7000rpm redline, what does it really take? (rotating assembly)
LS motors rev up there all the time with stock rotating assembly pieces.
(nodular CAST crank, powdered rods, hyper pistons...)
I'm not talking a 700hp strip motor, I'm talking a nice 383/406 range gen 1 sbc with the appropriate top end to shift ~6800rpm. Say 550-600hp.
I've often heard that it is the rev's not power that kills motors. True?
Well can the current (equivalent to stock) aftermarket stuff take the test?
Hyper pistons, cast cranks?
We all build big but is it overkill or do we really need the forged billed rods while the 06 Vette redlines at 7000rpm STOCK.
(Stock C6: nodular cast iron crank, powdered rods, hyper pistons...)
Obviously, I am leaving out a solid roller cam, or the CTS-V 7000rpm lifters, or rev-kits and so forth to handle valve float, I'm just talking bottom end strength here.
You are correct - many of us go overkill "just to be safe" or to "protect the investment" or because we want the best parts available. Many times it's not necessary.
The key here is using high quality parts. The factory uses hyper pistons even in the 505hp 7000rpm ZO6 engine, but they're very high quality pieces. Not all hyper pistons are the same. Mahle makes a great piston, but you're more likely to find forged in the aftermarket than hyper. For higher rpms you want something that is both lightweight AND strong (piston speed increases with rpms, which creates more stress on the piston), and that combination is hard to find in a hyper/cast piston. I don't think KB recommends going over 6k rpm with theirs, for instance.
And there is nothing wrong with a cast crank for a strong street engine. Note however it is "nodular iron", not "nodular cast iron". Nodular iron is akin to cast steel (as opposed to forged). It's still a steel crankshaft, and this is a point of confusion for many. What is more important about the strength is a generous radius at the edge of the journals, and you don't find that alot in the early factory cast cranks.
The weakest link in the bottom end is the connecting rod, and that is usually what breaks first. Today's powdered metal rod is much better than the earlier factory forged steel rods - they're good pieces.
Are you sure the stock (base) C6 has a 7000 rpm redline? Could be, I don't keep up with it all, but I know that was advertised for the C6 Z06 427 engine, which leaves me to believe the base engine doesn't have that high of a redline. The Z06 engine does have hyper pistons, but has a forged crank and titanium rods...
Again, the key to high rpm longevity is lightweight and strength, and you'll find the best of both only in the higher quality pieces.
I might add that the factory spends alot of $$ testing and evaluating parts and working closely with manufacturers to develop them. It's cheaper for us as individuals that don't have R&D budgets to spend more money on higher quality pieces for the safety of knowing what you're getting.
Thanks, yeah I checked (this post was born out of some bench racing going on last night) and you are right, the z06 is 7000rpm. The LS3 is 6600. So not quite as high.
We were just talking about how the stock motors are reving to where we would only put forged lightweight components and talking about necessity and OEM vs aftermarket tech.
I was mistaken on the crank being cast, my bad.
With some of the heads coming out now, the lure to LS motors from SBC is not as strong as it was (considering the costs at least) however being able to buy a motor from GM with 7k redline and all the durability testing associated with it is quite impressive.
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7000rpm redline, what does it really take? (rotating assembly)
