415 with PRC 2.5 243s
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415 with PRC 2.5 243s The my c5z ate a lifter and ruined the block. I am considering building a 415 ls3 from a new ls3 block and reuse my PRC “stage 2.5” 243 heads with the fast 90 off my car. I realize this combination isn’t really ideal for peak power but I am incorrect in thinking this will be a good low end torque setup. Is there a more logical setup for roughly the same cost? I’ve had the C5Z for nearly 10 years and have no intention of getting rid of it. It’s used to rip around town, do a handful of autoxs a year, and an occasional track day.
Nope, no longer being casted.
You can still find new on the shelf, but this is drying up quick.
Obviously used stuff is still out there, but those are becoming scarcer every day too. Not to mention finding undamaged ones. A lot of crap gets pawned off to unsuspecting buyers.
You can still find new on the shelf, but this is drying up quick.
Obviously used stuff is still out there, but those are becoming scarcer every day too. Not to mention finding undamaged ones. A lot of crap gets pawned off to unsuspecting buyers.
Yep, even the used LS1 engines that are correctly built with great leak down numbers aren't going to last. If you see one listed, grab it. You never know when you may need it for a project.
I know where there is a Lingenfelter built LS1 with 26k miles on it with forged pistons that already has PRC “stage 2.5” heads on it.
I know where there is a Lingenfelter built LS1 with 26k miles on it with forged pistons that already has PRC “stage 2.5” heads on it.
The my c5z ate a lifter and ruined the block. I am considering building a 415 ls3 from a new ls3 block and reuse my PRC “stage 2.5” 243 heads with the fast 90 off my car. I realize this combination isn’t really ideal for peak power but I am incorrect in thinking this will be a good low end torque setup. Is there a more logical setup for roughly the same cost? I’ve had the C5Z for nearly 10 years and have no intention of getting rid of it. It’s used to rip around town, do a handful of autoxs a year, and an occasional track day.
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Verdad Gallardo That would probably be a bad investment as who knows what condition the molds are in. Several in the aftermarket are gearing up to make blocks, but all have been slow to the table. JMO, I think we are at least 2yrs out on any sort of alternative, affordable prod block replacement.
The LS3 crate engines are hard to locate (whomever still has them in stock). The only alternative would be a resleeved aluminum block or used LS3 block if you want to stick with aluminum. Summit Racing offers a pretty neat iron block if you're willing to take the weight penalty.
The PRC 2.5 243s would perform just fine on a stroker, not optimized but you know that already.
The PRC 2.5 243s would perform just fine on a stroker, not optimized but you know that already.
Manufacturing stopped in 2014. Lots and lots of leftover stock made it’s way into vehicles up until 2020. I bought a new 2500 savanah van in 2020 with an LS 6 liter in it. If there are any LS crates out there on shelves, they are few and far between.
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Joined: May 2008
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From: Carnation, WA
That kind of makes me think I should sit on the one that I’m soon going to have surplus. But that’s hoarder thinking… and I should know. My brother and I took 6 25 yard dumpsters of crap out of dad‘s house when we were cleaning it up. 🙂
Still tempting.
Still tempting.
Teching In
Joined: May 2025
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combo will work fine for your goals. A 415 with PRC 2.5 243s and a FAST 90 won’t be peak HP optimized, but it’ll make tons of low-end and midrange torque—perfect for street/autoX/occasional track.
If you’re set on reusing parts and keeping cost in check, it’s a solid plan. Only change I’d consider: maybe step up to a FAST 102 and matching TB down the line to un-choke it up top—but not urgent unless you’re chasing numbers.
Reliable, torquey, and fun—hard to argue with that setup for your C5Z use case.
If you’re set on reusing parts and keeping cost in check, it’s a solid plan. Only change I’d consider: maybe step up to a FAST 102 and matching TB down the line to un-choke it up top—but not urgent unless you’re chasing numbers.
Reliable, torquey, and fun—hard to argue with that setup for your C5Z use case.
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This was also when the housing market was absolutely bonkers and we sold the ******* house at the yard sale, which is why 1-800-GOT-JUNK was called at the end for a fast and final cleanout.
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Joined: May 2008
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From: Carnation, WA
Those are rookie numbers. When we were cleaning out my in-laws' house for downsizing, we had four 40-yard dumpsters, one 30-yard dumpster, a yard sale, and a final cleanup from 1-800-GOT-JUNK.
This was also when the housing market was absolutely bonkers and we sold the ******* house at the yard sale, which is why 1-800-GOT-JUNK was called at the end for a fast and final cleanout.
This was also when the housing market was absolutely bonkers and we sold the ******* house at the yard sale, which is why 1-800-GOT-JUNK was called at the end for a fast and final cleanout.
I have had to clean stuff out, but not like that. I did have a $10k garage sale in 1998 when my Grandmother passed. So many people came, the cops came and directed traffic in a residential culdesac.
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From: Wilmington, De