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Build forged shortblock for boost using existing LS6 block?

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Old Aug 24, 2025 | 10:17 PM
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Default Build forged shortblock for boost using existing LS6 block?

I've got a 2004 Z06 with a Vortech Ti V3, TFS 220 heads and BTR Centri cam.

I'm wanting to explore going ahead and doing the shortblock so that I'm done with it, but am not sure if I should just utilize the shortblock that I already have and put a rotating assembly in it, or just buy a forged shortblock from one of the vendors?

It seems that I can save some money by just going with a rotating assembly and then having an engine shop somewhat local to me to do the machine work and put it together. I'm shooting for 800 or so rwhp out of the build.

What do you guys think? The factory shortblock only has about 9,000 miles on it, so it's in good shape.

Thanks!
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Old Aug 29, 2025 | 09:01 AM
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Only reason not to would be if you cared to keep the original engine original or wanted a 408. The block itself is fine for your intended power levels with forged goodies stuffed inside.
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Old Aug 29, 2025 | 09:20 AM
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Originally Posted by 98Redbird
I've got a 2004 Z06 with a Vortech Ti V3, TFS 220 heads and BTR Centri cam.

I'm wanting to explore going ahead and doing the shortblock so that I'm done with it, but am not sure if I should just utilize the shortblock that I already have and put a rotating assembly in it, or just buy a forged shortblock from one of the vendors?

It seems that I can save some money by just going with a rotating assembly and then having an engine shop somewhat local to me to do the machine work and put it together. I'm shooting for 800 or so rwhp out of the build.

What do you guys think? The factory shortblock only has about 9,000 miles on it, so it's in good shape.

Thanks!
I would definitely put that low mile gem on an engine stand, and build a nice LS3.
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Old Aug 29, 2025 | 09:57 AM
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Cash-wise, that low miles LS6 can probably be sold to make a few bucks towards any new engine if desired. Maybe an iron block for added peace of mind approaching 1k hp. Though the factory blocks are typically ok. Cranks too.

Having recently gone to about the 1k rw level and seen what that brings vs about 650, I can say it is a whole different beast up there and unless you've driven one you might want to see if someone you know is willing to toss you the keys to one for an afternoon before you commit to 800+. You either need a lot of long straight roads or the car becomes largely a track dedicated ride somewhere above 700rw.
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Old Aug 29, 2025 | 11:12 AM
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800 rear wheel is on the order of 940 crankshaft. The most I’ve ever had was around 450 RWHP
in a ‘68 Chevelle — the admonition of being aware of the difference strikes me as very wise.
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