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 2/28/2003 9:34 AM
 
We are going from a 5th wheel to a diesel motor home. We have narrowed it down to two. My question is "Does the 257 Cummings and enough power or do I need to go to a 300. We are part-timers, several long trips & many short ones in a year. Also, can the 275 be up-graded? Thanks for your help
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 2/28/2003 2:43 PM
 
There are many motorhomes out there that produce less than 275 hp. We have been fulltiming in a motorhome with a 275 hp Cummins for almost 4 years. The key is the power to weight ratio and the torque produced by your vehicle. A year or so after we purchased ours, the engine was uprated to 300 hp to meet Federal Nox ratings. It really didn't improve much and actually decreased the miles per gallon. We could have ours uprated, but the only benefit we would accrue would be to put some cash in someone's pocket for doing this. Current models of our rig are running with a 330hp CAT. Those rigs get about a 1.5 mpg less fuel economy than we do. We have been across the country several times, to Alaska and crossed the Rockies through the Eisenhower tunnel at 11k feet twice. We have had no problems with our 275hp engine and get a solid 10mpg. I wouldn't worry about the difference between a 300 and 275 hp engine. John Veach www.TheRollingHome.com

Libby and John and RV the CAT www.TheRollingHome.com 1999 Fleetwood Discovery 37V Unit 38 Fort Clark Springs Brackettville, TX towing a 2005 Chevy Colorado Z71 4x4 Click here to see our current location
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 2/28/2003 4:05 PM
 
I'd like to echo what John said. I drove a 37.5' Discovery DP for 3.5 years. It had the 275 engine. About a year or two ago, Cummins "uprated" the 275 to 300 HP. (If you take a look at the HP and Torque curves, the extra 25 HP was achieved by boosting the max RPM. Not an RPM that we drive at very often!) The reason for the uprating was at least partially because the diesels are in a "horsepower race". The Discovery had no problems with any grades or mountains that I encountered.
I found the 275 to be a great engine. Gave me a solid 10.3 MPG towing a Suzuki toad. No failures or breakdowns. Never used oil. Maintenance required only once a year.
I would not hesitate a moment in buying a coach with a 275. Regards,
Fred White

Regards, Fred White Polk City, FL
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 3/3/2003 7:35 PM
 
The 275 HP Cummins is a ISB engine, the same one used in the dodge PU, it has 6.9 liters, a good engine. The There is also a ISC 275 HP Cummins this one has 8.9 liters. and can be programed up to 330. The 8.9 has a lot more torque so if you have a heavy rig you should want the ISC. I have a ISC in a 41 footer,I pull a chevy van full of stuff and if I drive at 60 mph or lower I get 10.2 mpg, I have it programed to 300 hp. There is now a 2003 ISB 6.9 L that is rated at 300 HP, it still will not have the torque of the 8.9. hope this helps.
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 3/4/2003 4:26 PM
 
Just a quick comment on "oldman's" post. Cummins "B" block is 5.9 liters displacement, not 6.9. The mechanical version had ratings from below 190 HP to 230 HP. The ISB, or "Integrated Systems" electronic version, has ratings up to 300 HP. As I remember, the ISB 275 and 300 both had torque ratings of 660 lb-ft.
The "C" block Cummins is 8.3 liter displacement. The early "mechanical" C blocks were rated as low as 250 and later up to 300 HP. My DP has an ISC 8.3 Liter rated at 350 HP and 1020 lb-ft torque. Regards,
Fred White

Regards, Fred White Polk City, FL
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