The kits from INDY still use Eagle rotating assemblies. Recently my machinist put together a 572 for another customer. INDY Block, 572-13 heads, and it made 1017hp, and was still climbing, when the machinist said that's enough... He wasn't worried about the rods, but didn't like the Eagle crank spinning any higher than it did.

The kit I used in mine that just blew was a K1 Kit from (defunct) Flatlander Racing. K1 is now part of Wisco.

Nice looking kit. Needed nothing done to correct anything balanced nice also. By they way over the course of several freshen's I replaced the ARP2000 bolts with L19.
I can't prove a rod broke initially or if it was a wrist pin as both were destroyed.

This was Tom Molnar who developed the K1 stuff, copied from another forum and may be helpful to this discussion..

We are frequently asked about power ratings for rods but this is a very difficult question to answer and it is nearly impossible to put a meaningful power rating on them. First off, while many people do rate rods by power, there is no certain power level that when reached, the rod will fail. Power is produced from the expanding gasses in the combustion chamber pushing down on the piston which in turn pushes down on the connecting rods. While there are certain situations that could lead to failed rods due to compressive loads, rods generally do not fail due to power loads. If they did, they would experience severe bending to the point of permanent deformation prior to breaking.



Fact #1 - When you see a broken connecting rod where there is no seizure of the bearing or failure of the piston/pin/cylinder wall, look closely and you will see that the rod was actually pulled in two. This high tension pulling load on the rod takes place at TDC on the exhaust stroke and is caused by the piston trying to continue up the cylinder wall and through the cylinder head, and the crankshaft trying to pull it back down. Keep in mind there is no power being made on the exhaust stroke. The heavier the piston, longer the stroke and the higher the RPM, the more pulling load is placed on the rod. Because of this, you could build two identical engines that both make the same power but if one has heavier pistons, you run a much higher risk of breaking the rods in this engine.



Fact #2 - When you look at a Dyno sheet, you will see that as the RPM is taken past peak power, the power falls off however, most of us have seen engines that have had rods break when over revved. If power broke rods, they would never break due to being over revved.



Fact #3 – If you ever see anyone who has broken a connecting rod at a dragstrip, you will notice it is normally after they cross the finish line. In a circle track engine, the rod will break just before they enter the corner. In both of these cases, the rod breaks when the throttle is closed. Since you are not making more power when the throttle is closed, you have to ask the question, why the rod broke at that point.



Once again, power does not break rods and people that are rating rods by power are using what I refer to as a “Brown Number”. A Brown Number is a number they pulled out of their rear end just to make the customer feel good and to get them to exchange their hard earned money for their product. At K1 Technologies, we use the best computer technology and draw on over 28 years experience in rod and crankshaft design to insure the rods we manufacture are correct for the application.

Dave

I wish I said that.

Oh, wait. I did.

Good read from Molnar - thanks for posting.

He doesn’t talk above the crowd like some other people. Straight to the point.

Well that’s a good reason to let the piston hit the head, can’t stretch past the head

Dave

Well it was funny to me

Me Too...

Dave

Perhaps the weight of the 7.100" rods is reduced by making the pin end of the rod narrower.
This table from Molnar web site. 1.140" vs 1.065"

Can anyone measure a 7.100" H-beam rod from another manufacturer to compare to my measurements?
The catalog weight of these is 832 grams.

Carrillo 7.1 h beam 1.2 wide, .65 thick, and .13 beam. Big end and small end same .992 and 1.06
Eagle 7.1. ............ 1.375 wide, .627 thick and .090. These eagles were mopar width, forgot the measurements on the way from garage to the house

My K1 rods from my 500 inch blower motor 9.98 deck, and my Oliver from my 572 B1, 10.225 deck.

[img]https://i.imgur.com/VWqxgO6.jpg?1[/img]

Dave