This is "4340":
C% Carbon 0.38 – 0.43
Mn% Manganese 0.6 – 0.8 max
P% Phosphorus 0.035 max
S% Sulfur 0.040 max
Si% Silicon 0.15 – 0.3
Ni% Nickel 1.65 – 2.0
Cr% Chromium 0.7 – 0.9
Mo% Molybdenum 0.2 – 0.3
The balance is iron (Fe)...
Note there is an acceptable tolerance for all of the various elements. So, 4340 varies from one batch to the next. The best steel mills hold tighter tolerances. Beyond that, was the steel melted in open air, or was it Vacuum-Induction-Melted? Was it Electro-Slag-Remelted? Was is Vacuum-Arc-Remelted? How many times did the steel go though these processes, redundantly, to remove the oxidation and impurities?
When the rod was actually forged from the steel slug, what care was taken to keep it away from atmospheric oxygen while it was still hot? Was the forging machined and THEN heat treated, or was it heat treated prior to machining? What heat treatment process was used? What heat treat condition is the finished part in? What is its fatigue strength? Hardness?
None of these questions ask anything about the geometry of the finished parts themselves, and whether or not they are straight, with the big/small end bores parallel to each other and perfectly perpendicular to the long axis of the rod, or what the finished diameters or surface finish is, etc etc.
I suspect most of the lower-end forged H beam rods for the 2J come from the same steel mill in China. I suspect for the cheaper ones, like CX racing and Eagle, that raw forgings are machined and finished in China as well. The higher end ones like K1 and Manley are likely finished in USA, but this is purely speculation on my part. For sure, the higher end stuff like the Turbo-Tuff and Carrillo are made from start to finish in the US with premium steel that HAS undergone all the latest/greatest steel manufacturing techniques - and that is what you're paying for. You KNOW they're gonna be right.
So at the end of the day, you pays your money and you takes your chances. Personally, I'd buy K1 with ARP2000 bolts. Real Street endorses them and say they pretty much always use these rods for applications that make 175hp per rod, or less.
Last, I still see no reason why you can't ask your piston/rod/bottom end questions in a single thread. We don't need a new thread for each new question you have about them. If you bellyache about "haters" (that are thoroughly answering your questions in great detail) again, I suspect those same "haters" will stop replying.
Last edited by Hodgdon Extreme; 05-19-2019 at 01:26 PM.