Stock rods versus forged

[ArcadeMod]

Ok so Ive got my ka24e out, i have all my lower and top end parts stockpiled. I got some toga hp bearings and I went with wiseco coated forged pistons in order to withstand a decent amount of boost. This being my first build im unsure of whether or not I should spend some extra loot and get forged rods. Can my stock rods handle forced induction? Just looking to see some opinions. thanks -Steve Vinci - 89 notchback

[elgarvo616]

it depends for what kinda power your going for. if your gonna be making more than like 300whp id say put em in just for reliability's sake

[S13Coupe]

I'd say if you want to save some money, just get the stock rods shotpeened and put in ARP rod bolts. Stock rods that have been beefed up a little like that have been proven to be good up near 400whp....assuming that you have the car tuned well. But if you're targeting more than 350whp, I'd dish out for the rods. Better to spend the money now, than it is to have to do it all over again.

[ArcadeMod]

Ill probably go with the shotpeening and new arp hardware method, it never even occured to me that I could do that. Thanks.

Steve Vinci

[SimpleEnigma]

If i am not mistaken I believe that the stock KA rods come shotpeened from the factory.

The stock rods are good for up to about 400whp before people bend them. If you were really looking to avoid bending a rod/reliability, i would prolly just dish out the cash now and get forged rods to go along with your pistons, simply for safety's sake. that way if you get a bigger boost itch you can up the power without having to worry about breaking a factory rod.

[S13Coupe]

If i am not mistaken I believe that the stock KA rods come shotpeened from the factory.

I'm not exactly sure what the shotpeening process is, but the way someone explained it to me was that it was just a way to freshen up old rods so they're back to their original strength. But I'm not sure if that's right.

[spider_slayer]

someone correct me if i'm wrong but shotpeening is firing many very very small pebbels at a metal object at extreamly high speeds causeing microfractures in the alloy. somehow the micro fractures allow the overall structure to endure more stress.

[InsanityInc]

You're half right. That IS the process of shot peening. However, that's not the purpose of it.

The purpose is that it's making the casting more consistent by using a high intensity localized compression across the entire surface. More consistent metal is stronger metal.

[SimpleEnigma]

Shotpeening also makes the exterior layer of the rods material much much harder than the interior. This is due to a phenomena known as work hardenings or strain hardening or cold working. The downside to a metal being extremely hard is that it is also extremely brittle, so the metal would actually suffer "catastrophic" (i.e. the metal breaks like hard plastic would) failure instead of a "typical" ductile style (the metal streches and bends, then breaks).

The advantage to shotpeening, besides cold working the metal and making the exterior layer harder and stronger is that it also allow the metal to retain some ductility.

[corn322]

The forged rods weigh less.zerothread?id=151943

Not a whole lot, only 3 oz. less each.

[Florida240sx]

If you plan to have over 325rwhp, then get new rods.Even at that point.For safety's sake I would put in the forged because you'll get the boost itch and want to crank it up. Better to spend $600 now then 2500 for a new built engine. Soem ka rods have lasted over 400rwhp some have gone bad at 350.It depends on how well they oil has cooled them in their life span.

[Bigvinnie]

Shot peened sucks, and isn't true forging....The type of steel used is almost just as important as the forge it comes in.