What is a crank journal, and what does it do, and how would a larger one help when running lots of boost or got lots of hp.

 

A Crank journal is is a hole in which the journal of the crank sits in, there are also Main/Rod Bearings in this location. These holes keep the crankshaft aligned with the block.

Enlarging them will not give you any type of performance gain, I think you maybe getting confused by Bore Size, which is the size of the actual pistons. Larger bore size increases engine displacment (i.e 1.8l bored over to 84mm to a 2.0l) thus putting out more torque, and in some cases more hp.

Thats a simple explanation,

 

nicely put Jeff !

 

Thanks for the info, now i guess my question is what is the Journal of the crank?

 

crank journal = smooth silver shiney area where crank is bolted into the block. rod journal is where the piston rods are bolted to the crank. ??