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Old 11-27-2020, 04:54 PM   #1
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Tuning up 250HP Cummins

I am going to call about a 1997 Monaco Baron II that is 34'.
Owner lists it as having 250HP Cummins. NADA say it came as 300HP or 325HP.
If it is only 250HP how easy is it to get to 300? I need to tow my Jeep.
How can I tell for sure what he has?

I want to know more before I call so I can ask the correct questions.
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Old 11-27-2020, 06:49 PM   #2
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Ok for that vintage of coach ,a 250 HP Cummins could be a 5.9 L engine and the higher HP could be an 8.1 or 8.3L so you'll need more info on the engine size .

Also not all coaches will be equipped with a transmission that will handle a higher HP engine . You'd want to know the coach has an Allison 3000 ( 3060MH ) six speed, before proceeding.
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Old 11-27-2020, 06:53 PM   #3
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Ask for the engine serial number and give Cummins a call.

Cummins 800-286-6467

If 8.3 (C engine) it will have a LOT more torque than the 5.9 (B engine) and would have the Allison 6 speed 3000 series transmission (a good thing).
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Ex: 2003 Alpine 38FDDS. Ex: 1997 Safari Sahara. Ex: 1993 Foretravel U240
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Old 11-27-2020, 06:53 PM   #4
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250hp in a 97 Dynasty , I dont think thats right for an 8.3
95 Monaco Crown Royale
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Old 11-27-2020, 09:46 PM   #5
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It says it is on a Roadmaster chassis with airbag suspension and it does not state what transmission. Thanks for all the pointers. I will get more info when I call.
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Old 11-28-2020, 09:50 PM   #6
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I didn't look up specs again but listed was 300 or 325hp 8.3 will have 3060 trans that's good for 400-450 hp but limited to 1250lbs torque. I don't think 5.9 was available. If 300hp the power to weight and low end torque is good you may be able to bump that up even. If your interested and good deal go see it.
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Old 11-30-2020, 09:59 PM   #7
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A 1997 Monaco Dynasty should have a Cummins C8.3L mechanical engine and an Allison MD3060 6 speed transmission. The mechanical engines are pretty easy to turn up by rotating the fuel plate. You just need to be careful not to exceed the cooling system capability.
Depending on how heavy you load the coach and how heavy your Jeep is it should tow it. It will be more difficult in the western US in the summer heat.
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Old 11-30-2020, 10:16 PM   #8
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The 1997 Monaco Dynasty has a C8.3 300 HP(12 valve) Cummins engine. the 1998 has an ISC 8.3 330 HP(24 valve) engine.
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Old 12-01-2020, 09:46 PM   #9
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I am always amazed at the amount of information out there if one just asks.
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Old 12-02-2020, 10:27 PM   #10
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A 34' motorhome with an 8.3 will haul a jeep without breaking a sweat.

If you adjust the pump for power, you will want to make sure you install a pyrometer first.

It most likely has the 12 valve 8.3C and the following are modifications/ adjustments you would potentially want to do:

1. Install boost and pyrometer gauges. This is mandatory before anything else!

2. Adjust fuel plate and AFC cover forward to allow more fueling. Modify or install a modified/after market fuel plate if desired.

3. Adjust star wheel which allows fueling to occur earlier (at a lower boost).

4. Install a 3k governor spring kit. Stock springs start pulling fuel pretty early (2200rpm or so), and this makes a big difference in drivability.

5. Install an adjustable waste gate and set it to open at 30psi.

6. Install a larger diameter exhaust and/or free flowing resonator. The stock mufflers are restrictive and heavy. The exhaust noise is not appreciably increased. It may help power, but the biggest reason is to help lower EGT's

7. Pressure test turbo piping to identify and eliminate leaks. You are likely to find several. Each leak is wasted power.

8. Inspect the airfilter and replace if necessary or in doubt of the age. Also inspect all connections for holes or leaks from housing to the turbo.
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