Good morning, in this horsepower class of diesel engines there is still at times a visible exhaust trace from the engines exhaust.
Although the engines are cleaner burning than their earlier counterparts the Tier 4 emissions for this horsepower class is still not a (no visible emissions from the exhaust) as with the newer over the road trucks and some heavy equipment being manufactured today.
My wife and I occasionally watch trains at a location called Conpit on the Pittsburgh NS main line. If the trains are heading east which is up hill at this point on the railroad you can visually see the black exhaust being omitted from the engines exhaust.
These engines are usually traveling 45 to 50 mph so they are not at crawl where the lead engines are trying to get a consist moving from a dead stop.
If the sun is out and is low in the western sky the exhaust is even more prevalent. All these NS road engines are the latest and greatest as far as the Tier 4 emission goes.
For a diesel model train to smoke, I think MTH could have toned down the smoke output or make the smoke output appear when the engine sees a quick increase in speed or just randomly come on possibly sensing the amperage being pulled by the engine while traveling around ones layout.
Either way another program would have to be written and developed for the diesel engines electronics which is expensive for the manufactures.
This past holiday season we set up a layout at the Indiana Mall here in Indiana PA.
On the layout this year we ran modern MTH diesel engines and at times we turned the smoke units on and the visitors visiting the display seem to be impressed with the smoke output so it does have a visual affect on a person watching.
As mentioned earlier in this thread the smoke brings play and a somewhat realistic feature to a diesel engine that really has no visual motion and sound to go with the visual motion as with a steam engine.
As with all models with smoke if you don't want it to smoke turn it off.
Remember they are still (expensive) toys that allows us in this hobby to create our own little worlds !!!!
