in for extended durability testing that lived past the equivalent testing of 1 million miles, 249 others failed at less than 500k miles, all were identical pre production test enines that are available today at your local light/medium truck dealer.

to jump into a gas bus with more than 75k miles on it and think that it has another 25 to 50k miles on it without the posability of needing major work is foolhardy based on my experience, it is also a large part of the reason that most medium duty trucks are using diesels, along with the fuel savings and extended life expectancy of the trucks.
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Old 05-25-2009, 12:29 AM   #6
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Chassis: International Cornbinder
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Re: What is the best engine to look for?

Any inline 6 cummins or international would be ideal IMO. My dt466 has plenty of power on tap.
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Old 05-25-2009, 10:13 PM   #7
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Re: What is the best engine to look for?

The original 370 in my bus went 160,000 badly-neglected miles. There's an F-700 wrecker where my wife works with over 120K on a gas 429 that runs like a top. The old F-800 rollback wound up close to 70,000 miles (plus Fates only know how many it already had) on its little 361FT. I've seen and driven an International Load Star with close to 300,000 miles on an unrebuilt gas 345 engine. Also seen and driven an old Chevy C-50 that wound up close to 200K on its underpowered 366 (it's wound up about 50K on the crate 502 that replaced it since then). Neglect them (like most fleets seem to) and you'll blow it up, sure. Maintain it, and it will run a long time.

I saw a Ford V-10 wind up over 400,000 miles in something that's driven pretty hard: an F-550 4x4 repo truck.
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