Stock Crank Limits? Compounds?? September 08, 2021 01:53AM
Does anyone have experience with compound turbos on a stock BBJD crank?
What is the limit of a stock crank if it's girdled and billet rods? 3,000 ftlbs?

I know a guy did compounds a while back on a 6030 with a S475 and S463, but it wasn't a dedicated puller at 1500+ hp.
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Re: Stock Crank Limits? Compounds?? September 14, 2021 11:52PM
No one has any insight on compound turbos??
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Re: Stock Crank Limits? Compounds?? September 15, 2021 01:40AM
i dont think it matters if its compound if the boost pressure is the same. the crank doesnt know 100 PSI threw 3 small turbo or threw 1 big pro stock turbo. what hp are you trying to make with the stock crank?
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Re: Stock Crank Limits? Compounds?? September 15, 2021 03:41AM
I disagree. I don't know the answer to the OP's question, but WHERE compounds can make that 100 psi vs a large single is very different. Low rpm torque numbers will be higher on a compound and that's where stuff starts breaking.

CP
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Re: Stock Crank Limits? Compounds?? September 15, 2021 06:04AM
CP - Exactly the point of my question. The compounds are going to make more TQ lower in the power band than a large single is going to. The ~tolerance of error~ provided by a large single on a diesel is helpful in keeping the hard parts together... it's just smokier, can snuff sooner, and not always in the efficiency zone of the map.

If no one has the experience of compounds on a stock crank, then perhaps those that have broken the stock crank can share what kind of power levels it happened at (with a large single).

Thanks
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Re: Stock Crank Limits? Compounds?? September 15, 2021 06:05AM
This is an uneducated answer... not even helpful
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Re: Stock Crank Limits? Compounds?? September 15, 2021 06:06AM
Intended to "cranks doesnt know" ...
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Re: Stock Crank Limits? Compounds?? September 15, 2021 06:58AM
We run stock cranks that have been fully counter weighted. We run 3 turbos and see 200 psi of boost. The block is girdled. Low rpms and high boost seems to be what hurts the crank. We also have spun bearings with very high rpms also.
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Re: Stock Crank Limits? Compounds?? September 15, 2021 07:46AM
Scrap yards love compounds. I can attest to that, especially with stock cranks! Been there, after 2 bbjd stock crank failures we gave up on the idea.we were running a s366 and a s400. We now run a single s400 series much more durable. By the way if you open it up above 3k, bad things happen to! We are 720 ci by the way just fyi
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Re: Stock Crank Limits? Compounds?? September 15, 2021 09:38AM
Scrapper 5 - do you have a contact number? It won't let me message you. Thanks
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