What engines use the 7.8 DME ?

[Quadcammer]

Id skip the rods and just install a set of arp bolts in your stock rods. The rods dont break, the bolts fail or the bearing spins causing the broken rod

[PaulE]

Originally Posted by Quadcammer

Id skip the rods and just install a set of arp bolts in your stock rods. The rods dont break, the bolts fail or the bearing spins causing the broken rod

I like that. If I stay with the stock rods, will definitely use ARP rod bolts. What causes bearings to spin? Isn't it due to loss of lubrication? Does Carillo CP rod offer a more precise bearing fit than the Porsche powdered metal cracked cap rod that would provide a more precise fit and maybe help prevent spun bearings? Am I getting into how many angels can dance on the head of a pin territory here?

[Gilles]

Originally Posted by PaulE

I like that. If I stay with the stock rods, will definitely use ARP rod bolts. What causes bearings to spin?

The low quality rod bolts used by Porsche do tend to stretch under constant high rpm's, but if you use good quality bolts (ARP) you would be ok, specially since you are not trying to build a 'low cost racing engine'' and you can save a good amount of cash (perhaps for a nice head prep..?)

[Quadcammer]

Originally Posted by PaulE

I like that. If I stay with the stock rods, will definitely use ARP rod bolts. What causes bearings to spin? Isn't it due to loss of lubrication? Does Carillo CP rod offer a more precise bearing fit than the Porsche powdered metal cracked cap rod that would provide a more precise fit and maybe help prevent spun bearings? Am I getting into how many angels can dance on the head of a pin territory here?

I don't think the issue is the rod bearing clearance, but rather due to heat, potential loss of oil pressure due to starvation/foaming, oil viscosity dropping, etc.

You can certainly try to adjust bearing clearance, but I'd say thats less of an issue.

[911monty]

I'm probably wrong here but my last experience with stock powdered metal cracked cap rods was the rod bolts cannot be replaced because they are integral to the cap alignment. Has that changed?

[Gilles]

Originally Posted by 911monty

I'm probably wrong here but my last experience with stock powdered metal cracked cap rods was the rod bolts cannot be replaced because they are integral to the cap alignment. Has that changed?

I believe that the rod bolts can be upgraded but the rod caps cannot be swapped as you mentioned.

[jsceash]

Originally Posted by Gilles

I believe that the rod bolts can be upgraded but the rod caps cannot be swapped as you mentioned.

ARP Bolts are an upgrade but the caps can not be changed or interchanged. The carrillo rods are stronger, but better yet they are lighter than the stock rods. The Original rods vary in weight by several grams. My set of Carrillo rod were within .5 grams of each other.

[Gilles]

Originally Posted by jsceash

ARP Bolts are an upgrade but the caps can not be changed or interchanged. The carrillo rods are stronger, but better yet they are lighter than the stock rods. The Original rods vary in weight by several grams. My set of Carrillo rod were within .5 grams of each other.

As a low cost (huge..) improvement, you can only install the ARP studs and rebalance the OEM rods...
Of course, being there considering the Carrillo rods would be a 'huge step up' 😁

Honestly, originally I budget on my engine rebuilt (using LN Nickies) a set of Carrillo's along with a head work from Hoffman Automotive

However, it is difficult to draw the line, that is the reason I said that you could 'only replace' the conrod bolts with ARP's to keep te cost down..
.