Keep up the good work Chadiman. I've been following your dyno build threads since you started them and am very impressed with your build. I used to work for a diesel engine manufacturer back in the eighties and the standard way of testing them was with water brakes. Basically the engine turned a turbine supported in trunnions and the torque was measured by an arm with a glorified spring balance (with counterweighting for different power outputs so as not to go overscale) Yes the water got hot and the valving had to be adjusted to allow for it but it made no difference to the torque being measured.
You will have losses from the chain drive so you won't get the crankshaft figures quoted from the manufacturers. But surprise surprise a chainsaw won't cut wood without a bar and chain attached to it so the readings you are getting will be much more real world. Cars are tested on rolling roads and the figures aren't what the factories quote at the crank.
You could correct for temperature, humidity and barometric pressure but comparisons on a given day compared to a base saw like you have been doing are just fine. Even after correction I know from experience that the SAE and ISO standards allow a lot of wriggle room for the statisticians to get the answers that the marketing department were after.
I also admire your patience in answering all the naysayers who have been on your back but trust me you are on the right lines
