[Connolly]

I am about to begin build my new motor and will be chasing some decent hp figures. I was just wondering what everone's opinions are of the stock crank and how much they can handle. I am getting mine shotpeened/nitrided and was hoping that will be enough. A few people over here in Oz dont seem to think that they will be up to the task, but I havent read of any failing other than stroker cranks with boost. I tried a search but this topic does not seem to have been discussed.

 

[bumpin96monte!]

Most machine shops also can remove the casting ridges, this is supposed to help prevent stress fractures. Can't remember if thats considered grinding or polishing the crank, but its one of the two. These cranks can hold up to quite a bit though, since I've never seen an aftermarket crank, I'm assuming all high end motors are running "race prepped" factory cranks.

 

[dougsgtp]

im 99% sure that intense is running just a slightly worked stock crank in their car

 

[Connolly]

Slightly worked as in heat treatment/cryo?

 

[ravenvtsuper6]

What about knife edging the counter weights. My engine builder/tuner wants to do this to my crank (L67) in a few months when we strip it down for cam and head work.

 

[spd98]

Get it micro polished. Gp's in general haven't had alot of problems with crank failures. Look at Chris Yates he just set the non Ic quater mile time with a stock bottom end.

 

[mcshocks]

What about knife edging the counter weights. My engine builder/tuner wants to do this to my crank (L67) in a few months when we strip it down for cam and head work.

No reason to we have a windage tray built into the gasket. I had my crank crosdrilled/chamfered/polished and it has worked well for the past 5,000 miles so far, spinning up to 6,600-6,700rpm almost everytime the car see's the road.

 

[OZ38]

So I take it from these answers nobody over there is doing a aftermarket steel crank for these engines ?

 

[spd98]

There are some places that owuld do custom ones but who wants to spend 2k on one when noone is breaking factory ones.

 

[bumpin96monte!]

Yeah, i think milzy got a quote for a custom crank for like $2500 IIRC, they're very expensive if you want a one-off from a company for a product like that.

 

[GR8racingfool]

I have only seen one stock L67 crank break:
http://www.clubgp.com/newforum/tm.asp?m=1706847&p=1&tmode=1&smode=1

I have seen rods a lot..and this one here was a result of a bearing falure:
http://www.clubgp.com/newforum/tm.asp?m=1705373&p=2&tmode=1&smode=1

I dont remember if these were upgraded L32 or not.

Our stock cranks are pretty stout as they are, I think when you get a shop grinding, and doing a lot of stressful additional work on them it would weaken them. I say in my opinion, not to change it. If your crank requires regrinding, just get you a new or a used low milage crank and use that one. Most the shops that can do that stuff, work on V8's 98% of the time. Be it all cranks work the same...but a lot of shops dont kow our Series II engines from the "Buick V6 - 231's".

Just my advice for those who are getting extensive crank work done.

All I did to mine for my engine build was I cleaned it once it was removed, took it to a shop 1 and had it polished, took it to shop 2 with a lot of needed parts and had it 50% balanced - Done.

~Farnsworth~