To "delete" or not to "delete"

campigloo wrote:
Shinerbock, I have really learned a lot from your posts. Thanks for hanging in. I have a 2012 6.7 Cummins. I don't like the smoke I see from most deleted trucks. I don't need more hp or torque. I have a limited understanding of the EGR system. My question is, how is returning oxygen depleted hot air back into the combustion chamber a good thing? Is that what happens or am I missing a lot of what is happening in the system? If I block that part of the system, does it have detrimental effects on the rest of it? Thanks, hope you don't mind the brain picking

EGR works by limiting combustion temp. The lower the temp the lower the NOX output. That's why on a high state of tune (clean burn engine) NOX are sky high. This is why people think that high compression race engines are clean because they burn so clean and are at a high state of tune. It's just not true at least for NOX.

Another thing people get confused by is they relate amount of gallons of fuel burned to how clean an engine is. Again, not true. I can run an automotive engine with all the smog equipment on it and run 10's of gallons of gas through it or I can run a gallon of gas through my lawn mower and it will put out more pollution. Counter intuitive? Yes, but the truth none the less.

Personally, from a mechanic standpoint I hate EGR on diesels. On a gas engine I have no problem with it. Diesel is a different story. They really can make a mess out of the engine and I hate dealing with that.

Again, it's all a tradeoff and balancing act. Fuel burn vs clean air.