factory rod???

[branch757]

hey guys gotta question. im going to be building my motor for around 350-400 hp (400hp being rare cases) im stuck on what to do with the rods. should i get the pauter rods or buy some factory one and get them shotpeened? ive herd the factory rods are pretty beefy. what do u guys think is the best choice for my goal.

thanks for any input

[Warped]

well ivan is putting down over 500tq w/ stock rods , i would say they are ok for what you want to do IMO

[250sx]

its prob ok to run the stock rod and you prob have more things to worry about(tuning/detonation) but I would hate for a rod to break at 400hp

[Ubernoober]

Well, it really comed down to this:This is an internal component not easily chaged once you have made a decision. Is it ok to fail even once? Can you afford the ones that claim not to fail? Is it worth it to spend money on the rods or on a fuel system that can guarantee no detonation?Its all a matter of choices. My opinion at that power level would be to get a nice set of Crower or Pauter rods. I can always upgrade external stuff later.

[MarkEmark]

Well, it really comed down to this:This is an internal component not easily chaged once you have made a decision. Is it ok to fail even once? Can you afford the ones that claim not to fail? Is it worth it to spend money on the rods or on a fuel system that can guarantee no detonation?Its all a matter of choices. My opinion at that power level would be to get a nice set of Crower or Pauter rods. I can always upgrade external stuff later.

Good point.

The factory rods are very beefy from the factory, both forged AND shotpeened....all that Ivan did, IIRC, is have them re-shot peened. You could even get them cryoed if you want. If you buy them brand new OEM they should be plenty beefy to handle the power, but again, it all depends if you have the money and if you want the peace of mind...I'm only lookin' to make around 330 whp and I've NEVER heard of stock rod failing in a KA-T yet.

[branch757]

yeah i think im going to buy a new set of rods and have them shotpeened. everyone i kno says that the ka rods are beefy enough to handle up to 400-450 so 350 should be good enough. hopefully my fuel system is up to par. im going with the boost designs stage 2 kit and im getting an emangei hope this will be enough

[WDRacing]

Especially if you keep the RPMs under 7500. The higher loads under high rpms will be the killer. I still haven't heard of anyone who had a tuned motor and has broken a rod do to weakness. Its always been an oiling problem or a bad bearing.

WD

[Ubernoober]

Few rods fail in compression, with bearing failure being the exception. Failure occurs in stretch. Rod failure or bolt failure. Minimize stretching stress by keeping it within the factory redline.

[UncleBen]

I'm having my rods shotpeened; they were pulled from my spare KA that used to be a turbo motor with over 400whp :/ I figure they need a shot of the peens again :p

I was partially wondering this same thing anyway, thanks for all the good info guys.

[fiznat]

I've gone pretty much all out on my project, new valves, forged pistons, ARP bolts (including rod bolts), all kinds of machine work goodies, the AEM EMS, nice turbo, methanol injection etc etc... and stock rods.

I was all ready to get some nice rods, but my machine shop guy (who, trust me, is VERY good at what he does) advised against it. Not only was he extremely impressed with the size/design of the stock rod, but he pointed out that stock KA rods are both forged AND shotpeened from the factory. Shotpeening a second time, he says, will yeild very little benefit.

As far as worrying about my rods failing, I am not too concerned about it, and I'm looking for over 400-450 RWHP. I HATE reving the KA out (it doesnt make sense power-wise anyways), and the factory redline is perfectly fine. There shouldnt be any reason why the KA rods will fail unless something else major happens: both myself and Ivan at Sound Peformance/Phat KA-T will prove that.

[WDRacing]

I want to increase the RPM band on my motor simply because of the Cam/turbo combo I'll be using. Having a 7200 RPM won't yield enough of a useable power curve. But the car isn't going to very street friendly. I probably won't see boost until 5500 or so RPM. So rods and balancing are a must have for me.

WD

[fiznat]

^^ Thats true. If you've got a gigantic turbo and you need the extra revs then I guess you have no choice-- but for people with small to medium sized turbos (which are fine for most power ranges people seem to be interested in here), stock redline is high enough.

[Warped]

what a waste it seems to have only full boost from 5500 to 7200

[MarkEmark]

^^ Thats true. If you've got a gigantic turbo and you need the extra revs then I guess you have no choice-- but for people with small to medium sized turbos (which are fine for most power ranges people seem to be interested in here), stock redline is high enough.

Especially when it's an S13 redline, which is 6900 rpm, compared to the S14 KA redline at 6500.

Correct me if I'm wrong, but I believe the only (major) difference between s13 and s14 engines were cams, so it's plenty safe to rev an s14 ka up to 6900 (if you have the rev-limiter removed) even though the factory redline is 6500....

Fiznat...where did you get ARP rod bolts for the stock rods? Did they need to be adapted to fit?

[fiznat]

Fiznat...where did you get ARP rod bolts for the stock rods? Did they need to be adapted to fit?

I got them through my machine shop... he took care of all the ordering so I really dont know how someone else might get ahold of them. Pretty sure they fit the stock threads as well, although honestly I dont really know.

[virus77]

Arp makes rod bolts for our application, will fit the stock rods.... I hope or i got ripped.

[98s14inaz]

After reading this thread I would say keep the stock rods, stock crank, upgrade pistons, new bearings, and have the whole assembly balanced. Factory internals should be just fine with the exception of the pistons (which are iffy). If the assembly is balanced you can rev higher. The KA loses all efficiency over 7200 rpm, it is stupid to rev it that high.

[branch757]

wow..this is some really good infomation. yeah i think that the stock rods should be able to handle the power im looking at with the right tuning. thanks alot

[WDRacing]

If the assembly is balanced you can rev higher. The KA loses all efficiency over 7200 rpm, it is stupid to rev it that high.

The KA simply requires a port job with new cams and a valvetrain upgrade in order to be efficient. In stock trim it's actually already falling on its face at 6500.

[Ubernoober]

"In stock trim it's actually already falling on its face at 6500"

Hey WD, is that why the front of my 240 is all scraped up? I thought it was from the previous owner banging the nose against curbs and parking bumpers. Heh

[branch757]

so if i want to rev past the existing redline the stock rods arent up to par??

[WDRacing]

The JWT ECU raises the rev limiter to 7200. So I'd say thats a good mark to stop at. But your losing power by then anyway without a set of cams.

WD

[hannibal]

Especially when it's an S13 redline, which is 6900 rpm, compared to the S14 KA redline at 6500.

Correct me if I'm wrong, but I believe the only (major) difference between s13 and s14 engines were cams, so it's plenty safe to rev an s14 ka up to 6900 (if you have the rev-limiter removed) even though the factory redline is 6500....

I think this is true. Doesnt the JWT ECU raise the redline to the same 7200 rpm for S13's and S14's?

[250sx]

sustained high rpm kills rods right? Just dont glue the pedal to the deck.

[MarkEmark]

I think this is true. Doesnt the JWT ECU raise the redline to the same 7200 rpm for S13's and S14's?

Yep, my redline is not 7200. I've never brought it past 7000 though, and it's not making power up there anyway so there's no need to bring it past 6500 unless holding out second gear for a faster 0-60 time...

[C-Kwik]

While tensile loads on a rod (and any metal part for that matter) can fatigue the part, I'm not sure what the limit of the stock KA rod is. From people who seem to be involved with NASPORT KA build-ups, including JWT, they say the bottom end exhibits a great deal of vibration at about 7500 RPM. So to go beyond this point, you'ld likely need many changes to accomodate it.

If you plan to use stock rods and operate at the upper end of it's known limits, you may want to balance them and remove cast flashings, if any, if you have the opportunity.

Personally, if it were me, and I had the resources, I would go with stronger rods. But I won't shut down using the stock rods. They are plenty strong for most on here.