Piston and Rod options

parttimepuller

parttimepuller

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May 4, 2007
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Going to start pieces the motor back together... Old motor had 06 CR Piston and rods in it..... I have been hearing people say DONT run CR rods.... Believe I found some 235 SO rods and was going to use my pistions... Where are some good reliable shop that can balance and cut my pistons? Going to be going with one of Bill's cams...
 
The CR guys are breaking the CR rods...last I knew Brandon's little S10 has CR rods in it, and they're holding up fine.

It think it's the low RPM they are stuck with making BIG power that is breaking rods...spin them up twice the RPM in a 12v, and they seem to last longer.

Now, that being said, I swear there were Powdered metal CR rods and Forged CR rods, but that info was from quite a ways back, and I've never been able to confirm it.

Chris
 
CR rod's work better at a higher RPM CR rods are a Cracked Cap design and made different which makes it weaker.

Forged rods seem to work better in a CR and CR rods seem to work well in a 12V

I am putting a set of forged rods in my build up .
 
SPEAKSUP said:
CR rod's work better at a higher RPM CR rods are a Cracked Cap design and made different which makes it weaker.

Forged rods seem to work better in a CR and CR rods seem to work well in a 12V

I am putting a set of forged rods in my build up .
Click to expand...

Just to clarify, the cracked cap doesn't make them weaker, but the different material/process does.

Don't think you meant it that way, but was clarifying;)


We use fracture split, forged rods in our SisuDiesel engines...the factory sponsored pullers spin those up to about 7000RPM, at 2500hp, single charger...factory rods, crank, and cut pistons.

Chris
 
SPEAKSUP said:
CR rod's work better at a higher RPM CR rods are a Cracked Cap design and made different which makes it weaker.

Forged rods seem to work better in a CR and CR rods seem to work well in a 12V

I am putting a set of forged rods in my build up .
Click to expand...

:bang
 
Cracked rods refers to connecting rods made using powder metallurgy, The cap is then separated from the rod by a fracturing process, which results in an uneven mating surface due to the grain of the powdered metal.

Now as said it's the torque at a lower RPM that is killing them. Which is where the older forged rod's seem to be taking care of that problem.

There are guy's spinning more RPM'S and ETC. That seem's to work just fine with them.

I am not pulling this truck I am building it completely different for Torque at Low RPM I was not taking the Chance so I got some Connecting Rod's That I am going to replace the Cracked ones with.
 
parttimepuller said:
My motor will be a higher RPM motor 5K+
Click to expand...

Then you should have no problem. Just stating my opinions gathered from many other threads and talking to other people Bean's ETC about the same problems.

With him going through two engines 5.9 and 6.7 I would shot peen them though.

Just for good measure. Triton and other's seem to be running fine with just Shot peened rod's.
 
I got some 24v rods if you need. might need some help with the truck in a week or two :) just dont seem to have enough time.
 
SPEAKSUP said:
Cracked rods refers to connecting rods made using powder metallurgy, The cap is then separated from the rod by a fracturing process, which results in an uneven mating surface due to the grain of the powdered metal.

Now as said it's the torque at a lower RPM that is killing them. Which is where the older forged rod's seem to be taking care of that problem.

There are guy's spinning more RPM'S and ETC. That seem's to work just fine with them.

I am not pulling this truck I am building it completely different for Torque at Low RPM I was not taking the Chance so I got some Connecting Rod's That I am going to replace the Cracked ones with.
Click to expand...


I know what a fracture split rods is, and I know what powdered metal and forged rods look like, and can tell the difference. The rods we use in our SISU engines are forged, and fracture split...I have even seen them being made at the factory in Finland.

Now the Cummins CR rods, all I have seen were powdered metal...

Chris
 
I have run both 12V England rods and SO VP44 rods, cryo'd, without issue at 5K+ RPM and ~1000hp give or take.
 
The Cummins CR rods are not a powdered metal. The steel used is a forged C70 alloy. A crackable steel developed specifically to alloy the cap to be cracked. Cracked caps add strength VS a similar designed machined cap.

The C70 starts as a blank billet of material and is hot, hammer forged like any other forged rod. Powdered rods are never billets, by comparison. They are pressed or "compacted" from a powder.

After forging the C70 rod is pierced, trimmed, shot peened, and a small groove is machined to facilitate the "cracking" of the cap. The CR rod is stronger than any other factory rod made in most respects. All factory rods have a power limit. Go to an aftermarket rod for the highest power applications.
 
Thanks for the advise guys.... Already have the CR pistons so I might as well have them sent off and cut and cryo'd
 
So what rods would be ideal for a high rpm engine. I have heard that the England 24valve rods are the best option. Is this true?
 
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