So, I went over to Chris' to help he and Pete complete some electrical work in his paint booth room, as well as to do some scenery on the modules he's got. It was a lot of fun, particularly since I've never done any real scenery work before.
While I was there, we were talking about locomotive weight and pulling power. In earlier conversations, Dick seems to believe that the weight of the locomotive is more important than the specific motor. Chris agreed (within reason, since too much weight will pull too much amperage). But he suggested that it's also important how that weight is distributed on the drivers.
The locomotives in question were the Atlas RS-1 and the Custom Brass L-1. I was telling him how the Atlas can pull at least 7 more cars than the L-1 up the helix. But I haven't added any weight to the steamer yet, nor have I optimized wheelsets, etc on the freight cars. He suspected that the L-1 might be heavier than the RS-1, even though it can't pull as many cars.
Soooo, I checked. The RS-1 is 12 5/8 oz and the L-1 is 12 3/4 oz. So he's right, it's heavier (although just).
Next I hooked up the L-1 to the front of the train that the RS-1 had hauled up the helix, and simply started stacking some weights on top of the boiler. After about 5 more oz, it could pull the same train. There were a few places where it was slipping quite a bit (clearly the helix is not a perfect, steady grade). But it would pull it.
So the next real question, which won't be answered for a while since I need to put sound in the L-1, is where can I add the weight? Even a little more than what I had today would seem to be beneficial. But it's good to know that adding more weight will improve the performance. Maybe I'll take it over to Chris' again to try on his test track to see if the added weight greatly changes the amperage draw too.