Quote Originally Posted by More Power
Let's not get testy... I just asked a simple (in retrospect maybe not all that simple...) question that I needed more info on....

I'm surprised someone didn't ask why I posted this in the "6.5L Turbo Diesel Forum".

I'm in the process of gathering more information... I received a couple of really cool photos (which I'll share soon), and I asked a few folks what they all meant. Aside from a factory girdle, billet cranks came up in the conversation (I had heard last year they would be forged - more later).... I still need to talk to a few who really have the scoop on what I saw...

Jim

PS... Did I mention an electric fan clutch?
I apologize for getting "testy"...

I've explained the differences and provided justification for the technical content of my comments. You choose who to believe.

It seems to be a safe assumption that GEP is developing some new stuff. Their choice of "billet" over forged is nothing more than an economic choice. They will probably be able to engineer a machined from solid piece that will out perform the cast pieces presently used. However, their decision mirrors that of GM in the first place when the decision was made to use cast cranks in these engines.

As for the electric fan clutch... I saw such a device on pre-production prototype gas pusher motorhome chassis using Chevy 8.1 liter engines last year. I thought then that this could easily be adapted to the 6.5. At that time, I was not allowed to speak about what they were doing for competitive reasons.

As for sections with carburize etc., look them up in your engineering texts. This stuff is usually covered in second year engineering classes. I've posted photomicrographs of nitrided surfaces in the past. That generated more questions than it answered.

Briefly, carburizing, nitriding, induction hardening, "tuftriding", nitrocarburizing, etc. are processes that increase the surface hardness of a part while leaving the core in a softer state. This increases the fatigue resistance of cyclically loaded parts because of the residual compressive stresses produced near the surface. This is due to the change of phase of the material from the hardening process (reference your metallurgical texts for a discussion of the phase diagrams for various materials) that increases the volume of the material at the surface.

These hardening processes all have advantages and disadvantages that must be carefully considered. Esentially, materials that are used with nitriding are different from materials that are used with carburizing and are different from materials used with induction hardening. The processes are not interchangeable.

The "best" process, from a strength standpoint, is carburizing. However, there are many other considerations that dictate the use of the other processes in many situations. These other considerations make the other processes "better" in those circumstances.

This discussion, though, is off the topic of this thread.

4130 steel was mentioned in a previous post. Can anyone explain what the numbers in the designation mean? How about 9310 steel or 1010 steel or 8620 steel or 5150 steel? What are each of these materials commonly used for? Which heat treat process or processes should be used with each?