When we talk about building these gen III engines the discussion comes to ARP studs in the bottom end. Everyone agrees that these studs are a good idea. If you are building one of these things for a power adder like a supercharger, when are billet main caps a good idea? Is the added expense of purchasing the caps and then machining worth the benefit?

My builder says over 650 hp it's a good idea, at 750 Hp it' better idea,800 it's a requirement. I know he uses them on all of the 4.25 stroke builds he's done. My 408Ci (5.7 based) makes 725 hp and has a older set of Pro-Gram , which now are manufactured/sold by Billet Speed works.

The demon is 840 HP with regular caps.

And your point is?
if you are going to invest 5-12k into a new engine spend the money for every bit of insurance.
Demon also doesn't have ARP mains or Rod bolts......are you going to tell me just because that 8XX hp engine doesn't use them you won't?
Demon blows up ...you go back to the dealer for warranty.

Hudsonshornet's engine takes a crap because the mains walked or he decided to go with stock rod bolts because the Demon uses them? .....where is he going to go for warranty ?

We recommend them over the 750HP mark, or anything getting a power adder that way when the customer gets bored and turns it up, the caps are there.

Slowly whittling a set for myself, if accurately made the only required machine work should be an align hone, which you would do if installing studs anyway.

The factory would be upgrading if it was a concern because they don't want to replace engines because of those caps, "if they were a problem". I just think they are pointless under 800 HP. I am all for upgrading weak links, I just don't see them being a weak link. The things that were weak links on engines of past (aluminum mains on BB anybody) tend to be though of as weak links on modern engines even though the factory adressed them and they are no longer an issue, same as how we no longer need aftermarket ported heads for 600HP engines. If you start going over 800 HP then maybe upgrade the caps butt honestly I have never heard of a main cap breaking on one of these at any level and plenty of people are adding boost and nitrous to these things without opening the motor.

Main caps do break.
If you have ever seen how porous these G3 caps are u will understand why they break.

I say if you have a power adder its good insurance.
Im in the process of getti g a production run of billet main caps done.

Also the Demon engine has ARP rod bolts

How many companies are making billet main caps for the gen 3 hemi? Anyone have feedback on each companies quality?

I Know Arrington sells their own, Not sure who makes them, I've seen a few setts and they look good, My builder has used them a few times ...he just shrugs his shoulders and says ...There Main caps.
I have older pro-gram caps in my G3 can't complain .we freshened up the short block this past February after 18k miles and 500 runs and the only marks in the DLC coated Mains bearings was from the Dial bore gauge from the initial build.

I've seen a few 650-700 Hp G3s pulled apart with either #2 or #3 Broken at the stud like the one you have in that photo, as for the Demon.....I've seen my builder tear 4 of them apart so far and looks like the factory must of missed them Memo on on the ARP main studs.

They look good, the bolt in the center is that for a girdle ?

I imagine that is to screw in a slide hammer to pop the caps out of the block at disassembly.

Looking at the heat scoring on the other caps I would say something else was going on and the broken cap was probably the result of something else.

That would be correct

The powdered metal caps on every block I have taken apart have not impressed me. The parting line surface is not machined after sintering and when I set them on a surface plate they had a fair amount of rock. Even on a stock rebuild I would dust that surface and then align hone.

The engine had nothing else fail but the cap. It was a pullied up Hellcat

No not ARP main studs just ARP rod bolts

Are the Arrington caps the only ones that don't require align boring? My local machine shop does not have the boring machine, just an align hone.

I purchased Arrington caps and they had to be line bored. I bought them because it said line hone only. They were a good .060 small. I would call and verify line hone only.