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Re: 3.58" crank
[Re: 70Cuda383]
#1141618
01/13/12 03:48 PM
01/13/12 03:48 PM
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Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
patrick
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
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Quote:
Quote:
???
A forged thing is heavier then a cast thing.
when made identically, yes.
but often times, Forged pistons are lighter than their cast counter-parts, because the stronger forging allows for less material at the same or greater overall strength.
Especially when you start comparing aftermarket forged pistons to heavy stock cast ones.
NO the density of steel is the same, whether it's cast or forged, 7820 kg/cubic meter. if 2 cranks are dimensionally identical (both displace the same volume), their mass will be the same even if one is CAST STEEL and the other is forged steel.
IF a crank is dimensionally identical, but the cast one is lighter, then it is not CAST STEEL. then it is most likely DUCTILE CAST IRON, also known as NODULAR IRON. it's density is about 10% less than steel, due to the much higher carbon content (which, in ductile iron is in the form of little spherical nodules dispersed though the continuous iron phase)...IIRC it's manganese as an alloying element that causes the carbon to form nodules vs. flakes like in traditional (grey) cast iron, but it's been 16 years since I had any metallurgy classes.
1976 Spinnaker White Plymouth Duster, /6 A833OD
1986 Silver/Twilight Blue Chrysler 5th Ave HotRod **SOLD!***
2011 Toxic Orange Dodge Charger R/T
2017 Grand Cherokee Overland
2014 Jeep Cherokee Latitude (holy crap, my daughter is driving)
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Re: 3.58" crank
[Re: patrick]
#1141619
01/13/12 04:24 PM
01/13/12 04:24 PM
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Joined: Jan 2003
Posts: 2,933
Finalnd, Perkele
jyrki
master
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master
Joined: Jan 2003
Posts: 2,933
Finalnd, Perkele
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It's just as easy to compress metal as it is to compress fluid. No can do, so, unless it's a porous casting,the weight of a cast and forged object with the same displacement should be the same. I'm as far of a scientist as you can get, but still I have a theory about cast and forged cranks differencies. Has anyone really weighed them? Because, my first tehory is that since the cast crank is weaker, they have to make the crankpin size heavier duty than in a forged crank, and since the counterweight sizes are the same, the crank needs external balancing. So, it's actually heavier, not lighter, than the forged crank (yes, haven't weighed for example a 383 forged and cast crank). The second theory is that because of the porousity, the counterweights of the cast crank are lighter... 
Plynouth VIP '67 TT IC EFI
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Re: 3.58" crank
[Re: jyrki]
#1141623
01/13/12 08:39 PM
01/13/12 08:39 PM
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Joined: Oct 2003
Posts: 21,345
Marysville, O-H-I-O
70Cuda383
Too Many Posts
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Too Many Posts
Joined: Oct 2003
Posts: 21,345
Marysville, O-H-I-O
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Quote:
It's just as easy to compress metal as it is to compress fluid. No can do, so, unless it's a porous casting,the weight of a cast and forged object with the same displacement should be the same. I'm as far of a scientist as you can get, but still I have a theory about cast and forged cranks differencies. Has anyone really weighed them? Because, my first tehory is that since the cast crank is weaker, they have to make the crankpin size heavier duty than in a forged crank, and since the counterweight sizes are the same, the crank needs external balancing. So, it's actually heavier, not lighter, than the forged crank (yes, haven't weighed for example a 383 forged and cast crank). The second theory is that because of the porousity, the counterweights of the cast crank are lighter...
Ok, I always thought forged was a little more dense than cast.
if they are the same density, and weigh the same...then why is a stock forged 440 crank heavy enough to internally balance, when a stock cast 440 crank is not heavy enough and needs external balance?
are they not cast steel?
**Photobucket sucks**
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Re: 3.58" crank
[Re: 70Cuda383]
#1141626
01/16/12 11:58 AM
01/16/12 11:58 AM
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Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
patrick
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
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Quote:
Quote:
It's just as easy to compress metal as it is to compress fluid. No can do, so, unless it's a porous casting,the weight of a cast and forged object with the same displacement should be the same. I'm as far of a scientist as you can get, but still I have a theory about cast and forged cranks differencies. Has anyone really weighed them? Because, my first tehory is that since the cast crank is weaker, they have to make the crankpin size heavier duty than in a forged crank, and since the counterweight sizes are the same, the crank needs external balancing. So, it's actually heavier, not lighter, than the forged crank (yes, haven't weighed for example a 383 forged and cast crank). The second theory is that because of the porousity, the counterweights of the cast crank are lighter...
Ok, I always thought forged was a little more dense than cast.
if they are the same density, and weigh the same...then why is a stock forged 440 crank heavy enough to internally balance, when a stock cast 440 crank is not heavy enough and needs external balance?
are they not cast steel?
either they are ductile iron (9% lighter) or they are different geometry (less material)
I'm pretty sure they're actually ductile iron (nodular iron), not cast steel though.
1976 Spinnaker White Plymouth Duster, /6 A833OD
1986 Silver/Twilight Blue Chrysler 5th Ave HotRod **SOLD!***
2011 Toxic Orange Dodge Charger R/T
2017 Grand Cherokee Overland
2014 Jeep Cherokee Latitude (holy crap, my daughter is driving)
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Re: 3.58" crank
[Re: RUNCHARGER]
#1141629
01/17/12 11:40 PM
01/17/12 11:40 PM
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Joined: Oct 2008
Posts: 1,176
East Coast
A/MP
super stock
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super stock
Joined: Oct 2008
Posts: 1,176
East Coast
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This is the real deal with cast factory cranks. A Chrysler factory crank LA motor will take 600HP in a light weight car 2800lbs. What is different between cast and forged(othet than metalugy) is the stress cyclces that the metal can endure. A 360 cast crank with 70,000+ miles whether light or hard use has reached a point wear the metal memory starts getting alzheimers. When the metal structure starts to move with the stress of racing it forgets its original place and starts moving away from its as cast structure. Once that happens the greater the chances of fracture of the metal structure and eventual failure. All forged china cranks whether scat,eagle,ohio,callies come from the same factory. When the china economy becomes stressed, the chineses look for a cheaper way out. This means a cheaper(quality) product.Products that were manufactued 2010,2011,? many fit this proverb. A real Callies crank is $1500.00+. Can it fail? Sure but the chances are slim. Look on ebay for a race W7 or W9 motor. Many of them are only test laps,and they with run low 9's as is. With cam and carb change high 8's. Someone else did all the engineering and at 15K not a bad deal, respectively.
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