You're right, that one hour estimate was intentionally optimistic.
I doubt if a Mark 5 has ever produced its rated 100 hp output. Sure, Harry used to brag on the steam car board about the land speed car engine "runnin' sweet" on the dyno. At one point he announced a testing program for this engine and said he would post the dyno results. People kept after him for the results, but he wouldn't release any real measurement data. When people started to doubt an engine was dyno tested, Harry posted a photograph of the engine on its stand as proof and started talking gibberish about publicly traded companies are not allowed to publish dyno measurements.
My favorite comeback was from someone who said "Stop telling us what it is GONNA do, tell us what it HAS done."
It's now three years later and there has been no mention of Mark 5 performance other than the engines for Combilift are finishing their 50 hour test runs.
That one-hour estimate was for the WHE engine, the low pressure, low temperature, low output and (super) low efficiency design. Surely they could have gotten one of those to produce some power and survive for an hour? After all, people have only been building working steam engines for 200+ years.
