*** Disclaimer: I haven't tried hooking up these outputs -- this is just theory. ***
The first thing I thought of when I read your post was that Prop Cycle has a blower fan so I put "github MAME propcycl" into a search engine. (propcycl is the ROMname for Prop Cycle)
That led to the
namcos22.cpp driver source code.
Search through the driver's MAME source in your browser by using CTRL-F, "fan" (or other keyword), then find previous/find next to step through all nine instances where "fan" appears in the file.
- This process confirmed on lines 64, 974, 2587, and 2682 that Prop Cycle has a fan output.
- It also confirmed on lines 975 and 2655 that Aqua Jet also has a fan output.
If a game doesn't have an output, you still might be able to use a LUA script to read a speed-related value from the game's memory and turn that into a fan output.
- Alpine Racer would be an excellent candidate for this approach because your current speed is displayed in the lower right corner of the screen during gameplay. (7:25-9:04)
Scott