What type of metal is the factory 3.8 crank made of??

[smokinttype]

What type of metal is the factory 3.8 turbo crank made of?? is it steel, cast iron or what?

 

[Nick Micale]

Cast iron.

 

[Scott231]

Originally posted by smokinttype
What type of metal is the factory 3.8 turbo crank made of?? is it steel, cast iron or what?

That would be the elusive "Not strong enough metal"

 

[GNVAIR]

Was paper mache a choice?

 

[smokinttype]

whats the difference in the metal in the 84-85 cranks and the metal in the 86-87 cranks??? obviously the 86-87 is capable of holding alot more power.....correct??

 

[KendallF]

Originally posted by smokinttype
whats the difference in the metal in the 84-85 cranks and the metal in the 86-87 cranks??? obviously the 86-87 is capable of holding alot more power.....correct??

Incorrect..the turbo rolled fillet crank was unchanged from at least 83 thru 87. The NA cranks are essentially the same casting but lack the rolled fillets on the rod journals. See www.gnttype.org for pictures and some good tech info for cranks and many other components.

 

[SPEEDSTAR]

The rolled fillet cranks are made of nodular cast iron , it is a lot stronger than a non rolled fillet standerd cast iron crank that came in NA 3.8 engines . The rolled fillet cranks came in the 4.1 and all turbo 3.8"s since 79.

Jeff

 

[smokinttype]

thanks

 

[KendallF]

Originally posted by SPEEDSTAR
The rolled fillet cranks are made of nodular cast iron , it is a lot stronger than a non rolled fillet standerd cast iron crank that came in NA 3.8 engines . The rolled fillet cranks came in the 4.1 and all turbo 3.8"s since 79.

Jeff

The only difference in the turbo cranks vs. the NA cranks is the hydraulically rolled fillet. They are the same nodular iron casting. Quoting from the Power Source book, "Production crankshafts are all nodular cast iron.."

The 4.1 is a good source for these cranks; between myself and a buddy of mine, we've gotten at least 5 of them that way.

 

[Dr. Freeze]

My company (Deep Freeze Cryogenics) has cryoed quite a few 3.8 cranks for local Turbo Regal guys lately... The problem with nodular iron crankshafts is two-fold: most of them are not tempered (heat treated) but are instead "work hardened" by the machining process... That's not really a problem with hardness per se but anytime you cast, forge, machine, or weld any material you are introducing stresses... These stresses cause stress risers and stress fracturing (the number one cause of failure in nodular iron cranks). Heat treatment relieves some of these residual stresses but since they aren't heat treated in the conventional manner therefore all of the stresses remain... The cryo process relieves 100% of these stresses as well as providing a "through hardening" of the journals to alleviate the adhesive wear associated with the journals/bearings... Obviously they still aren't as strong as a 4340 piece but the increase in durability is substantially increased and I would equate them roughly with a 5140 forged unit...
-Jeb