Stock connecting rod durability?
Thread Starter
Joined: Oct 2004
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From: Vance, Alabama
Stock connecting rod durability? Like the stock cranks, I havent seen anything really post or threads on the net about a rod failure. How many failures really happen? What about with upgraded bolts, are they less acceptable to failure then? The reason Im asking is most people upgrade the rods when they buy forged pistons but is it really needed in post applications. I believe in most applications if the stock rods are in reuseable shape, throw some ARP bolts in and let er go if the desired piston is availible for the 6.098 rod. If it has the wrong size pin just bush the stock rods to that diameter.
A lot of people see it as if you have it torn down to replace the pistons might as well not leave the rods in to be the weakest link. Plus a lot dont feel too good about spinning the stock rods too high, reguardless of rod bolts or not.
I think most buy forged rods because they needed a longer rod anyway. But, the powdered metal rods are way stronger than any stock cast rod and I've seen some pretty high HP (400-600 hp) motors still running cast rods. I'd guess the stocker with good bolts are good for 600-800 hp in a NA application. But that guess will come at a pretty high price if it's wrong and I trash a big$$ block and heads.
Launching!
Joined: Jun 2005
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From: longview, tx
I think you're probably right, Bo, although I don't have any facts to back my beliefs. The aftermarket likes us to believe that stock is inadequate and we need 4340 everything. Now if I was building a 7000 grand buzz bomb that was gonna get dragged a lot, I'd probably throw some rods in it but for a daily driver, I'm gonna stick with the stockers.
The LS1 powder forged rods are the strongest OEM production rod GM has ever used (except for LS7 titanium rod) in a production V8. In 2001 all LSI engines from the factory used newly redesigned rod bolts because of some rod bolt failures GM encountered in ASA racing division the prior years. But when rebuilding use top quality ARP rod bolts. They are relatively inexpensive and are good insurance against a major engine catastrophe.
Last edited by gollum; Aug 12, 2005 at 02:50 PM.
These will work and are plenty strong enough for a 383 stroker motor but you will need custom pistons for the shorter rod and 4" stroke combination. Why no one lists a piston for this combo is plain dumb.
Last edited by gollum; Aug 12, 2005 at 02:54 PM.
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If you're spending the $ to do a 383 stroker, why in the hell wouldn't you spend $500-$600 on a set of aftermarket rods (which come w/ good bolts) and use a cheaper set of forged off the shelf pistons, vs. spending the money on APR rod bolts for the stock rods and more money on custon pistons???
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Verdad Gallardo Thread Starter
Joined: Oct 2004
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From: Vance, Alabama
When you are building a stroker its more convenience for the rods to come with it but there will be a time when less expensive parts will be available like pistons and cranks so that more people will be able to afford to build up an engine and some may choose to stick with the production rods. SBC has many pistons available for stock rod applicationa and I believe the LS1 will eventually be the same. I am going to use the stock rods in my 422- the pistons are for 4.00 stroke/6.100 rod application. I have the pistons and have 3 sets of stock LS1 rods so all I have to do is buy an Eagle crank 
I'd suggest you rethink your plan Bo. While I'm sure this combo will work, those factory rods are going to see a lLOT more stress in your big bore stroker than they'll ever see in a 346 (all things being equal). Increasing the stroke and using larger (heavier) forged pistons is really going to push those rods to the limit. I don't think I'd even consider spinning that combo past 6200 rpm.
Unless you're building a big inch low RPM engine, I'd highly suggest you use better aftermarket rods... why take a chance for the small difference in money???
Unless you're building a big inch low RPM engine, I'd highly suggest you use better aftermarket rods... why take a chance for the small difference in money???
TECH Junkie
Joined: Nov 2001
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From: Chi-Town
i stuck with the stock rods. i just didnt have the extra 500 bucks to plop down on a 400 hp budget motor that wont ever see nitrous. if i were building an all out drag motor, or one that cost upwards of 5K+ then i would throw them in. if you have th e money though, just throw them in for the added safety 
i just like living on the edge. and if the rod does go, i have an excuse to build a new, bigger engine 
i just like living on the edge. and if the rod does go, i have an excuse to build a new, bigger engine 
~580rwhp (TH400/8"converter) on stock rods w/arp bolts here, shift at 6700rpm. This motor was done before cheap aftermarket rods were an option and its still going.. If I do a new shortblock it will have aftermarket rods most likely, for what they cost its cheap insurance.
Thread Starter
Joined: Oct 2004
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From: Vance, Alabama
I have seen your point, Wet 1, and have thought things through on +s and -s on the stock rod thing. I will not have really any money in this venture and also want to see the outcome of the stock rods in an engine like this. I will never spray it or boost it so its not really going to be stressed and its gonna be a daily driver that it see no more than 6500 rpm. I think the stock rods are well made pieces and also like livin on the edge like DriveATransAm 
. I have built many engines with prepped stock rods just not a LS1 yet and this would be the biggest test of such application. Besides, we're hotrodders here right- work with what ya got and run what ya brung
. I have built many engines with prepped stock rods just not a LS1 yet and this would be the biggest test of such application. Besides, we're hotrodders here right- work with what ya got and run what ya brung Last edited by Bo White; Aug 14, 2005 at 01:00 AM. Reason: Cant spell lol.
Teching In
Joined: Dec 2004
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From: Australia
My engine builder "Aussie LS1" tells me that over 7,000 RPM will result in the rods stretching and going out of round. He has personally witnessed this. I have no reason to doubt him as his LS1 turn 8,000 RPM and runs Crower Sportsmans, just as my new combo will.
Originally Posted by Bo White
I have seen your point, Wet 1, and have thought things through on +s and -s on the stock rod thing. I will not have really any money in this venture and also want to see the outcome of the stock rods in an engine like this. I will never spary it or boost it so its not really going to be stressed and its gonna be a daily driver that it see no more than 6500 rpm. I think the stock rods are well made pieces and also like livin on the edge like DriveATransAm . I have built many engines with prepped stock rods just not a LS1 yet and this would be the biggest test of such application. Besides, we're hotrodders here right- work with what ya got and run what ya brung
. I have built many engines with prepped stock rods just not a LS1 yet and this would be the biggest test of such application. Besides, we're hotrodders here right- work with what ya got and run what ya brung I think you are on the right track Bo. With your future 422 I think the rods will work if you keep RPM's under 6300. A lot of people will be surprised when it stays together. Now go find somone that will make you some custom pistons.
BO,
The great NASCAR engine builder Smokey U. once stated in a book I read. The most important part of a racing engine rebuild is the connecting rod. In some classes where you are limited to using stock rods careful attention to detail is critical, especially the big end of the rod.
Lenginfelter performance blueprints every crate LS1 engine used in ASA racing. They are the ones I would call and ask questions concerning inspecting and rebuilding your rods.
The great NASCAR engine builder Smokey U. once stated in a book I read. The most important part of a racing engine rebuild is the connecting rod. In some classes where you are limited to using stock rods careful attention to detail is critical, especially the big end of the rod.
Lenginfelter performance blueprints every crate LS1 engine used in ASA racing. They are the ones I would call and ask questions concerning inspecting and rebuilding your rods.
Last edited by gollum; Aug 13, 2005 at 11:59 PM.
Thread Starter
Joined: Oct 2004
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From: Vance, Alabama
I already have the pistons which is why Im heavily considering using the production rod in this application. I also believe Smokey, David Vizard, Grumpy Jenkins and other old schoolers on the importance of a properly built factory rod- I have 24 production LS1 rods to choose the best of 8 out of. I also trust "seasoned" production rods since most factory SBC rods after they have been ran will need resizing but after they have been resized one time they rarely need resizing again if they engine is tore down later on again and checked- seasoned rods hold their shape a whole lot better than new rods that hve never been ran. The structure of the rod is better because of the stress relieving that happens during the heat cycles and vibrations of a running engine. Now, of course they will have limits like everything else- I just believe I will not put them in a situation that would find those limits.
Thread Starter
Joined: Oct 2004
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From: Vance, Alabama
The piston weight is about the same but the longer stroke will increase piston speed and peak speed at mid stroke so I would probably say 6500-6700 is about it. It is also depending on how long the engine will be at that rpm as well, being that its going in my vehicle it probably will only be at that kind of rpm until the tranny can engage the next gear 
How much money will it cost to have LS1 rods rebuilt by a pro. Seems it would require less labor because you would not have to shave the caps. Simply hone oversize for the correct bearing fit after new ARP bolts are installed and torqued.