Shot Peened Std Rods V Forged Rods

[The Bogan]

One of my quotes for a engine rebuild has the std 25 rods being shot peened and another has forged items, Being a cheap arse i like the idea of the shot peening, but whats the difference, I watched a show on TV the other day and they were shot peening std rods for a Chevy motor.

Could someone please explain as one shop says they will be fine whilst another says they wont.

Thanks. MLR

[bnr#@]

What power are you after from them?

[maximajim]

Shot peening is done to prevent stress fractures at the surface of a part. For high power levels I would undoubtedly use forged parts.

[The Bogan]

Id like over 300atw reving to 8k.

Thanks, MLR

[SteveL]

Stock Nissan rods are forged. I don't know of any Nissan engine that doesn't used forged rods, although some manufacturers have been experimenting with advanced powder met techniques.

Shot peening introduces a surface compressive residual stress which resists crack initiation and growth. If it's not done properly it can actually introduce defects.

In any event the weak point is not the rod, but the rod bolts, unless the rod has some manufacturing flaw (NDI is mandatory).

Whether you need to go to upgraded rods depends on expected power level as already suggested.

[The Bogan]

Sounds good, they will have ARP stud bolts installed.

Thanks, MLR