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Lakota traveler
New Member
4 Posts |
 Posted - 05/24/2011 : 5:19:33 PM
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Wow, I found a huge source of information. I have a 36' HMC motorhome. It is powered by a 460 gas engine and the last trip gave me 5.6 MPG. Enough I said to wife and bought a '93 Cummins/545 Allison. It has 26K on a major rebuild. I have 19.5 tires/wheels that are 33" tall. The engine came out of a Blue Bird bus with 22.5 tires.
The engine is rated at 190HP. I have been told by two Cummins guys that it can be turned up to 225HP. The 225 rating has been used in boats for years now and is a good engine for medium sized boats in the 36' to 48' class.
I understand I have the best fuel pump for this HP change.
Now, my question. What RPM should I shoot for say at 60MPH. Should I make the HP rating higher before changing ring and pin?
The coach is on a Gillig chassis. Air ride suspension. Did I make a good decision on this engine? I am not into computers and like the mech. fuel pump etc.
I would like to have an OD transmission. Is there a non computer model available?
Thanks in advance for any help you guys have, Don |
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Wolf0r
Top Member
USA
2181 Posts |
Posted - 05/25/2011 : 12:45:06 PM
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| Have you checked to see if an adapter is available for your stock transmission? That would save you a lot of fabrication. |
“The good thing about science is that it's true whether or not you believe in it.”
Neil deGrasse Tyson |
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Lakota traveler
New Member
4 Posts |
Posted - 05/25/2011 : 6:10:27 PM
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Thanks Wolf for the reply. The 460 has a C6 with a Gear Vendor OD. The 5.9 has a Allison 545 4 speed trans and I want the reliability of the Allison.
As far as the installation Blue Bird mounts fore and aft will bolt in with some holes drilled.
I need a air compressor gear drive and a power steering pump that mounts to air pump/ gear drive. These I believe mount to engine on the driver side. I also need a A/C pump to complete installation.
My main question is adjusting pump up to the 225 rating. Is this reliable? Also what is a good RPM to cruise at? I will adjust rear end ratio to that RPM curve.
I think I am stuck with a 1-1 ratio because the OD units are all computer operated. Bummer!
By the way, this engine will be mounted in the front. The only drawback is the noise and the dog house right in the way of the drivers seat....Oh well, thanks again, Don |
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partsman_ba
Administrator
United States
377 Posts |
Posted - 05/26/2011 : 09:44:13 AM
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| You might get better info on a motorhome bulletin board - not a whole lot of gas to diesel swaps going on in the school bus world, and I'm not sure that (at least our) state regulations will allow HP adjustments. |
"Growing old is mandatory. Growing up is optional." |
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Jake
Top Member
USA
3527 Posts |
Posted - 05/26/2011 : 12:04:35 PM
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Here's a good motorhome/ school bus conversion forum:
www.skoolie.net |
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matts4290
Advanced Member
224 Posts |
Posted - 05/26/2011 : 4:22:01 PM
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If you want to bump it up in horsepower, I recommend adding an exhaust temperature gauge. I'm sure you'll be able to find out how to bump up the pump on the cummins forum.
For RPM, I've heard that cummins run most efficient at either 1900 or 22-2300.
My Blue bird runs about 2250 at 55 with the same set up and 11R22.5s with a 4.33 rear end.
Remember to watch your gear ratio. Gas engines run higher RPMs than a diesel. |
We can't all be conventional!
http://www.youtube.com/user/matts4290 |
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C.HARDY
Advanced Member
354 Posts |
Posted - 05/26/2011 : 5:15:56 PM
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| There is a mechanical OD transission. I believe the 643 has OD (but I may be wrong) A 4.33 would still probably be too low with 19.5 tires. As far as HP 190 should be good for a motor home, they are a whole lot lighter than a bus and 190 pulls a bus fairly good other than tall hills. If the engine runs good I personally wouldnt adjust it. |
"Hardybusman" |
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Lakota traveler
New Member
4 Posts |
Posted - 05/26/2011 : 7:09:32 PM
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| Thanks for the good information. I will check these sites out. My coach weighs in at 21K Thanks again, don |
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C.HARDY
Advanced Member
354 Posts |
Posted - 05/27/2011 : 12:01:24 PM
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| Wow that things heavier than I thought. Most buses are 12-15k. |
"Hardybusman" |
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1993 Cummins 5.9 TA Motorhome swap
