In a past life I did some engineering 101 courses, including testing of various steels and metals and their properties.
The rig that did tensile testing ultimate yield simply pulled a bolt apart, and recorded how many TONS of
force it took to do it. (or part thereof for small diam bolts)
I've probably got enough crankshaft bolts about I can have tested an original and a newey and a generic grade 8, so we will see how they compare.
Mild steel is about 40 tons per sq inch, and I believe that aircraft and ARP's best steels are nearer 120-140 tons/sq in (?) these days, although
you wouldn't meet that quality every day, and the grade 8 should be at least 60-70 tons ?
The modern specs are all in MPa, will have to get up to speed on those...