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Old 04-06-2014, 08:34 PM   #1
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Engines and Exhaust Regulations - Post 2007

So around 2007, some regulations came in for diesel engines. A few years later, DEF and other regulations kicked in ...

So what are we dealing with when we buy a new coach with the newer engines?

Do we lose mpg?

Do we lose HP?

I'm guessing they're going to be more expensive to maintain?

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Old 04-06-2014, 09:34 PM   #2
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Actually the DEF engines get better mileage, run cleaner, with the same or more horsepower and torque. The service requirements for the SCR system don't start till 200,000 miles, most coaches will never see this mileage.

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Old 04-07-2014, 05:20 PM   #3
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I have a 2010 Cummins 340 HP. But it was made in 2009, therefore it only has the 2007 EPA stuff... no DEF. I get 11 to 12 MPG in flatlands between NC and Florida towing the Saturn Vue. I talked to a guy who had a 2011 model and he told me he got 14 MPG. I believe it.
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Old 04-10-2014, 09:27 PM   #4
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Originally Posted by cucotx View Post
So around 2007, some regulations came in for diesel engines. A few years later, DEF and other regulations kicked in ...

So what are we dealing with when we buy a new coach with the newer engines?

Do we lose mpg?

Do we lose HP?

I'm guessing they're going to be more expensive to maintain?
Yes to all the above, and add the big YES to the increase in cost just for the privileged of having them hang all the junk on the engines. Yeah, Cummins and the EPA swear the mileage increases and things are all rosy, but in reality, to meet the 2007 EPA requirements the engines were de-rated so badly that the mileage really went into the toilet. Now they give you a small part of that back at the high cost of all the trash they hang, and claim it's such an IMPROVEMENT... Just another line of BS. How can mileage increase when all the extra garbage they've added is in the EXHAUST STREAM---after the power has been extracted from the fuel to drive the engine and coach? The answer is that the engine has not been de-rated as much as it had in the previous iterations, but it isn't what the previous engines were before the EPA started telling us just how great their changes were.
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Old 04-10-2014, 10:51 PM   #5
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Another thing was it didn't matter what year the coach was but when the engine was built. My coach is an 08 with an ISX600 Cummins with no emissions. I don't know much about the emissions stuff other then a couple of trucks we have at work are international and they have emission problems every couple of months and I talked to the shop foreman at our local cat shop and he said they have problems with the cats with no consistency and no help from cat so I was just gun shy to even consider it. That said there are a lot of engines out there running fine.
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