I've been trying to find dimensions for the new LT6 flat plane crankshaft. I know the stroke is 3.15 inches and the engines bore spacing is 4.4 inches. I'm looking for journal diameter, width and spacing. The end goal is to put a flat plane crankshaft in an LS block. Nobody involved in this undertaking is under any illusions about this being simple, easy or the best way to reach a given power goal. Our options at this point are a custom crankshaft from one of the usual vendors, machine one from a big block of 4330M in one of our shops or maybe get lucky and be able to use a LT6 crankshaft with some modifications. Any information you have would be greatly appreciated.

 

What do you see as advantages in the flat crank?

 

It is completely different design.

Found on corvette forum

For what I bet would be less money than GM would sell you an LT6 crank you can just buy one from Bryant Racing or other custom crank manufacturers.

https://bryantracing.com/

 

Over a year ago I talked to Crower about exactly this. I even modeled one up in Solidworks (also did one for an LT4). They said budget for about $2500 for any custom LS or LT crank, flat or otherwise. Of course, you'll also need a custom cam grind. Comp Cams says around $900 or so, regardless of firing order. The rest is some tuning software tweaks, lightest possible rods you can find, and lots of self-locking fasteners, Loctite, etc., to hope it all stays together...