NAV engine giving off too much smoke

[frliss]

Hi all,

I have asked a similar question in Open Rail discussion and never got a definitive answer. Since it is related to engine physics I'll try again here.

I've downloaded the T&P GP9 (File number 90021). It's a beautiful engine but I am getting way too much smoke. This is what it looks like in the latest version of ORNYMG.

Open Rails NewYear MG 2025-05-04 05-18-22.png

Also here is what it looks like in the latest testing version of OR.

Open Rails 2025-05-06 03-11-06.png
What can I do to reduce the amount of exhaust?

I've played with the values for Idle exhaust and Max exhaust with some success but I'm not happy with the results.

Can anyone tell me how to adjust the exhaust?

Fred

[charland]

Open the Eng file. Scroll down to DieselSmoke... and replace the values. Here are the values I've been using in Open Rails:

DieselSmokeEffectInitialMagnitude( 0.4 )
DieselSmokeEffectMaxMagnitude( 0.8 )
DieselSmokeEffectInitialSmokeRate( 0.4 )
DieselSmokeEffectMaxSmokeRate( 0.7 )

Paul :-)

[EldoradoRailroad]

What versions of OR/ORNYMG are you using?

Steve

[wmuzeke]

For those locomotives, the exhaust/smoke is coded in the engine physics include files. Look for these 4 files in the directory TRAINSET\NAVS_COMMON\SOO_GP9R_KIT\
NAVS_16-567C-0.inc
NAVS_16-567C-1.inc
NAVS_16-567C-2.inc
NAVS_16-567C-3.inc
Adjust these parameters within those files - IdleExhaust, MaxExhaust, ExhaustDynamics, and ExhaustDynamicsDown. Dialing down the ExhaustDynamics parameter should reduce the amount of smoke. This is also contingent on what diesel smoke texture is in your Global folder (dieselsmoke.ace).

[frliss]

Paul,

Open the Eng file. Scroll down to DieselSmoke... and replace the values.

That's the way I always did it in the past. However, that section in the NAVS .eng file doesn't exist.

wmuzeke,

Thats the way I'm doing it now. I guess I'll have to continue playing with these numbers till I get satisfactory results.

I have been told that adjusting the last number in the Exhaust1 and Exhaust2 in the eng file may help. I have my work cut out for me.

Fred

[frliss]

Steve,

What versions of OR/ORNYMG are you using?

I'm using the latest version of each.

Fred

[Erick_Cantu]

Open the Eng file. Scroll down to DieselSmoke... and replace the values. Here are the values I've been using in Open Rails:

DieselSmokeEffectInitialMagnitude( 0.4 )
DieselSmokeEffectMaxMagnitude( 0.8 )
DieselSmokeEffectInitialSmokeRate( 0.4 )
DieselSmokeEffectMaxSmokeRate( 0.7 )

Paul :-)

Those values would not change anything as these locomotives use an OR engine block. Editing the smoke values in the include files is not recommended as it would desynchronize the engine and smoke. The exhaust values used in the include files were calculated very carefully with purpose. A 2-stroke engine should emit a visible pulse every rotation due to the dynamics of cylinder scavenging and backflow in the pipes, even across multiple cylinders. The correct formula for calculating exhaust values in an OR engine block is RPM/40 for a 2-stroke engine and RPM/80 for a 4-stroke engine.

Adjusting the last number in the Exhaust1 and Exhaust2 sections changes the diameter of the exhaust opening and will result in changes in the exhaust velocity as well as exhaust streams that are either too narrow or too wide. The stream width was set to correspond to the spark arrestors used on the models.

Anyway, the exhaust in Fred's shots is too opaque because of the diesel exhaust texture being used. Try using one with a darker alpha channel.

EDIT: on second look, I'm pretty sure Fred's dieselsmoke.dds/dieselsmoke.ace texture is missing from the GLOBAL folder. The edges of his exhaust particles are completely square. I haven't actually gotten around to uploading the texture I use (which the models were designed to use), so, until I have the time to package it up properly, here it is: https://www.dropbox.com/scl/fi/7uvlde0vkuq7p30ipqnim/dieselsmoke.zip?rlkey=43q59w5ikw57le731kuz0f6th&dl =0

EDIT 2: Adjusted language for clarity.

[Big Boy 4014]

Here are the values I use for my diesels that smoke too much.

DieselSmokeEffectInitialMagnitude( 1 )
DieselSmokeEffectMaxMagnitude( 1.0 )
DieselSmokeEffectInitialSmokeRate( 2.0 )
DieselSmokeEffectMaxSmokeRate( 10 )

I hope this helps!

[charland]

dieselsmoke.zip

[charland]

OK, when I inserted the zip file the rest of the post disappeared.

I can't upload the engine file without zipping it too but here are the important bits:

DieselSmokeEffectInitialMagnitude( 1.0 )
DieselSmokeEffectMaxMagnitude( 2.4 )
DieselSmokeEffectInitialSmokeRate( 0.4 )
DieselSmokeEffectMaxSmokeRate( 1.4 )

The second and fourth values are higher then I use on EMD and GMD units just because they are ALCo/MLW.

The smoke ace is in my Global>textures folder.

This S-3 is in neutral in notch 4 to produce the smoke you see, I don't see anything that looks square so I'm not sure why Eric is.

Paul :-)

[charland]

I'm using ORNYMG 161.2 but the smoke has looked this way for years.

Paul :-)

[Erick_Cantu]

I don't see anything that looks square so I'm not sure why Eric is.

OR renders smoke as simple square polygons that always face the camera. These are called sprites, and they have a texture mapped to them. The alpha channel in this texture defines the "edges" of the smoke "puffs."

Dieselsmoke.dds/dieselsmoke.ace (OR uses either format) is a simple 16-frame texture map with an 8-bit gradient alpha applied and is the map used on the diesel smoke sprites. The 16 frames provide variety in the rendered sprites; and typically the alpha channel in most diesel smoke textures is fairly dark, making the individual particles fairly transparent, as this is much more accurate to real life than thick, dark particles. OR blends the base colour in the diesel engine block with the colour layer of the diesel smoke texture, then it blends the transparency value in the diesel engine block with the alpha value in the diesel smoke texture for the final transparency value rendered for each particle in-sim. When the diesel smoke texture is missing, OR simply doesn't blend any of its data in, resulting in the square sprite polygon with the base colour and transparency values from the diesel engine block being rendered in-sim.

Zoom in on Fred's second screenshot. Look at the top of the first plume of the lead unit's exhaust. Those aren't JPEG artifacts; those particles are squares rendered with the colour and transparency value specified in the ORTS diesel engine block. This is precisely what OR renders when dieselsmoke.dds/dieselsmoke.ace is missing from the global folder, and I think this is the root of Fred's problem.

[charland]

Here's a fine example of smoke. Canadian National 3227 an old C-424 along with two GP40-2(W)s. The train just started after stopping to change crews just about where the grey ACF hopper is, so they are hard on the throttle. The older C-424 is just puking out smoke, but in another few hundred feet you'll not see much, but the two GMs have no smoke showing, they've already had their little burst of smoke when the throttle was opened and that has dissipated.



June 1980, Brockville, ON.

Paul :-)

[pschlik]

Perhaps we need to include some default smoke textures in the Content folder of the OpenRails program, and use those if nothing can be found in the GLOBAL folder...

[geepster775]

Or just switch it to there permanently and ignore the Global folder for that going forward