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Old 11-15-2019, 12:31 PM   #1
Skoolie
 
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I Want a Hot Rod Bus!

Right now Iíve got 300 horse power and a six-speed that has my engine turning 2200 rpmís at 80 miles an hour. What I need is more power for passing and climbing mountain passes. I think 400 - 500 hp is what I need. Iím thinking of putting the bus on 24.5 inch wheels with taller tires to effectively give me a taller final drive ratio. My reason for the big power number is headroom. I hate running with a vehicle floored and maxed out. I basically just want to be able to run 75 miles an hour with the engine in a more relaxed state. And I want safer passing. I also hope that with the right build build I will be able to bump my fuel mileage up. Iím going to look into a Cummins 8.3 swap in favor of the C7 that I have now. Ideally it would be a common rail engine that I control with the electronics from a 5.9 Dodge/Cummins and find a way to run a built Allison 1000 with a stand alone controller. It is important to my goal to get away from the proprietary computer programming that Thomas/Cummins/Allison have on these buses and instead use the Dodge Cummins/Duramax Allison software that is so widely available and less costly. I think the hardware, software and the knowledge base are out there. They are just unfamiliar to us folks in the skoolie community.
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Old 11-15-2019, 01:03 PM   #2
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There are people racing tractor trailers --
They probably have a forum or two...

With bigger wheels and tires (rolling mass) consider upgrading brakes.
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Old 11-15-2019, 01:16 PM   #3
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There are people racing tractor trailers --
They probably have a forum or two...

With bigger wheels and tires (rolling mass) consider upgrading brakes.
Good point. On every build that I’ve ever done, upgrading the brakes has always been a consideration. Even on my Toyota 4 x 4 pick up, I am running Land Cruiser and Tundra brake parts and the results are just amazing. Some of the best braking I’ve ever experienced.
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Old 11-15-2019, 01:35 PM   #4
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There are people racing tractor trailers --
They probably have a forum or two...

With bigger wheels and tires (rolling mass) consider upgrading brakes.
They cap the mph at 100 on race trucks.

Bus tires aren't rated much higher than 80 so bear that in mind.
Why not just sell it for top dollar on FB and get a bus with the drivetrain you're talking about. WOuld be a hell of a lot easier than a swap.
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Old 11-15-2019, 01:49 PM   #5
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Quote:
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There are people racing tractor trailers --
They probably have a forum or two...

With bigger wheels and tires (rolling mass) consider upgrading brakes.
Trucks, yes, trailers, no.
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Old 11-15-2019, 03:24 PM   #6
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Originally Posted by EastCoastCB View Post
They cap the mph at 100 on race trucks.

Bus tires aren't rated much higher than 80 so bear that in mind.
Why not just sell it for top dollar on FB and get a bus with the drivetrain you're talking about. WOuld be a hell of a lot easier than a swap.
Your point is well taken, but I looked for a long time before I found a clean HDX with extended headroom, air ride, underbody storage, professionally painted, passenger compartment air conditioning and zero rust. I was wondering if Thomas was even dealing with Cummins in the mid-2000s. I think itís gonna be hard to find anything comparable. Maybe somebody wants to pitch me on the merits of some other make and model?

As for the speed ratings of bus tires, I mention that I was thinking about changing my wheel size. It would get me two things, lower RPMs for my whole drivetrain including my wheels and tires and a little more ground clearance, which I sorely need if I hope to drive on anything but the smoothest pavement. My bus is so low slung right now that the skid plate under the engine and the one under the front steps touch down with surprising regularity. I have always understood that the guys who run heavy loads very fast out west prefer 24.5 wheels and tires because they are more suited to the speeds
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Old 11-15-2019, 03:31 PM   #7
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I have been considering getting out of buses entirely and doing something with a class 8 road tractor. I wonder how it would be to get insurance for something like that.
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Old 11-15-2019, 03:35 PM   #8
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I have been considering getting out of buses entirely and doing something with a class 8 road tractor. I wonder how it would be to get insurance for something like that.
Bout the same as a bus. I heartily support folks doing this! I want a toterhome some day. I'd love a Pete.
If you aren't familiar google toterhomes and skip over the brand new super expensive stuff.
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Old 11-15-2019, 05:18 PM   #9
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You already have a hot rod bus. For the performance you want you will have to go to a class 8 coach or truck with toter home.

Ted
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Old 11-15-2019, 05:20 PM   #10
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The race trucks use a purpose tire for racing. While they are limited to 100mph, the trucks are capable of 150mph and have no issues with tires at those speeds.
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Old 11-15-2019, 05:25 PM   #11
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The race trucks use a purpose tire for racing. While they are limited to 100mph, the trucks are capable of 150mph and have no issues with tires at those speeds.
Yep. That's correct.
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Old 11-15-2019, 05:40 PM   #12
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Going back to what the OP initially stated, understand that like TJones said you already have a hot rod of a bus. If you want to get into the 400-500 horsepower range, I don't think a C7 or Cummins 8.3 is going to cut it. That much HP is going to put you into a 12+ liter engine which is like a big CAT, Detroit DD13 or Navistar that is classed for a semi truck. The downstream components are then upsized as well for class 8 use, meaning 10-13 speed transmissions which can handle 2k ft-lb input torque then a beefy driveshaft and most likely a 20k rated drive axle with a final reduction gear. The weight penalty for all that is going to be about 3-4,000lb more than your current powertrain so now you need to think about your suspension to carry the weight and reinforcing all the frame mounts to handle the weight and the torque loads. By the time you've done all of that, you could have just bought a bus that was designed to do 80mph in the first place.

And speaking of which, the issues of brake and tires and such has already been mentioned but there's also a little matter of basic aerodynamics. That big metal brick doing 80 isn't by any stretch of the imagination cutting through the air - its slamming into it like a brick wall! Even if you get your rpms down you're still really now doing much more than burning fuel to get there a few minutes sooner. In semis every 5mph over 55mph is basically half a mile per gallon lower fuel economy. If you really need to be there faster then be prepared to dig deeper into the wallet for it. There's also a safety factor that comes with nearly zero aerodynamic coefficient and excessive speed. If its not a tire blowout it could be that unexpected crosswind coming down the hill and now you're going too fast to keep control and you're barrel rolling down the highway.

Basically I think your goal should be regear the differential to get your rpms down in the sweet spot for that engine at a reasonable speed and you'll have enough headroom to pass when its necessary. Just my two cents.
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Old 11-15-2019, 06:12 PM   #13
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Doner Engine

If you want to keep your bus look at buying one of the many wrecked motor homes, they typically have the highest power offered by an engine manufacturer such as the ISC/ISL from Cummins, they top out at 450hp, the ISX15 goes to 625hp. You could also look for ISM doners in older RV's

The DT570 can go to 400+ which you can make from swapping DT466 crank and I530 Pistons or something like that.

With the doner RV you would get the engine, transmission, brakes, possibly disc brakes, and the other beefed up chassis parts.

Im all about turning up an engine so you dont have to work it so hard. Ive got my DT466E getting turned up, larger injectors, larger turbo, higher tune, larger intercooler, water/meth injection. it does pretty good, I can pull an 8% grade at 50mph loaded with 1250 EGT, not too bad.
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Old 11-15-2019, 07:36 PM   #14
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This?

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Old 11-15-2019, 07:42 PM   #15
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Quote:
Originally Posted by EastCoastCB View Post
Bout the same as a bus. I heartily support folks doing this! I want a toterhome some day. I'd love a Pete.
If you aren't familiar google toterhomes and skip over the brand new super expensive stuff.
It would certainly tick off all the boxes. Horsepower, brakes, fuel mileage, driver comfort, under-stressed drivetrain... I have operated KW and Pete conventionals and liked it, I liked Volvoís a lot too. They had metal double wall cabs that were solid like nothing else. That made them very quiet going down the road and quiet for sleeping when parked. And itís no problem getting the engine you want. Caterpillar, Cummins, Detroit, Volvo, except that itís some kind of faux paw/heresy to have a Detroit in a Pete, I think.
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Old 11-15-2019, 08:41 PM   #16
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Quote:
Originally Posted by FamilyCircus View Post
If you want to keep your bus look at buying one of the many wrecked motor homes, they typically have the highest power offered by an engine manufacturer such as the ISC/ISL from Cummins, they top out at 450hp, the ISX15 goes to 625hp. You could also look for ISM doners in older RV's

The DT570 can go to 400+ which you can make from swapping DT466 crank and I530 Pistons or something like that.

With the doner RV you would get the engine, transmission, brakes, possibly disc brakes, and the other beefed up chassis parts.

Im all about turning up an engine so you dont have to work it so hard. Ive got my DT466E getting turned up, larger injectors, larger turbo, higher tune, larger intercooler, water/meth injection. it does pretty good, I can pull an 8% grade at 50mph loaded with 1250 EGT, not too bad.
A lot of good ideas from several of the posts above. A lot of options. About three months ago I had a chance to buy a 2001 international All American Bluebird with the 8.3 Cummins. If I remember correctly it had about 200,000 miles on it and it was said to have a bad radiator. The seller was asking $1500. It started and ran, didnít seem to have much blow by, but I wouldnít of been able to test the transmission, apart from maybe driving it around the block . That would be my swap package. Everything in one place.

As far as horsepower goes, I donít see why it would be too difficult to get 400 hp - 500 hp out of an 8.3. There are kids in every town in America Squeezin 500 hp out of the 5.9 Cummins. Granted, itís not the same as 500 hp out of a large displacement, 12l or more, commercial truck engine, but Iím not looking to haul 80,000 lbs and run 125,000 miles a year. The current crop of one-ton 3500 class pickups from Ford, GM and Dodge Ram are all putting out around 400 hp and they can be speced out to have gross weight well above the 36,000 gross on my bus. I know that the Allison 1000/3000 is capable of much more than The bus builders, and even Allison themselves are willing to admit with a little preparation.

Let me state it one more time. I am not looking to become a super speeder. I just completed 20 years without a ticket on my record. I hate tickets. I just want to be comfortable with pulling passes in my beloved Colorado I want to be able to pass slow-pokes on the two lanes without that white knuckle sensation that you get when you hope you havenít made a big mistake by stepping out into the passing laneAnd I donít want to have to hold my accelerator foot flat to the floor to run at 75 miles an hour.

My next step with my current bus is to get it in to do a warrantee download from the ECM. That will confirm my engines current rating status and engine family group. If I have the engine that I think I do, I should be able to get Caterpillar to turn it up to 360 hp. It already scoots pretty good in the lower gears. I am fairly surprised at how quickly it moves from a standstill. I donít even know exactly what the ratio is in the differential. That is something else I hope to learn. Maybe I will find out that I have enough on the low-end to justify a taller differential gear. On the other hand, I have heard that the C7 is not a good hill climber, that it has a tendency to overheat on long grades. I donít know if itís true and I donít want to find out.
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Old 11-15-2019, 08:57 PM   #17
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This was me two days ago. 78 mph indicated translates to 74 - 75 actual. I can squeeze another 5 mph out of it, but it really seems to be pushing it more than I am comfortable with. Boy-howdy does that passenger door flap and rattle and leak air where I’m going down the road like that. It’s high on my list of things that should be fixed. The driver seat has got to go too. Class eight trucks have had much nicer seats for a couple decades. I will have to remove that barrier between the passenger seat directly behind it so I can install the new seat with some more legroom

A lot of dust on the instrument cluster, and everywhere else because the bus sat for a year in what is basically on open lot in the desert.

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Old 11-16-2019, 07:36 PM   #18
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Quote:
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I have been considering getting out of buses entirely and doing something with a class 8 road tractor. I wonder how it would be to get insurance for something like that.
There have been a handful of outfits building RV's on class 8 truck chassis. As long as you can register it as an RV you are good in MOST states.

Google "Kingsley coach" They are one of the commercial outfits building them.

I have been in three "homebuilt" units and if I ever hit the lottery I am going to build one.
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