[c36dash7]

Walter : I cannot make specific recommendations concerning this, although, having seen the most recent development with smoke emission, for Open Rails, this truly is a worthwhile pursuit.

Since Alcos tend to use lower grades of diesel fuel, the smoke generally was more abundant and thicker.

There is a "myth", though , about thick black Alco smoke, and usually , such occured when a locomotive had been idling away for an extended period of time, and cranking up the throttle ( when starting from standstill ) , this "burned off" a lot of carbon residue that built up .

Under normal and steady operation , the smoke emission was not much different than others of their era ( only a bit thicker, and more, say , "rounded" ...'-)

Jean Brisson growing up 3 miles away from Montreal Locomotive Works

[rdamurphy]

In addition to adjusting the max/min values, also try adjusting the stack width slightly. Wider will give you wider smoke, narrower will give you a more concentrated plume. And remember, the values are rather fine, so a slight change will make a big difference...

One thing you might try is to compare the values between the SD40-2 and the D9. The -2 has a tall thin plume, the D9, a short fat one. And remember, the exhaust width doesn't need to match the actual width of the exhaust to look good...

Robert

[railguy]

Here are some things to check and try. First, a lot of .eng files are written with RPM change rates that are the same for EMD's, GE's, Alcos. GE's and Alco's don't "spool up" as quickly because they are 4-cycle engines. I usually use between 18 and 25 for the RPM change rate for Alcos and GE's, around 30-36 for EMD's. For me, that makes both the smoke and sound more realistic. Second, for smoke, many .eng files are written with Minimum SmokeRate and SmokeMagnitude values that are too high--I set mine at or near 0.0. Idling engines usually smoke little, if at all when at idle. The best thing to do is to play with the Maximum SmokeRate and Magnitude setting until you get the effect that you want. As noted, changing the nozzle diameter is another variable to play with until a good effect is achieved. Another trick to "delay" the smoke effect for a second or so is to lower the "Y" value (the second parameter) in the Exhaust1 (or 2) line a tenth or two. That "buries" the smoke in the unit until the engine has spun up a bit in RPM.

There is no "one size fits all" trick. I even vary locos of the same class in one or more parameters, so they won't quite look or sound the same when they are lashed together. That's prototypical.

[c36dash7]

Walter : I believe you understand that all suggestions made so far, strictly have to do with some slight ( and very easy to do ) editing, of individual locomotive's engine files .

Not using Open Rails, I would not know if some settings, would allow to make changes such as you wish , that would only apply... to Alco's .

As suggested, also, some slight variety and randomness, between from one individual locomotive, to the next , would be most desirable , to avoid those "all at once" / "in chorus" , exhaust emissions, from 2 or 3 Alcos coupled together . I will try to dig up some early screenshots showing some really thick and black ( MSTS ) Alco smoke .

Jean Brisson

[c36dash7]

Walter : I was unable to find a specific screenshot, but turned up a few other ones, from my earliest days , in MSTS . Playing with some of the variables and parameters, as suggested by others, plus actually "making my own" ( smoke texture ), the following , for whatever it's worth, shows that it still is worthwhile to play around with the smoke effects , for Alcos. If you look carefully, you may note some subtle differences, between the first and second unit's smoke emission pattern , for a much desired level of randomness . Each of the locomotives had to be optimized, individually .

http://i271.photobucket.com/albums/jj143/c37dash7/BC%20RAIL%20action/Bag80001.jpg

http://i271.photobucket.com/albums/jj143/c37dash7/BC%20RAIL%20action/Bag80003.jpg

http://i271.photobucket.com/albums/jj143/c37dash7/BC%20RAIL%20action/Bag80006.jpg

http://i271.photobucket.com/albums/jj143/c37dash7/BC%20RAIL%20action/Bag80009.jpg

http://i271.photobucket.com/albums/jj143/c37dash7/BC%20RAIL%20action/Bag80013.jpg

Jean Brisson

[steved]

I have an old U-Boat with a stuck injector that puts out quite a cloud of smoke.
I use these parameters.

Exhaust1
(
0.01 4.877 -3.155
0 1 0
0.3

DieselSmokeEffectInitialMagnitude( 0.0 )
DieselSmokeEffectMaxMagnitude( 10 )
DieselSmokeEffectInitialSmokeRate( 0.0 )
DieselSmokeEffectMaxSmokeRate( 4 )

I think it looks pretty good.

Steve

[rdamurphy]

I did a huge post on exactly which .eng parameters do what and how they effect smoke in OR, etc... Be darned if I can find it now? :oldstry:

Robert

[rdamurphy]

Yep! http://www.elvastowe...post__p__124868

Robert

[EricF]

The problem with Alcos is that their smoke output is a function of turbocharger lag, so it's a non-linear relationship to engine RPM increase. Alco's turbochargers were notorious for "spooling up" slowly so that the fuel mixture ran too rich (causing the smoke) until the turbo could catch up to speed in the exhaust stream. For Alco behavior, the smoke output rate hasto increase abruptly and then trail off again more slowly to a lesser value with each change in RPM. You could try changing the "DieselEngineMaxRPMChangeRate" value to something larger, but that may cause unwanted changes to other performance characteristics in the .eng file if it goes too far off.

There are some other things going on in diesel engine combustion, especially in the older four-stroke diesels like Alcos. Fuel timing and mixture have a lot to do with smoke output; in the era of those old Alcos it was harder to manage with the mechanical fuel injectors of the era. Leaning the fuel/air mixture produces less smoke, but to achieve full more power from the engine, a righer mixture is needed. The downside is that a diesel will smoke noticeably before the mixture crosses the line and goes over-rich. In other words, more power means more smoke as a consequence. Alco was trying to squeeze every last bit of performance out of their engines, and tended to run closer to the maximum practical fuel/air ratio. Add in the turbo lag, and you get some pretty impressive smoke-screen effects. :unknw: