Something to be aware of with Scat crankshafts

sandlapper

Veteran Member
Oct 9, 2020
1,629
SE CSA
perhaps PRC has controlling stake in any consequential North American (crank) foundry ? Maybe only heavy duty/commercial/stationary/off-highway ? Maybe all ?
IIRC, a few years back I read in an industry trade mag, how that trend was becoming a strategic worry --- if not --- it certainly should be.
 

1980RS

Veteran Member
Jun 17, 2006
6,550
MN
Let me digest this. Cast crank is stronger than forged?
Nope not stronger but has more flex which sometimes can be a good thing my machinist said. The one thing IMO that kills cranks and other rotating parts is RPM and lots of cyl pressure. If you run an engine and shift at 5K it will live forever.
 

G72Zed

Veteran Member
Sep 8, 2015
4,228
Canada
Let me digest this. Cast crank is stronger than forged?

I agree with 1980RS in his #8 post. It's downright amazing what an OEM cast crank can take in a well tuned engine. Street and drag, they can last a long time.

Now, in an offshore boat or heavy loaded chassis on a DIRT track, not very long in those cases.

I ran 11.0's at almost 120mph back in the early 90's with my '71 full weight Camaro with a stock OEM cast iron crank in a 1968 327 2 bolt main block. Hit with 30 bottles on NOS over a few seasons, all with only a 150 shot, it had signs of cap walk and radial lines on the crank, but never broke, still have that crank.

And because I'm a gear head and like engine parts, I went with a Callies 4340 crank, billet splayed caps. Then removed the NOS, and I did not sleep any better LOL.

FWIW, Like in nature, it's not the stiffest tree's that survive, they break, it's the ones that bend that last.
 

procharged81

Veteran Member
Nov 16, 2011
139
NE PA
Almost every crankshaft you would buy is from China. There are very few aftermarket cranks that are not.
You are spot on my man! Everyone looks at these “American” companies and buys their products thinking they are American made. Truth be told, they are forged in Wuhan and “finished” here.
 

redandgearhead

New Member
Jan 4, 2008
12
DFW, TX
4340 steel is some really tough stuff, if heat treated correctly. It also is hardened down deep into the part as opposed to 4130 which tends to have a very thin hard outer layer. The hard 4130 outer layer can be brittle leading to crack formation which is why rods and cranks are not made from 4130. If the 4340 is not annealed and normalized, maybe there is a hard, brittle outer crust that is causing the cracking formation. If the Chinese cranks are not annealed after the initial heat treatment by hot oil bath quenching, then maybe this is causing the hard crust and the cracking.

A buddy worked for Cummins Diesel for awhile in the 90s into the 2000s. He said even back then there is only one or two manufactures for each major engine component. Maybe this is why I have heard there is a problem with flat tappet lifters eating cranks on break-in these days. Inconsistent heat treating of the lifters by the cheap Chinese manufactures.
 

G72Zed

Veteran Member
Sep 8, 2015
4,228
Canada
Got a Winberg in the shop, they from China too??? What about Crower, Bryant and Manley, all China as well.....

Perhaps China buying all the scrap steel all these years paid off for them if that's the case.

In the end, I do not see many/any broken cranks, pistons/rods , yep, many due to oil starvation, but no broken cranks, regardless of brand......and I even sleep better these days LOL.
 

Chevyforever

Veteran Member
Jan 4, 2011
1,512
Canada
Friends race a blown alcohol SBC dragster and 4-5 years ago discovered that "the chinese cranks, will not live " in such a severe use environment. Not sure what brand crank they are using now.
David Reher stated that a drag race engine sitting on the starting line on the chip for any longer than absolutely necessary is extremely detrimental to the crankshaft and main bearings.
 




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