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Old 01-12-2024, 09:03 AM   #1
New Member
Join Date: Jan 2022
Posts: 2
545 conversion swap

I have a thomas bus with a vp44 24v Cummins with only 50k on it, was an office. I want to use the engine /trans for a smaller vintage rv build. Definitely not the 545 trans. I feel like I have 2 main questions that will come from the same knowledge base.
I like the packaging with cruise and high idle and more, but of course want a lock up converter, and at least one od.
Am also concerned about how many hp this can be tuned to.
So a bang for the buck trans swap is of interest, i see 1000 - md3060, too many options to make one plan. The physical swap is no problem, but I want a plan that makes sense for shifting and turning.
What I have now has a shift lever on the dash.
But I really would like someone to verify that I can at least get 300hp out of it, preferably a little more.
Little 10,000 lb rv but will pull a trailer. Would be happy to do compound turbos to make the most of the fuel available.
Too many questions?? Thx!!

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Old 01-12-2024, 10:13 AM   #2
Bus Geek
Join Date: May 2014
Location: West Ohio
Posts: 3,752
Year: 1984
Coachwork: Bluebird
Chassis: International 1753
Engine: 6.9 International
Rated Cap: 65
I hope you didn't buy this. You'd have been money ahead getting the allison you wanted in the bus you wanted vs buying the transmission and pieces after the fact.

IIRC isb with the HO vp44 could have been had at 300 hp behind motorhomes, and the 2500 allison that's commonly found mated to them is rated at 300hp in motorhome service as well. To get there, we'd have to know what your current HP level is. Being a bus, you likely have the SO vp44, which is capable of more power as well. Might have to change heads/pistons/manifolds as well as injectors. FWIW That generation ISB only used hx/hy35 turbos with all power levels. Turbo upgrades are a good idea regardless, you don't need twins, just something more efficient then the hx35. Even an hx40/35 hybrid would be better. Best would be to go with something like an s300 from borgwarner.

Banks had some offerings to boost power on these well past what would be usable, I wouldn't though, as longevity suffers substantially.

Before you do anything with this, you have to do something with the lift pump, as they're marginal as is in bus service.

What would I do? Sell your bus as is, and buy one with the transmission you want. Even if you got this for free, you'll still likely be money ahead selling this and getting the engine/trans you want in one shot.
My build: The Silver Bullet
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Old 01-12-2024, 10:20 AM   #3
Bus Geek
Join Date: May 2009
Location: Columbus Ohio
Posts: 18,909
Year: 1991
Coachwork: Carpenter
Chassis: International 3800
Engine: DTA360 / MT643
Rated Cap: 7 Row Handicap
you can get a 1000 built to handle insane amounts of power.. mine is built to handle 500 HP / 1000 ft lbs of torque.. I have it behind a 350 HP 7.3 and havent seen any ill effects.. i get solid quick full throttle shifts in the power band..

an SAE3 bell 1000 will bolt right up to where you take a 545 out. the converter offset, bolt patterm, bell bolts, all the same. (be sure you are not using a GMC bell allison 1000).. I probably wouldnt put 300 HP up against a stock 1000.. I spent coin and had mine built (suncoast out of florida built it 7 years ago).

you can see if your ECM has a J1939 data link on it.. if so then you could run a J1939 medium duty TCM which gives you full integration from engine to trans.. I believe most of the 24 valves do.. (im more an IH guy than a cummins guy so Im not 100% sure).. you might need to use insite to enable it and then pin it from the ECM.

TCM's if you want 6 speeds (recommended).. then youd want to have a 2006+ trans built and run a 4th gen TCM.. my TCM is EFIlive tuneablke and came from transmissiontiner dot com. I have tuned various transmissions for years. a base program from them will get you 90% there.. I wanted mine to integrate 100% so i invested in learning to properly tune an allison and get it where i wanted.. and have the EFIlive software / device..

I have full cruise control integration as well as a couple shift schedules so i can disable various modes if I desire..

an allison 1000 can be built with a Parking pawl so if you want to have the convenience of shifting to 'P' you can have it.. the parking Pawl is rated for i believe 30,000 lbs on a 3% grade. I have it on mine but have never gotten around to installing the shifter with a 'P' that I bought..

there are all kinds of shifters you can get.. if you dont care about a 'P' you can use a 545 shifter.. the gates are set at the same geometry and will work just fine.

while a 3000 is a much bigger heavier duty transmission,. there is much less aftermarket performance support for those vs the 1000 which because of the high performance duramaxx guys has a lot of aftermarket parts and shops that will build them, as well as programming aids. this is one reason i chose it, im happy with my choice
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Old 01-12-2024, 11:02 AM   #4
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Join Date: Jan 2022
Posts: 2
Great to hear guys.
I have very little in this bus and definitely could consider selling what I have for a profit.
I normally do dodge trucks and have a couple, one at 700 hp with a 47re, the recipe id go if I can’t meet my expectations for this.
I have no concern about the head and pistons, or longevity even at 600 hp, I also can’t imagine that a cummins could have injectors not capable of 300, but it’s possible and I don’t mind getting a better set.
I can check my current hp, but I am unsure of how.
I fully intend to use AirDog for a lift pump, thats also the biggest vp44 killer in the trucks too.
I will check the j1939, but ill have to look up how to recognize it.
On trans building and pcm / tcm purchasing, ill just have to see how it ads up, if too much I could have the 500+ hp recipe id prefer and do everything else stand alone, and like was said earlier, sell the current stuff.
I have a ve pump engine too that would make 450 really easily.
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cummins allison md3060

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