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Author Topic: looking for information on converting a 892 to cummins big cam in a 83 prevost  (Read 2553 times)
jray
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« on: November 14, 2013, 08:59:43 PM »

new to this board is this possible? thanks.
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Jim& sherry Pagnotta
 83 prevost 92/754
Priest river Idaho
kwidd
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« Reply #1 on: November 14, 2013, 09:15:43 PM »

It can be done but it is a very big job. I installed a Cummins M11 in my 81 lemirage. The big cam is to long.
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jray
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« Reply #2 on: November 14, 2013, 10:08:47 PM »

thanks for the comeback  are you happy with your changover?
 did it fit in your engine compartment? how did you cool it?
   thanks jray.
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Jim& sherry Pagnotta
 83 prevost 92/754
Priest river Idaho
luvrbus
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« Reply #3 on: November 15, 2013, 03:15:08 AM »

The tag axle is the big issue Ken installed a 14L 60 series in his Prevost he can tell you the in and outs it takes a while and a few bucks

 I looked at doing one for friend and decided it was too much work while the old 855 was a good engine doing that much work I would look into a more modern up to date engine JMO
« Last Edit: November 15, 2013, 03:35:09 AM by luvrbus » Logged

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Jon
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« Reply #4 on: November 15, 2013, 04:03:30 AM »

The issues are going to be the length and dealing with the tag axle. Even Prevost couldn't install a late model 6 cylinder until they had the availability of the 6 speed Allison transmission because the 5 speed used prior to that transmission in combination with the 6 cylinder engine was too long. When they did make the change in the mid 90s they had to modify the tag axle among other things.
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Jon

Current coach 2006 Prevost, Liberty conversion
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Hard Headed Ken
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1988 Prevost Angola Conversion Repowered With 14L Series 60 & Eaton Ultrashift


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« Reply #5 on: November 15, 2013, 04:55:59 AM »

As stated, the length is the problem combined with the diameter of the Allison 6 speed. I used an Eaton Ultra Shift because it's more of an oval shape and would go over the top of the tag axle. I still had to notch the tag axle to provide clearance when all the air was dumped from the suspension. I had about 1000 hours in my swap and I have most every piece of equipment needed to do the swap. I think an ISM would a little easier but you're still in for a tremendous amount of work. Take a look at some of the things I made.  https://www.youtube.com/watch?v=oxAFFBcoTQI

Ken
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luvrbus
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« Reply #6 on: November 15, 2013, 05:04:34 AM »

Prevost got together a lot quicker on the H models for some reason you run across 92 models of the H series with 60 series

 I was told Prevost never used a 11.1 but I bought a 92 model H that had a 11.1 series 60
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« Reply #7 on: November 15, 2013, 06:56:58 AM »

If you're converting from a 8V-92TA, cooling another engine will not be an issue since the 8V-92TA is probably the hardest engine to cool. The easiest would be a Cummins M11/ISM rebuilt to RV spec of 500hp @ 1550lb/ft torque with an Allison world transmission.
If you notice on Prevost (not sure of the model), you can easily tell when they switched from 8V-92TA to Series 60 since the rear overhang is noticeably more with the Series 60.
But-like the Cummins big cam/N14, ISX15 or Caterpillar 3406/C15/C16 or Series 60, these are all what is called a big block. Stick with a medium block engine (still more then enough power) like the Cummins M11/ISM/ISX12, Caterpillar C12. Don't use the Mercedes 4000-it is a warmed over Series 55 that never worked right. Good Luck, TomC
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Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
RJ
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« Reply #8 on: November 15, 2013, 08:37:49 AM »

new to this board, is this possible? thanks.

Anything's possible if you throw enough cash at it.

OTOH, if it ain't broke, why fix it?

FWIW & HTH. . .

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RJ Long
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Fresno CA
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« Reply #9 on: November 15, 2013, 09:24:03 AM »

Have  to agree with RJ here even if it is broke; Clifford and others have managed to get over 7mpg out of the 8V92 with out the headaches of the swap. I know the challanges first hand.  you take care of the old beast and she will be there for the long haul.  You will have to go to the mid 90's prevost around 94-95 to get the independent  rear tag axle to have enough clearance for a 60 series or Cummings. I had a 89 now a 98 and both tags are different. One had 8v92 the newer 60 serries---Ken had the older tag and was a real challenge and mine required no mods at all for the autoshift.   Bob
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Bob@Judy  98 XLE prevost with 3 slides --Home done---last one! SW INdiana
Hard Headed Ken
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« Reply #10 on: November 15, 2013, 11:00:49 AM »

Some of the middle 90's with the Series 60 had a solid tag axle but it was over the top of the transmission like an upside down U. Before that they were like mine, solid axle that when under the transmission. I'm pretty the over hang on mine and a 45" entertainer chassis with a Series 60 is the same. Prevost made the wheel base slightly longer on the 45' entertainers for a better ride. A 45' motor home chassis has a slightly shorter wheel base causing the extra overhang which allowed a slightly shorter turning radius and a 40' motor home chassis with the Series 60 has the same over hang / wheel base has my 1988. I'm speaking of the XL chassis.

Ken
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Don Fairchild
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« Reply #11 on: November 15, 2013, 01:10:02 PM »

another thing you need to think about is weight, an 855 cummins weight's 4400 lbs. and the 8V92 2300 lbs. My 8V92 DDECIII with overdrive Allison gets 8.4 towing and 8.9 with out towed.

Don
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wg4t50
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« Reply #12 on: November 15, 2013, 03:11:27 PM »

I installed the12V-71 in the MC7 with the RT910, it proves you can do anything if you want.
My largest issue was a very special short driveshaft with slip joint of 9.5" center to center of u joint in mid position. A crazy looker due to very short splines, but about 8 " diameter, they gotta get the meat in it sonewhere as the splines were about 2.5" long.
With a welder, grinder, drill and some thought, you can make anything and have it work great.
By the way the 12V-71 is about 3450 lb, the 855 is about 2700 lb, then add options.
I would not do it again, with better choices, the ISM  Cummins Series is smaller, lighter and a lot more fuel efficient, Little less hp, but am not in such a rush now. Grin
Dave M
« Last Edit: November 15, 2013, 03:22:54 PM by wg4t50 » Logged

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TomC
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« Reply #13 on: November 15, 2013, 07:13:54 PM »

Don's a bit high on the weight of the big cam/N14. They tipped the scale at 2,900lbs (without trans). The heaviest engine now is the Cummins ISX15 at 3,100lbs. The 12V-71 weighed in at 3,200lbs-3,500lbs with turbo and aftercooled. The Cat 3408 was 3,500lbs and the Cummins KTA 3,800lbs.

The Cummins ISM is right at 2,100lbs, or about the same as a 6V-92TA, with the Cat C12 a bit more.

Also, keep in mind, the 8V-92TA (along with 6V-53TI) are still being made for the military. Good Luck, TomC
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Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
jray
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« Reply #14 on: November 15, 2013, 09:43:26 PM »

thanks all who comented to this post. I think I will go with the ims or the imx  I would like to stay mechanical as I am an old guy and like simple want the HP for fuel mi. thanks to you tom you helped me last
year when I converted the 6 speed to the 754. should have done this then but I don't do simple.thanks again. Jim.
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Jim& sherry Pagnotta
 83 prevost 92/754
Priest river Idaho
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