Stock Cummins Rod Breaking Point

gs1000 said:
Wouldn't torque be the main factor? We know that torque is what is measured and the HP is mathematically derived. A CR making 1000hp at 3000 rpm makes a lot more torque then a 12v making 1000 at 4500. To make 1000 hp at 3000 you would need 1750 lb/ft of torque. If the stock rod can survive that then could it survive at 1750 lb/ft at 4500 rpm making 1500 hp or 5500 rpm making 1800 hp? Is this how BBD was able to do it lower torque at high rpm?

I really like this discussion and would like to see the torque aspect involved.
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Winner winner chicken dinner
 
outlaw99 said:
up down all around.... hahahah im not picky...:pop: now forguy24... he will take a 0 and drink a few and put that 1 in front of 0 like no other...:stab:
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I've also been know to flip a 6 over so she apears as a 9.


Back to rods.
 
I ran stock 12v rods at 1100 hp for a season on my 4wd. But with a single charger, and no low rpm 1-2 shifts. If your running twins, you will need them well before that hp level. We ran twins on our 2wd with 12v rods in the beginning. We started bending them around 1100 hp on that setup. Aron ran the stock cr rods in his 6.7 at 900+hp. But again with a single charger. I think the cr rods are just as strong as 12/24v rods. Only difference is the cr's will break and the 12/24s will bend(most of the time).
 
My searching and conversations lead me to understood stock cr's are good to 900 daily driven. Mine were fine near 800 when the gasket popped.

Went with 12/24v polished, shot peened and of course balanced. Would be nice if i have enough injector for 1150-1200whp.

How much does the piston ring play into rod stability? z-gap vs oem.
 
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The old 12v's dont generally have the ability to burn lots of fuel at low revs without huge amounts of smoke. The newer common rail trucks have a finer spray and Im sure the bowl setup is more efficient too. And youve got the variable turbo too. Lots of advantage at low rpm and lots of potential for high loads making that torque.
Im kinda curious about this torque versus HP thing since Im setting my truck up with a low stall converter and eventually a super over turbo setup so it runs clean with more fuel off idle. See how it compares to a 'normal' build.
To make it more complex, I wonder whats going on in an auto trans when youre pushing high torque numbers at low RPM. potentially less fluid pressure on the clutches. more slip, more wear. more notches in the fingers of the clutch baskets.
Its easier and safer to make HP and torque up in the higher RPM for sure. and not just for the crank / rods. But sure is fun to drive when you can accelerate instantly.
 
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With each strength improvement that you guys have mentioned, have any present stress risers been removed? The higher we rev the easier we stretch the more fuel we inject the easier we compress and like has been mentioned, timing will effect either.

To make it more complex, I wonder whats going on in an auto trans when youre pushing high torque numbers at low RPM. potentially less fluid pressure on the clutches. more slip, more wear. more notches in the fingers of the clutch baskets.
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I wouldn't say more torque is reducing your friction between the disks and plates but the output has surpassed the capabilities possibly of the clutch pack and fluid design if enough pressure is still being fed to the clutch drums and drum bands.

Your idea of leaner cleaner burn idea, I am not sure if you have heard of Larry Widmer but he did some out of the box combustion design (it stirred the pot pretty good) in the early 80s for gassers that you may want to check and see whats involved. I know you are always on the hunt for swirl and its effects. Read some of Harry Ricardo's work on the rapid burn as well.
 
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