2 different dynos,2 very different numbers.why?

When my engine dynoed it cost $450 for all day and the motor oil. Money well spent IMO and if I ever build anything else with some steam I'll do it again.

If it's an engine the owner built "torture chamber" is the right name for the cell! After priming and installing the distributor my engine fired right up, we set the timing and warmed it up. Then shut it off and checked the lash. The next time we fired it up and let it run for a few seconds, the operator looked at me and asked if I was ready, WFO and pulled to 7200. I'm not going to lie it made me a lot nervous seeing and hearing it, I'd never done that to a brand new engine.

My engine had an oiling issue on the passengers side rocker arms that I would've never heard if it had been started in the car and driven. On the dyno it could be heard and we shut it down to investigate, found the issue and fixed it and went on with the secession.

As has been mentioned it's a tool, some use it for tuning and some use it to make money off unsuspecting customers.