Forged or Cast crank and rods which is better

[thexav]

Can someone explain the difference between forged and cast cranks and rods in an engine.

What would be better and stronger and why?

What is forging and casting? Are there other options which would be worth considering?

 

[old-git]

Cut and pasted from elsewhere:

Casting is the process where metal is heated until molten. While in the molten or liquid state it is poured into a mold or vessel to create a desired shape.

Forging is the application of thermal and mechanical energy to steel billets or ingots to cause the material to change shape while in a solid state.

The casting process is useful for a wide range of wearparts and components that are too large, complicated, intricate or otherwise unsuitable for the forging process.

The advantages of casting include:

• No real upper size limit in casting weight
• Large range of alloy choices
• As forgings remain solid, custom alloys are far more difficult to get into production whereas with casting, alloys including Chrome, Nickel and Moly can be added at the molten stage.
• Tooling is often less expensive than forge dies
• Smaller production “runs” required
• Complicated/complex parts are no problem

Forging offers uniformity of composition and structure. Forging results in metallurgical recrystalisation and grain
refinement as a result of the thermal cycle and deformation process. This strengthens the resulting steel product particularly in terms of impact and shear strength.

Forged steel is generally stronger and more reliable than castings and plate steel due to the fact that the grain flows of the steel are altered, conforming to the shape of the part.

The advantages of forging include:

• Generally tougher than alternatives
• Will handle impact better than castings
• The nature of forging excludes the occurence of porosity, shrinkage, cavities and cold pour issues.
• The tight grain structure of forgings making it mechanically strong. There is less need for expensive alloys to attain high strength components.

 

[lostviking]

Forged will be stronger than cast. It will also be a bit lighter. It will also cost a lot more. It cast is strong enough for your use, that's all you need.

I have drag raced big block Mopars using a cast crank, in the right application at the right power levels.

If you are in there anyway, and are planning on more power increases it might be a good idea to get the bottom end strong enough for the eventual power levels now. It would save you from redoing the bottom end when you did need it.

Tim

 

[HDi fun]

Anyone know about fracture split bottom end bearing shells?

 

[TCJBOLDIE]

Will a forged crank be stronger than a billet crank

 

[SLEEPER]

nice point ( can of worms opened for sure )

Depends on who makes the billet crank .
Potentially if all were made to the highest stadard possible I beleive they should be stronger