Forged Rods vs. Stock?
10-24-2005, 11:14 PM
#1
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Forged Rods vs. Stock? For a naturally aspirated LS1 or LS6 there are some definite advantages to forged pistons, but what about the connecting rods?
Most of us already know that the earlier units need better bolts, but let’s put that issue aside for a moment and assume we are talking about the late model rods. Just how good are the factory rods and when should you consider upgrading to aftermarket factory rods?
Most of us already know that the earlier units need better bolts, but let’s put that issue aside for a moment and assume we are talking about the late model rods. Just how good are the factory rods and when should you consider upgrading to aftermarket factory rods?
10-25-2005, 06:27 AM
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I think the rods are quite stout to be cast rods. GM casts them from powdered metal, making a more uniform and controllable piece. To the point that they don't need balanced, thus no balancing pads.
Clueless on when you'd break one, though.
Clueless on when you'd break one, though.
10-25-2005, 04:35 PM
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The stock connecting rods are extremely strong. Con rods made beginning in '01 used a stronger, re-designed rod bolt. These rods have been used in engines producing over 500 HP.
The OEM flat-top pistons are fine for stock applications, but their eutectic construction does make them susceptible to damage from detonation.
The OEM flat-top pistons are fine for stock applications, but their eutectic construction does make them susceptible to damage from detonation.
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10-25-2005, 04:55 PM
#8
I'd recomend rod bolts after 6000rpms. The rod bolts really don't fail because of power, it is because of rpms. I'd say the connecting rods are good for at least 550rwhp, now the rod bolts on the other hand, you better get some katech ones. ARP makes some as well, but I'd go with Katech.
10-25-2005, 05:20 PM
#9
Originally Posted by 777
I'd recomend rod bolts after 6000rpms. The rod bolts really don't fail because of power, it is because of rpms. I'd say the connecting rods are good for at least 550rwhp, now the rod bolts on the other hand, you better get some katech ones. ARP makes some as well, but I'd go with Katech.
10-25-2005, 06:04 PM
#10
Originally Posted by 618HAWK
Looks like I am walking a tight line here, not that my setup sees thoughs hi rpm,s that often.
Your sig says 2001. I believe the 2001 and up have better rod bolts so you dont need to worry.
10-25-2005, 07:15 PM
#11
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I have used the stock rod with A1 bolts in road race engines with great results. 7000 rpm with 500hp at the crank. The stock rod bolts that won't fall out of the caps are the better one's. If your rod bolts come right out of the cap, you should replace them.
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10-26-2005, 01:09 AM
#12
I don't think there is a 'cast' connecting rod. I don't think I would call powdered metal 'cast'.
There are three issues in the rods (and bolts): power, duty cycle, and risk. Stock is designed for some margin (20%? 50%) above stock power/rpm levels. However is also designed to live close to the limits of the stock power levels for an indefinite duty cycle with zero risk of failure within manufacturing tolerances. Clearly, a bad one may get out now and then, but it is rare.
For higher power levels, what duty cycle and reliablity do you want? And at what weight. Before the fuel mileage mandates and performance wars, You could make the part fairly heavy At fixed engine speed on a dyno, a heavy piece is as good as a light one. However, for rapid acceleration, weight counts. And light weight reduces power/rpm limits and duty cycle.
If your spending money on rods, weight (500-600 for 6", racing 6" rods (steel 4130M) are under 500gm. with Honda or smaller journals) is as important as power.
There are three issues in the rods (and bolts): power, duty cycle, and risk. Stock is designed for some margin (20%? 50%) above stock power/rpm levels. However is also designed to live close to the limits of the stock power levels for an indefinite duty cycle with zero risk of failure within manufacturing tolerances. Clearly, a bad one may get out now and then, but it is rare.
For higher power levels, what duty cycle and reliablity do you want? And at what weight. Before the fuel mileage mandates and performance wars, You could make the part fairly heavy At fixed engine speed on a dyno, a heavy piece is as good as a light one. However, for rapid acceleration, weight counts. And light weight reduces power/rpm limits and duty cycle.
If your spending money on rods, weight (500-600 for 6", racing 6" rods (steel 4130M) are under 500gm. with Honda or smaller journals) is as important as power.
10-26-2005, 03:05 AM
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Odds are, if you think you're making enough power to need forged pistons, you might as well pony up the extra $ for the rods and be able to sleep a little better at night.
10-26-2005, 03:14 AM
#15
Originally Posted by Xtreme57
Odds are, if you think you're making enough power to need forged pistons, you might as well pony up the extra $ for the rods and be able to sleep a little better at night.
10-26-2005, 03:27 AM
#17
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Originally Posted by 618HAWK
OK
With all that said any recomendations for a good rod that wont brake the bank. With a long life (duty cycle). Whcih could support 600-700 Hp, looking into future mods.
With all that said any recomendations for a good rod that wont brake the bank. With a long life (duty cycle). Whcih could support 600-700 Hp, looking into future mods.
. I've put over 3000 hard miles on the new setup this summer. A decent rod for the price are the Callies Comp Star Rods. I've seen them go into some fairly stout setups and no failures.
Last edited by LS7SS; 10-26-2005 at 03:32 AM.
10-26-2005, 08:49 AM
#20
Originally Posted by 777
I'd recomend rod bolts after 6000rpms. The rod bolts really don't fail because of power, it is because of rpms. I'd say the connecting rods are good for at least 550rwhp, now the rod bolts on the other hand, you better get some katech ones. ARP makes some as well, but I'd go with Katech.
Dude, the stock ls1's have a 6200 rev limit. The ls6's have a 6500 rev limit, both using the same rod bolts (in later years anyway). I dont see the need to rod bolts at 6K. There are plenty of folks spinning as high as 7K on stock rod bolts, although that would be pushing my comfort level. I personally have a 6800 rev limit, although I rarely shift past 6400. I havnt thrown a rod yet, knock on wood.