Stock Connecting Rods Safe RPM Limit?
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So lately I've been thinking about the rods in my LT1 that I'm slowly building. I'm getting the block bored to a 355 today and already bought the pistons for it just planning on using stock rods with them. But I really can't decide what kind of rpms I want to spin this motor to. I definitely plan on buying ARP rod bolts at least but I'm not sure what stock rods with ARP bolts could reliably spin to in a daily driver that occasionally sees the track? Or if I should go ahead and save up a little more for new rods which I would like to hear some options on. I plan on using a Lloyd Elliot 226/232 .578/.574 camshaft and figured it would like at least to spin to 6400-6500rpms
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Yep. You will need to get the rods resized, so there then poses the question of whether or not it would be more expensive to get new rod bolts/resized compared to getting a set of new rods with ARP bolts? Talk to your builder.
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I just left my builders house and that's what him and I were discussing. I thought rods were a lot more than they are but he showed me some forged Scat I beams that also include ARP rod bolts in a Competition Products catalog. I think these are it. If so, I'd like to try these out http://www.competitionproducts.com/S...nfo/SCA25700P/
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everything said sofar is fine BUT one critical part of understanding this has been completely neglected. Piston WEIGHT is HUGE in determining how much stress a rod will see. I know a lot of guys like to pick out a cheap antique TRW piston PN that is MUCH heavier than stock, I would not want to trust stock rods with RP bolts and those pistons above 6500 much, but stock rods with ARPs and stock pistons has been shown time and time again to be a great budget setup solid at 7000rpm.
The most stress a rod sees is when it has to change the piston direction from up to down, the lighter the piston the lower the stress.
The most stress a rod sees is when it has to change the piston direction from up to down, the lighter the piston the lower the stress.
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Just to go on the safe side, I'd definitely (like mentioned) get some decent rod bolts and have everything balanced accordingly. Most of the failures I've seen are from negligence, not from actual part failure.
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many of us have taken stock shortblocks to 7000rpm, but it is a reasonable idea to recondition the rods first if you have the budget and time.
Again piston weight matters. I wouldn't go hanging a heavier piston on stock rods and spinning high. Stockers are about 532grams
Again piston weight matters. I wouldn't go hanging a heavier piston on stock rods and spinning high. Stockers are about 532grams
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We weighed the pistons I bought a couple nights ago and they were right around 550 grams. I just bought some Speed Pro Hypereutectic pistons because I originally didn't plan on buying any at all since i bought a 93 LT1 that was suppose to be good and healthy. But we took that lt1 apart and found that it had water in all the cylinders causing a bunch of rust that we couldnt hone out. So I have to get it bored .030 now. But I think we're pretty set on those Scat rods since they're only like $249 and include ARP Rod bolts with them
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Whatever RPM you spin it to make sure it's what the engine needs. Some think it's a good thing to spin to the moon regardless of where peak HP stops in the RPM band, which accomplishes nothing other than slowing you down. Good luck on the build.
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Thanks SS RRR! The machine shop is so backed up that it will be 3 weeks before they can get my block back to me which sucks, but it will give me time to buy the rods and everything else I need. Since we've decided on these rods and everything in the bottom end, I think I might go with a larger cam since I plan on getting LE2 heads down the road.
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I got a short block that had those cheap,dumb and super heavy trw pistons. With stock rods, heads cam and six lbs of boost. Made over 500rwhp for six years and never failed. You will be fine. I bet even with stock bolts.