Back in the day ,,( early 70's to late 80's)I was building off shore boat motors ..I had a GO Power .D512 unit..all analog ..No computers ..just load down the load cells and read the Large torque gauge and tach ..do the math as the chart says and come out with a HP number..It didn't matter what the HP was exactly. altho it was very close...just if the tuning made more or less power... Geez..I'm getting old !!!