What year did Emissions affect Cummins
Registered User
Joined: Aug 2010
Posts: 13
Likes: 0
From: Idaho
Model year 2004.5 with the "600" 325hp/600tq engine was the first with a cat, which I believe made it California legal at the time.
I don't know that the mileage really was affected much if any by the controls put in place at that time on that engine. My belief is, that came later. My opinion however is that this is when mileage hit it's peak and began to drop. This was also around the time Dodge was trying to step out with selling more Diesel trucks and believe is partially responsible for making them California compliant. I'm sure though that the government bean counters were sure to have had a large part in placement of the cat as well!
From that point in talking with people and doing some reading seemed to be where the mileages began to drop. I hear more people complain about the poor mileage they are getting from their new trucks than the great mileage they're getting.
Now to be fair though you might also argue that it wasn't specifically the emissions that impacted the mileage. Dodge and all the manufacturers were DEEP in the HP and Torque wars at that time. (Then came the tow ratings) Remember additional power is PRIMARILY made by adding more fuel and that lowers your economy! Each brand had to beat the other and there were some very impressive increases made to the stock trucks in the years since 2004. In the years prior to 2004 they were focusing on bringing the power up as well but primarily focused on making the engines quiet. Dodge dropped their noise level of the 2004 truck something like 65% from what it was a couple years prior. This is reaching a bit but keep in mind that the national speed limit was not increased to 65 mph until 1995. I believe many states didn't increase their state limits due to the federal funding they would receive for road assistance if they kept their average speed down and were only increased on true rural roads. So people's driving habits along with driving regulations might be now allowing higher speeds to be driven. This will dramatically impact mileage! I get 21-23mpg on hwy with my truck doing 60-62 but if I step it up to 70 my mileage drops to 19. (I'm just saying there might be something to think about there....lol)
So, this is primarily my opinion/interpretation from what I've read/seen and people I've talked to over the years. (In and out of the industry) If something isn't specifically correct feel free to blast away and or just correct me.
I don't know that the mileage really was affected much if any by the controls put in place at that time on that engine. My belief is, that came later. My opinion however is that this is when mileage hit it's peak and began to drop. This was also around the time Dodge was trying to step out with selling more Diesel trucks and believe is partially responsible for making them California compliant. I'm sure though that the government bean counters were sure to have had a large part in placement of the cat as well!
From that point in talking with people and doing some reading seemed to be where the mileages began to drop. I hear more people complain about the poor mileage they are getting from their new trucks than the great mileage they're getting.
Now to be fair though you might also argue that it wasn't specifically the emissions that impacted the mileage. Dodge and all the manufacturers were DEEP in the HP and Torque wars at that time. (Then came the tow ratings) Remember additional power is PRIMARILY made by adding more fuel and that lowers your economy! Each brand had to beat the other and there were some very impressive increases made to the stock trucks in the years since 2004. In the years prior to 2004 they were focusing on bringing the power up as well but primarily focused on making the engines quiet. Dodge dropped their noise level of the 2004 truck something like 65% from what it was a couple years prior. This is reaching a bit but keep in mind that the national speed limit was not increased to 65 mph until 1995. I believe many states didn't increase their state limits due to the federal funding they would receive for road assistance if they kept their average speed down and were only increased on true rural roads. So people's driving habits along with driving regulations might be now allowing higher speeds to be driven. This will dramatically impact mileage! I get 21-23mpg on hwy with my truck doing 60-62 but if I step it up to 70 my mileage drops to 19. (I'm just saying there might be something to think about there....lol)
So, this is primarily my opinion/interpretation from what I've read/seen and people I've talked to over the years. (In and out of the industry) If something isn't specifically correct feel free to blast away and or just correct me.
Record Breaker
Joined: Aug 2007
Posts: 2,283
Likes: 2
From: live oak, ca
all cummins are vairly similar in milage up to 07.5, anything prior is also a 5.9 engine, @ 07.5 the switched to the 6.7 engine, and also added the egr system, as well as the DPF wich includes a lot of other related parts and lessens the milage by qiute a bit
Champion
Joined: Feb 2005
Posts: 3,710
Likes: 2
From: Skagit County, WA
Removing DPF and EGR and doing a few other little tweaks will net you anywhere between 5-8mpg on average, putting it closer to where the 5.9 is.
I'm making ~420 rear wheel HP in my 6.7 and I get about 20-22 on the freeway between 65-70.
I'm making ~420 rear wheel HP in my 6.7 and I get about 20-22 on the freeway between 65-70.