These numbers are from a particular payware loco that I have that has some wonderful smoke effects. A good place to start, I believe... Note the numbers are in meters. DieselSmokeEffectInitialMagnitude( 1.5 ) = The height of the smoke at idle, or, in effect, how long the "particles" live before they go away. DieselSmokeEffectMaxMagnitude( 7.5 ) = The height of the smoke at full throttle. DieselSmokeEffectInitialSmokeRate( 0.7 ) = The amount of smoke at idle, think volume, or how many "particles" there are. DieselSmokeEffectMaxSmokeRate( 0.8 ) = The amount of smoke at full throttle, think volume. DieselEngineIdleRPM( 318 ) Engine Idle. DieselEngineMaxRPM( 904 ) Engine Governed rpm. For an EMD 645, this should be 900, not sure why Kuju used 904... DieselEngineMaxRPMChangeRate( 40 ) This is how fast rpm's change per second. For instance, if your at Idle, and hit Run 8, the rpms will increase by 40 rpms per second. In other words, how fast the engine "revs" up. The code recognizes when the rpms are rising or dropping and adjust the exhaust effects accordingly, to avoid "abrupt" changes and to simulate "no-load" conditions. All of these parameters, in addition to the following affect the smoke output: DieselSpecialEffects ( Exhaust1 = Only two exhaust outlets were allowed by the original KUJU code... ( 0.0 4.738 1.485 = the location on the model of the exhaust stack defined from the main shape's pivot point. 0 1 0 = Where the smoke is going. This is "straight" up at idle. It's a bit more complicated than that when moving, but basically it defines a fixed point within the train simulator "world". 0.1 = width of the nozzle in meters, in this case, the radius. I've seen nozzles that were 2 meters wide... ) ) Let me know if you have any further questions. One of the things I suspect, is that MSTS puts a limit the "MAX" numbers, which OR doesn't. I've seen MSTS .eng files with some ridiculous numbers, which pour out ridiculous amounts of smoke in OR, but look good in MSTS. I believe this is because they're way above the maximum (whatever that is) and so they're maxed out as opposed to actually working. I considered putting a max on the OR exhaust code, but decided not to in order to give modelers more flexibility. Robert Robert Murphy Open Rails Developer 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 Robert Murphy Open Rails Developer 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.