• Air inlet redesigned to block hot engine air from entering, reducing the intake charge by 30 to 40 degrees.
• Intake resonator re-engineered for increased airflow
• Engine cooling improved with new fan assembly and mounting fan shroud to engine for more efficient airflow through radiator
• Upgraded intercooler
• Upgraded exhaust valves
• Tailpipe increased to 4-inch diameter
• Improved sealing and gasket materials
• Oil-change intervals are now 15,000 miles (vs. 7,500 for competition).
• Holset turbocharger gets bigger compression side
• Switch to electronic control of wastegate
• Upgrades to exhaust manifold
• Revised intake ports in cylinder head
• New piston bowl geometry
• Different spray pattern from injectors

 

My Late 04 555 had / has a true 4" tail pipe on it..... Do the 03's and early 04's not have the 4 inch tail pipe?

 

What exactly was changed with the exhaust valves? Are they larger diameter or different material, or? What about the intake ports... how did they change? I'm guessing the injectors could cause bad MPG, but I would assume if they're changed to meet more stringent EPA, they'd be atomizing better, which SHOULD be better MPG not worse. So could any of these things be the reason for the poor MPG?

 

Hello Hoot

I'm a former Duramax owner as well. Got my 04 555 about a month ago. I choose the 555 after some research on the emission approach Cummins was using for the 04.5. I had posted this on thedieselpage forum back in February(http://forum.thedieselpage.com/cgi-b...c;f=3;t=007506). The main source I found discussing emission approaches was at http://www.epa.gov/otaq/regs/hd-hwy/1997frm/r97009.pdf


To sum up the study: Meeting NOx emissions can be done with the least impact to fuel economy using EGR (at the expense of oil contamination), with a higher impact to fuel economy using a lean NOx catalyst approach (without the oil contamination issue). Cummins is using the NOx catalyst approach with it's third injection pulse.

 

Good stuff TDIwyse.

I actually asked for the 600 when they were finding me a truck. They told me it was but when it arrived it was a 555.

So I had them knock another $500 off the deal and throw on a tonneau cover.

Hehe.... worked out for the better in more ways than one.


thejeepdude,

I don't know what exactly they did but it looks like many of the changes were for emissions but sold as performance.


Nitro71455,

My tailpipe is also 4". The muffler outlet is 3 1/2". The tailpipe adapts to it.

 

The 555 exhaust tailpipe is 4 inches.

The true 4 inch exhaust comes from the cast iron "turbo elbow" that goes from the turbine outlet to the downpipe (this is that part that is replaced when you get an exhaust brake). On 555 models, the elbow goes from the 4 inch turbo outlet to the 3.5 inches on the downpipe. For 600 engines, the elbow is 4 inches on both the inlet and outlet.

TDIwyse is correct, both the Duramax and 6L PS use EGR, the CTD600 does not. Again, the FE loss stems more from the retarded injection timings than it does from any post injection events.

Just because the combustion process leaves less unburnt fuel, doesn't necessarily mean you will get more BMEP for a given amount of fuel injected into the cylinder. Its all about when the combustion occurs that determines BMEP.

 

So what you are saying is you are reducing emissions by squirting fuel in after the combustion event has already done most of it's thing.

These days that's an aweful expensive emissions additive

 

Exactly what I found...... I just hacked the first 4 inches of tail pipe off and used the stock pipe with my system (banks DP, floPro muff, and 7ft of 4 inch straight pipe.... Worked like a champ, and optained the factory look from using the stock tail pipe.

 

So is the concensus that a timing box may remedy this? Has anyone tried the TST CR on 1/1 with an 04.5/600 and seen if it improves the mileage back to "normal" figures?

 

The study in the link above said that with either the EGR or lean NOx catalyst approach that timing of the main injection pulse did not have to be any more retarted compared to previous non-emission compliant engines. Now this study was generalized, and wether Cummins actually retards the main injection pulse compared to the previous 555 engine in its execution of the lean NOx approach I don't know. I had emailed Cummins about this issue back in February when I was researching this and did not get a specific reply (it was a canned, general response that was unhelpful to my specific question). I have also not seen any specific data to suggest the main pulse is more retarted than the previous generation engine.

Also, the study indicates the third injection even is used to keep the catalyst at the optimum temperature for NOx reduction. It indicated that the fuel consumption degradation was due to the post combustion fuel injection pulse. Again, wether this corresponds exactly to Cummins execution of this approach is still up in the air. I would imagine that being able to eliminate this third injection event with a software or hardware change would have a significant improvement in fuel consumption at the expense of more NOx output.

 

Sounds like a plan for the programmers. I'm sure that's on thier hit list.

Might even generate more smog to boot!

 

That's what I was wondering if the TST or any other box will do... guess not at this point... definitely seems like something they should come out with!

 

I might not have been this p*ssed if we had been warned about the fuel economy loss, due to emission requirements,.......instead of LURED into it by the higher HP/TQ claim.

 

dwhite
I couldn't have said it better! I too feel DC lied to us, but it might back fire on them once the word gets out. I have seen some people on these boards already backing away from buying a 600

 

Third injection event is MPG going out the pipe. Probably also is used a temperature modififyer to provide parameters for a high and low exhaust gas temperature. Want to bet they make some changes soooon. This is not a good engineering design for emissions control even though that is what they are using to flog the 600.

Fair number of people are staying away from the 600 for now. I am 1 of them.