Hello Ls1 tech, while I have my motor out I thought about upgrading my crankshaft from my current Compstar to a Dragonslayer or Lunati Pro Series. The problem is I dont want to pull my pistons and rings out the hole so I was gonna leave them in place while I set the crank in. My question is if I know the bob weight of my current crankshaft can I have the new one balance to that number and install it without complications?

 

Why are you upgrading?

 

I may go for more HP down the road. I'm running a F1a and may upgrade to the F1a-94 and aim for 1100-1200rwhp. So the switch is mainly for reliability.

 

Gotcha. With ring seal being so critical in trying to achieve power, especially in an FI build, I think you’d be doing yourself a disservice if you didn’t pull the slugs out of the holes and do a de-glaze and re-ring.
I saw a guy do a crank swap once with the technique your talking about. Personally I’m super **** about balancing, because a well balanced engine will always make more power than a engine not balanced, due to harmonics. I’d want my guy to spin everything to at least check, even if bobweights were same. That’s just me.
And then there’s the bearing clearance issue that I’d want to go over, which would be super tough with the rods swinging in the block, and not on a bench. You’ll have to torque them to check your numbers. I don’t see any thing good about leaving the hardware in the cylinders.

 

I've thought about everything you mentioned above. My ring seal is soooooooo good that I didn't want to mess with it but I see you points. I had a plan on how to check clearances but if I change cranks I may just get it all rebalance. However, if my short-cut was acceptable to most I would of went that route.

 

I’d bet a Compstar will handle 1000 or more hp, it’s still 4340 alloy. Start a new build with all the upgrades you always wanted.

 

Don't have that kind of money to build a completely new short block. Gotta make due with what I have.