Hello all,
I am writing a research paper for my physics class on the effects the Tier 4 emission requirements have had on the thermodynamic efficiency of the diesel engine. In short, other than the new engines putting out less emissions, how has the diesel engine changed from say twenty years ago.
I have been to all the manufactures and all I can get from them is that they are meeting the requirements better than their competitors. (if I can get that much from them.)
I am hoping that any of you that have knowledge in this area can point me in the direction of finding information on this subject that I can cite in my paper.
Thanks in advance for any and all information you can give me.

 

The engines twenty years ago were mostly all mechanical, the only one I know that was electronic is the Detroit Series 60 12.7. Most of them got better fuel economy than the new ones, and were more reliable. The downside with the new ones is reliability. Anything minor will cause you to camp on the side of the road. The old ones had their problems but not as many. The engines today run hotter to cleanup the exhaust. Dpf's and EGR are mounted to all of them and I think they all have vgt turbos on them to. Somehow they burn twice as much fuel and produce half the emissions. Performance wise the new ones are better to mod because of the ecm can control fueling,boost in a more precise way, making more power cleaner. With the old ones smoke was usually a byproduct of power or bad tuning. Basically the new ones still work the same way but its all the stuff bolted to them that's changed. My honest opinion is if its an engine thats electronic (1998+) its a pos. Not trying to offend the guys with newer trucks but everything that rolls into work is always a newer vehicle.

 

Thanks for the info. Didn't engines back then, pre 1990s, run at about 180 degs? What do they operate at now?

 

Most of them are closer to 210 now.

 

Thats what the new stuff at work runs. Also if you let them idle in cool weather for 5+minutes the temp quickly drops to 120-140f, also to help emissions. Another thing is that fuel injectors shoot more than once during combustion, 3 or more times, to reduce noise and pollution. Most dpf equipped engines have a 7th (or 9th if its a v8) injector to shoot diesel before the dpf to raise the temp to 1000+ idling so it can burn off soot in the filter. The old engines would run around 300 idling and in cold conditions might have diesel slobbering out of the stacks. The materials in older stuff has less technology in them too. All pistons would melt at 1250 unless they were iron like some 2 stroke Detroits. Today they can with stand higher temps, for example the 6.7 Cummins can run at 1350 all day and not harm it and the TDI VW can see temps to around 1600 before damage occurs. These facts are in random order but i'm typing them as I think of it.

 

Thanks guys, this is the kind of information I am needing.
What has happened to the MPGs of old vs. new?

 

You really have to give us an idea of what "diesel engines" you are talking about. There are so many sizes, displacement, configurations that its just about impossible to compare them all in one fell swoop.

Can you give us an idea of the class of diesel engines you are talking about? pick up engines? Over the road truck engines? medium duty engines?

 

The short answer is I don't know because I don't know enough about todays engines to say for certain. I can look at them all as long as I compare one type of engine against the same type of a newer model. I hope I am not being too vague.
Thank you guys for bearing with me and my ignorance.