Can this be true?

[Robertp]

Don, where can i find the testing info on these rods at?

[Timbeaux]

Originally Posted by Robertp

NGM 04 HO 10's <----------

We post sheets and video anytime Wade farts at the track, but we lost this one

Sorry for the Derail, but since we are on a fact-finding mission about rods, we migt as well stick to facts

[JOHNBOY]

Originally Posted by Soup Nazi

The Cummins CR, cracked cap rod is not powdered metal like the DMAX.

Its a C70 microalloy, forged steel that is crackable. The cracked joint is the strongest of all the factory designs.

They both use an 11mm fastener. The cracked cap will hold itself together easier in the cap area VS the machined rod.

In 2002, all the rods were tested...the cracked cap rod was the strongest in the tests performed. I have cracked cap rods in my 12 valve engine. No failures yet.

All that being said, Reb respectfully disagrees with me. He has bustamacated up more parts than I might ever. Not all his failures have been with the 6.7 either. He called me 2 days before Christmas and told me about the crankshaft he broke in his 03 we tuned to 1290 HP plus. BTW, that same engine that busted the crank..all connecting rods ( not the cracked cap style ) lived through that and are usable again.

So lab testing is great and fine and I still trust it, but it is hard to discount Rebs success with the old school rods.

Well I apologize for saying the CR rods where PM. I thought they where. I do totally agree that the fractured cap is a superoir union over a machined cap. But the union does not appear to be the failure spot.

To back up what said about the real benifit of fracture caps over machined is cost. It is a better union but IMHO it was a cost move.

Quote below taken from http://www.corusautomotive.com/file_...CES_Proda5.pdf

"In fracture splitting, the big end cap is removed from the
body of the connecting rod first by notching (usually by
laser) and then by fracturing. The fracture splitting
process offers major savings in the through-cost of
connecting rod manufacture. A reduction of as much as
25% in plant investment costs and 35% in the
processing costs of machining lines are claimed."

The data I can find on C70S6 Ultimate Tensile strength says 1000-1100 Mpa. 4340 for comparsion sake is 1440 Mpa. That is a 44% increase in UTS. 4340 is an alloy many aftermarket rods are made from. I do not know what alloy the machined cap rods are. But it deffinatly appears to me that if one is going for ubber power investing in 4340 rods might not a bad idea.

[Robertp]

Originally Posted by JOHNBOY

Well I apologize for saying the CR rods where PM. I thought they where. I do totally agree that the fractured cap is a superoir union over a machined cap. But the union does not appear to be the failure spot.

To back up what said about the real benifit of fracture caps over machined is cost. It is a better union but IMHO it was a cost move.

Quote below taken from http://www.corusautomotive.com/file_...CES_Proda5.pdf

"In fracture splitting, the big end cap is removed from the
body of the connecting rod first by notching (usually by
laser) and then by fracturing. The fracture splitting
process offers major savings in the through-cost of
connecting rod manufacture. A reduction of as much as
25% in plant investment costs and 35% in the
processing costs of machining lines are claimed."

The data I can find on C70S6 Ultimate Tensile strength says 1000-1100 Mpa. 4340 for comparsion sake is 1440 Mpa. That is a 44% increase in UTS. 4340 is an alloy many aftermarket rods are made from. I do not know what alloy the machined cap rods are. But it deffinatly appears to me that if one is going for ubber power investing in 4340 rods might not a bad idea.

Exellent info, are the vp rods made out of the 4340 alloy?

[WUnderwood]

Originally Posted by Timbeaux38

We post sheets and video anytime Wade farts at the track, but we lost this one

Sorry for the Derail, but since we are on a fact-finding mission about rods, we migt as well stick to facts

[Robertp]

Originally Posted by WUnderwood

Whats the fastest you or tim have gone? 15.0's

[JOHNBOY]

Originally Posted by Robertp

Exellent info, are the vp rods made out of the 4340 alloy?

I honestly do not know. I just used 4340 for comparision because you can get rods made from that alloy.

[WUnderwood]

where's those TIMESLIP(S!) cowboy?

[RacinDuallie]

I know they ran an 11.08, witnessed the run and aftermath of of fully thrashed fuel rail from a big psi spike...... Seen the timeslip too.


Never seen a 10- something slip or run from them though........

[WUnderwood]

Originally Posted by RacinDuallie

Never seen a 10- something slip or run from them though........

yep, it seems to be pretty mysterious, just like
-where is Jimmy Hoffa
-origins of Stonehenge
-the Bermuda triangle
-Area 51
-how a 600 hp truck can run 10s

[halerazor]

Originally Posted by JOHNBOY

"In fracture splitting, the big end cap is removed from the
body of the connecting rod first by notching (usually by
laser) and then by fracturing. The fracture splitting
process offers major savings in the through-cost of
connecting rod manufacture. A reduction of as much as
25% in plant investment costs and 35% in the
processing costs of machining lines are claimed."

we don't laser cut ours we broach them, same principle though. when that cracker hits you can feel the floor shake

[joefarmer]

My CR rods are also running fine in my 12v. They've survived a number of passes where nitrous usage was >8 lbs per pass. That's admittedly a little excessive, but still a blast!

[Robertp]

Originally Posted by WUnderwood

yep, it seems to be pretty mysterious, just like
-where is Jimmy Hoffa
-origins of Stonehenge
-the Bermuda triangle
-Area 51
-how a 600 hp truck can run 10s

I cant answer the first 4, but the last one is easy, but we cant give out our secret just yet. So keep listening to those astounding hp #s on the dyno and wonder why they cant run at the track. 900HP = 15's and 600hp = 10's. I guess less is more.

[Robertp]

[QUOTE=RacinDuallie]I know they ran an 11.08, witnessed the run and aftermath of of fully thrashed fuel rail from a big psi spike...... Seen the timeslip too.




Good point jeff, after the rail was fixed we added a bit more nos and we hit the # a few weeks after that. It's amazing what can happen with another 1/8 mile worth of good fuel psi.

[Robertp]

Originally Posted by joefarmer

My CR rods are also running fine in my 12v. They've survived a number of passes where nitrous usage was >8 lbs per pass. That's admittedly a little excessive, but still a blast!

Joe how much HP are you making? What et's are you running?

[jkretzer]

someone is getting defensive about self inflicted here-say! i dont think there was much of any kind of secret in that truck, facts are facts (well maybe lies about what was actually done to it). there are plenty of others that have more experience and have been "Leading Diesel Innovation" before some were even an itch!

Stirrrrrrn the pot!

[JOHNBOY]

Originally Posted by halerazor

we don't laser cut ours we broach them, same principle though. when that cracker hits you can feel the floor shake

I would love to see that in person.

[RascalMafia]

halerazor, where do you work?

[halerazor]

Originally Posted by feelmecummin

halerazor, where do you work?

i work at honda's engine plant, i'm a maintenance tech

[joefarmer]

Originally Posted by Robertp

Joe how much HP are you making? What et's are you running?

Mine dyno'd at 609hp/1000tq and ran 11.41@120 at 6280#.