Posted By: cudaman1969
5.7 stock crank question - 12/03/15 12:43 AM
Ok, I hear the cranks are weak but who has broken a 5.7 crank and how much power or rpm did it take?
5.7 stock crank question
Posted By: kilo1
Re: 5.7 stock crank question - 12/03/15 02:01 AM
Not many broken cranks that I have seen , on engines with about 600 HP with no issues.
Posted By: dizuster
Re: 5.7 stock crank question - 12/03/15 03:27 AM
I have two stock core motors, one has a broken crank. But I haven't taken it apart to diagnose. But it's just stock... Not 600hp
Posted By: HotRodDave
Re: 5.7 stock crank question - 12/03/15 03:31 AM
I have seen a lot of broken rods in 5.7s but never a broken crank.
Posted By: rumblebee4232
Re: 5.7 stock crank question - 12/03/15 04:16 AM
Never seen a broken crank just rods.. one I bought to use as a stroker had a rod journal that was wore down 1/4 inch(below the surface all the way around) that was still running when they pulled it because it was making noise..
Posted By: Uhcoog1
Re: 5.7 stock crank question - 12/03/15 03:41 PM
Lots of used forged takeout 6.1 cranks out there for cheap ($150). Not worth running the stock 5.7 crank if building the motor IMO
Posted By: cudaman1969
Re: 5.7 stock crank question - 12/03/15 06:16 PM
Originally Posted By Uhcoog1
Lots of used forged takeout 6.1 cranks out there for cheap ($150). Not worth running the stock 5.7 crank if building the motor IMO
Been looking, I haven't found one that cheap, let me know if you know of one somewhere. Best I found was $450
Posted By: HotRodDave
Re: 5.7 stock crank question - 12/03/15 07:04 PM
I heAr the 6.1 crank drops in but how could the balance be right with bigger bores resulting in bigger pistons and rings? Or is it just close enough it don't make a difference?
Posted By: 72Swinger
Re: 5.7 stock crank question - 12/04/15 01:43 AM
I would balance with the 5.7 bore pistons used and whatever rods of choice. Also would use a 6.1,balancer at a bare minimum.
Posted By: 72Swinger
Re: 5.7 stock crank question - 12/04/15 01:48 AM
Also wanted to add that the 6.1 crank I pulled out of my core engine is NICE. All counterweights fully machined and dressed, no rough flashing anywhere. The Manley I replaced it with only had drilled rod journals as an advantage.
Posted By: mshred
Re: 5.7 stock crank question - 12/04/15 05:43 AM
Isn't there the higher rpm oiling issue though with the stock cranks?
Posted By: Uhcoog1
Re: 5.7 stock crank question - 12/04/15 11:17 PM
Originally Posted By cudaman1969
Originally Posted By Uhcoog1
Lots of used forged takeout 6.1 cranks out there for cheap ($150). Not worth running the stock 5.7 crank if building the motor IMO
Been looking, I haven't found one that cheap, let me know if you know of one somewhere. Best I found was $450
Try LXforums. Or I have one out of a spun rod bearing motor, just no box for it ATM.
Originally Posted By mshred
Isn't there the higher rpm oiling issue though with the stock cranks?
They are cross drilled. The drag pak guys turn em to 8200-8500 without issue with a 9 qt pan + 3 qt accusump. You will run a 6 qt swap pan dry around 7500 (ask Joe- he knows first-hand).
Posted By: CHAPPER
Re: 5.7 stock crank question - 12/05/15 03:09 AM
Originally Posted By Uhcoog1
Originally Posted By cudaman1969
Originally Posted By Uhcoog1
Lots of used forged takeout 6.1 cranks out there for cheap ($150). Not worth running the stock 5.7 crank if building the motor IMO
Been looking, I haven't found one that cheap, let me know if you know of one somewhere. Best I found was $450
Try LXforums. Or I have one out of a spun rod bearing motor, just no box for it ATM.
Originally Posted By mshred
Isn't there the higher rpm oiling issue though with the stock cranks?
They are cross drilled. The drag pak guys turn em to 8200-8500 without issue with a 9 qt pan + 3 qt accusump. You will run a 6 qt swap pan dry around 7500 (ask Joe- he knows first-hand).
I had a 10qt pan with belt drive Barnes oil system turning about 7200-7300 RPM and the stock crank......#3 rod quit oiling...DEVASTATING results. Molnar crank and no problems at 7800-8000 RPM. This has been hashed out for quite awhile. I, and many others, have concluded that there is a problem with the stock crank oiling. JMO...$.02...etc. Try one yourself and report back later.??
Posted By: hudsonhornet7x
Re: 5.7 stock crank question - 12/05/15 03:36 AM
Would this be ALL stock cranks, 6.1 and 6.4 included?
Posted By: 72Swinger
Re: 5.7 stock crank question - 12/05/15 03:37 AM
I think the 6.1's have better prep than 5.7's.
Posted By: cudaman1969
Re: 5.7 stock crank question - 12/05/15 07:58 PM
Originally Posted By CHAPPER
Originally Posted By Uhcoog1
Originally Posted By cudaman1969
Originally Posted By Uhcoog1
Lots of used forged takeout 6.1 cranks out there for cheap ($150). Not worth running the stock 5.7 crank if building the motor IMO
Been looking, I haven't found one that cheap, let me know if you know of one somewhere. Best I found was $450
Try LXforums. Or I have one out of a spun rod bearing motor, just no box for it ATM.
Originally Posted By mshred
Isn't there the higher rpm oiling issue though with the stock cranks?
They are cross drilled. The drag pak guys turn em to 8200-8500 without issue with a 9 qt pan + 3 qt accusump. You will run a 6 qt swap pan dry around 7500 (ask Joe- he knows first-hand).
I had a 10qt pan with belt drive Barnes oil system turning about 7200-7300 RPM and the stock crank......#3 rod quit oiling...DEVASTATING results. Molnar crank and no problems at 7800-8000 RPM. This has been hashed out for quite awhile. I, and many others, have concluded that there is a problem with the stock crank oiling. JMO...$.02...etc. Try one yourself and report back later.??
Are the 6.1-6.4 cranks drilled the same as 5.7? Are the steel factory cranks junk too?
Posted By: MattW
Re: 5.7 stock crank question - 12/05/15 10:04 PM
No they 6.1 6.4 and I'm thinking 6.2 are not drill all the way through the mains.
I posted picture of 6.1 and 5.7 crank on here.
I posted picture of 6.1 and 5.7 crank on here.
Posted By: 72Swinger
Re: 5.7 stock crank question - 12/05/15 10:49 PM
The 6.1 crank in my above pics was a high mileage, broken valve spring core engine. Only imperfection was #3 main had a light scratch that would easily polish out. You can see it in the pics. It ate something as I think #3 is what feeds the heads IIRC.