rws

We used to run GM 1053 Cranks in the Orange Crush GP Hydroplane 10.0 to1 compression, 16 lbs of boost ,8200 RPM. Broke a lot of of rods, but I cant recall a Crankshaft failure.Callies is my brand of choice for aftermarket.

Rob

Elite Marine

Why are others so concerned about the 1053 vs the harder steels? Is longevisty an issue? Heat?

Whats the real issue? Most high end cranks are 4340 or 5140, why?

Apache22

My forged GM HO crank went south, Have a fly cut and balanced Eagle with NO problems in a 461 cu. in. 500HP application

excaleagle42

5140 is a higher quality of alloy than 1053. 4340 is superior to both. the general rule of thumb is 600 hp and above, go with forged. cast cranks are OK up to that point. i wouldn't worry about a GM forging until close to 800hp. i'm sure some have been used higher than that, that's just my preferance. not all cranks are made the same. some are hot twisted out of forged metal. others are cut out of a solid hunk of metal. they are billet cranks. they are the highest quality and the highest $ due to the time it takes to grind away all that metal. billet cranks have the best molecular grain structure so cracks and crank failure are least likely. most forged cranks are nitrided, which is a bearing journal treatment that increases the hardness of the surface so impurities in the oil that get stuck between the bearing and the journal do the least damage to the crank journal. if a GM crank has to be cut, if i remember correctly, they should be re-nitrided because GM's nitriding doesn't penetrate as deep as some aftermarket crank manufacturers. re-nitriding is expensive. if your looking at cutting a GM crank and re -treating it it may be worth it to just buy a new one. Kryptonite is also a very high quality crank that i don't believe was mentioned.
there are some things that can cause severe stress on a crank. stroker motors with higher rod angle ratios, heavy pistons and rods are also a bad idea on a high RPM motor. high piston speed and vibration is a killer. and lastly, normal harmonic balancers don't control the harmonics throughout the entire RPM range as well as a fluidampr will. they are a very good investment in my opinion.

mcollinstn

A forging will have the grain structure aligned with the stress direction of the crank better than any other method of crankshaft production. Cast is worse, billet is better, and forged is best.

This would in essence mean that the best cranks would be forged. This is not the case, though, cause some of the exotic crankshaft materials are not easily forged.

A billet crank made of premium materials is usually stress relieved in a thermal furnace after rough machining to rough size. Then a particular heat-treatment procedure is performed to bring the crank to a desired temper. Once this is done, the billet crank is a superior piece.

But a forging is the best piece if it can be fashioned from the target material in that manner.

(you never see billet pistons...)