Opinion Requested: 454 vs 427
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12 Second Club
Joined: Dec 2017
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From: San Antonio
Opinion Requested: 454 vs 427 This is similar to another thread going on in here, but I didn't want to high-jack that one. I was wondering if a set of ported LS3 heads and stock LS3 intake could provide enough air flow for a 454 CID engine. Let's say your power goal is 600+ hp at the crank, and you want to use LS3 heads and intake (for budget reasons). Would there be any benefit to building a 454 vs a 427? The parts cost difference is about $200-$300. In this hypothetical situation, I would be using my LS1 for this build, so the machine work is exactly the same cost.
I'm thinking that the heads and intake would limit the amount of power that either engine could make. I'm pretty sure either engine would make close to 700hp with good heads/intake. Assuming the heads can only support enough air flow for 600hp, does CID really matter? Would both engines make the same hp if that's all that the heads/intake could support?
I'm thinking that the heads and intake would limit the amount of power that either engine could make. I'm pretty sure either engine would make close to 700hp with good heads/intake. Assuming the heads can only support enough air flow for 600hp, does CID really matter? Would both engines make the same hp if that's all that the heads/intake could support?
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Joined: Dec 2017
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From: San Antonio
I like low end torque, and I would prefer to shift around 6500 rpms. I just wasn't sure if anything would change between a 427 and 454 if the air flow was limited. I like the idea of "old school" CID in an LS motor. I'm sure a 427 would make plenty of hp for me, but there are lots of LS 427s out there. I don't hear of LS 454s very often. It would be nice to have something different.
Is it possible to use an LS1 block to build a 427 or 454 nowadays?
To be reliable with a big bore LS1/LS6 blocks need the Darton MID wet interlocking sleeves which Steve at RED designed but the Darton MID wet interlocking sleeves aren't available anymore.
Upgrading to an LS7 or LS2/LS3/Gen IV 5.3 block and dry sleeving block will be required. One can make a 427 with a 4.070 LS3 block and long stroke.
441 w/LS3 heads plus LS7 block or sleeved Gen IV block with 4.125 bore & 4.125 stroke crank is probably the sweet spot. That should allow a refresh with an LS7 block and ideally several refreshes with a sleeved Gen IV LS2/LS3/5.3 that can go 4.185 bore.
454 if the extra refreshes aren't that important, take the sleeved Gen IV LS2/LS3/5.3 to 4.185 bore on the initial build.
To be reliable with a big bore LS1/LS6 blocks need the Darton MID wet interlocking sleeves which Steve at RED designed but the Darton MID wet interlocking sleeves aren't available anymore.
Upgrading to an LS7 or LS2/LS3/Gen IV 5.3 block and dry sleeving block will be required. One can make a 427 with a 4.070 LS3 block and long stroke.
441 w/LS3 heads plus LS7 block or sleeved Gen IV block with 4.125 bore & 4.125 stroke crank is probably the sweet spot. That should allow a refresh with an LS7 block and ideally several refreshes with a sleeved Gen IV LS2/LS3/5.3 that can go 4.185 bore.
454 if the extra refreshes aren't that important, take the sleeved Gen IV LS2/LS3/5.3 to 4.185 bore on the initial build.
Last edited by 99 Black Bird T/A; Apr 18, 2022 at 07:16 AM.
TECH Resident
Joined: Sep 2019
Posts: 819
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From: Melbourne, Australia
I started with ported ls3 heads and intake , 239/254 hydraulic cam. On my lsx454 549rwhp
Changed to Mamo tfs 260 ls7 heads , mamo ported msd intake, solid roller, 255/269 cam 680rwhp
I’ve done approx 30,000 miles on bottom end
Changed to Mamo tfs 260 ls7 heads , mamo ported msd intake, solid roller, 255/269 cam 680rwhp
I’ve done approx 30,000 miles on bottom end
This is similar to another thread going on in here, but I didn't want to high-jack that one. I was wondering if a set of ported LS3 heads and stock LS3 intake could provide enough air flow for a 454 CID engine. Let's say your power goal is 600+ hp at the crank, and you want to use LS3 heads and intake (for budget reasons). Would there be any benefit to building a 454 vs a 427? The parts cost difference is about $200-$300. In this hypothetical situation, I would be using my LS1 for this build, so the machine work is exactly the same cost.
I'm thinking that the heads and intake would limit the amount of power that either engine could make. I'm pretty sure either engine would make close to 700hp with good heads/intake. Assuming the heads can only support enough air flow for 600hp, does CID really matter? Would both engines make the same hp if that's all that the heads/intake could support?
I'm thinking that the heads and intake would limit the amount of power that either engine could make. I'm pretty sure either engine would make close to 700hp with good heads/intake. Assuming the heads can only support enough air flow for 600hp, does CID really matter? Would both engines make the same hp if that's all that the heads/intake could support?
Staging Lane
Joined: May 2017
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By the time you do all that machine work sleaving along with everything else and buying a stroker rotating assembly wouldn't be easier to buy an LSX454 bare block(which is machined and ready to go but of course double checking) and an LSX454 rotating assembly which comes forged? Block about $3500 and rotating assembly about $3500.00...Appr. 7k. all from GM. 454 block has a bigger bore than what you can get out of s 427 and a shorter stroke.
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Verdad Gallardo Thread Starter
12 Second Club
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From: San Antonio
By the time you do all that machine work sleaving along with everything else and buying a stroker rotating assembly wouldn't be easier to buy an LSX454 bare block(which is machined and ready to go but of course double checking) and an LSX454 rotating assembly which comes forged? Block about $3500 and rotating assembly about $3500.00...Appr. 7k. all from GM. 454 block has a bigger bore than what you can get out of s 427 and a shorter stroke.
I can get a rotating assembly for under $2k. The re-sleeving is about $2500. Heads are about $500. I figured I'd have about $6k in it by the time I'm done. With my LS1 block, I wouldn't have to worry about converting wiring or sensors. Everything would just bolt right back in. This would be a future build. I don't plan on building an engine for my Camaro anytime real soon. I want to build a shop/garage where I can do this first.
Ult - if the top ends are identical it will make similar power on either power plant. The 454 will make more torque, likely make peak power at slightly lower rpm, and drive nicer all
Things being equal.
Things being equal.
If you go 454 make sure you get good pistons with a good side load characteristics as the long 4.125 stroke makes the piston pop out the bottom of the sleeve even on a 5.8 inch sleeve. This causes piston rocking and will make the bore wear (say .003) and make the second ring turn and become ineffective oil scraper/seal and you will begin to burn oil. This may take 20,000-40,000 miles. Also whoever is assembling engine will want better rings to help accommodate this issue. They have come a long way with the strokers but rotating assembly may run you more than $2K if you want it done right just look what the guys at HPR charge.
I agree with you. The 454 will probably also make more power and torque under the curve. 
the 454 will do everything the 427 does but better. why it will make more under the curve, cammed correctly it will make more power up top also. 27 ci at only 1.5 hp per inch is still 40 hp.
Thread Starter
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From: San Antonio
Because I would have to buy a 5.3L.The aluminum blocks are not cheap, even in a 5.3L. I already have an LS1. Also, a 454 is bigger than a 434. After looking at some different combinations, I think a 440 would be more ideal for me. It still has the big 4.185 bore, but a shorter (4.0") stroke. The shorter stroke seems more reliable and wouldn't cause as many clearance issues. IDK. Either way, it would be awesome!
Because I would have to buy a 5.3L.The aluminum blocks are not cheap, even in a 5.3L. I already have an LS1. Also, a 454 is bigger than a 434. After looking at some different combinations, I think a 440 would be more ideal for me. It still has the big 4.185 bore, but a shorter (4.0") stroke. The shorter stroke seems more reliable and wouldn't cause as many clearance issues. IDK. Either way, it would be awesome!
Thread Starter
12 Second Club
Joined: Dec 2017
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From: San Antonio
I already talked to someone locally that can re-sleeve my LS1. Based on the price, I think it was for dry sleeves. Of course, I'll confirm everything before I take the LS1 apart. For now, I need to finish building the LMG I have been milking. 
You should contact Steve @ RED before you do this, just for questions. He’s been sleeving blocks for 50Ish years and can explain why the LS1 can’t be dry sleeved.
Totally agree!!! Dry sleeves are one thing. But MID sleeves are something else entirely! Not enough emphasis can be put on the skill level required to do this. You can ruin an engine block before you even get a chance to assemble it!!!