These little CO2 motors look like lots of fun. Never seen one up close and will have to look around some. Any motor run times?

I'm doing this from the phone while we sort out the IT issues, so please bear with me I haven't started a CO2 build yet, but I'm fascinated by these little Expanding Gas Reciprocating Engines and I've collected a few, and the plans and/or kits I'm considering.
The Gasparin GMW73 TRV twin with the gas valve throttle and two tanks is a powerhouse- handbuilt by Stefan Gasparin hisself and one of not many with a gas valve. It will lift a pretty good sized AC and is tentatively slated for a Herr J3 cub.
The little Telco single isn't the piece of art the Gasparin is, but it runs good and might find a home in a Jetco peanut Dayton-Wright RB1,
The big Russian DP-O3 might as well be made of cast iron- It strong like Russian wife and needs to be in something light with a bunch of wing.
The tiny little Brown Campus A-23 is a sweetheart- 7.4g with the tank & prop and I'm thinking it might be fun in a Megow diner- I have printwood for a Taylor Cub and the plans are out there.
The last one is a G-Mot GM120T- The "factory-built" iteration of a Gasparin and it'll handle a fair sized model too and may be the one I do my first build for. I found loose printwood for a 3/4" scale Cleveland (yeah-another Cleveland) Aeronca C-3 and have the plans en route. I think those little jugs would be PERFECT hanging out of the cowling!
Meanwhile, Since we're just getting this CO2 thing rolling, I'm looking for a 1mm Brown charger and an 8x8 1/2 Gasparin prop.i look forward to getting back to building and felliwshipping with y'all!