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HP check LS3 sleeved 427

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Old Mar 16, 2022 | 12:58 AM
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Default HP check LS3 sleeved 427

Having my LS3 416 mid sleeved for boost, taking it to 427. (4” crank, 4.125 bore). LS9 ported heads.

might wait a year before I add boost. Cam now w 416 is 630ish, 240 255 114 +14. Not sure what the next cam will be. If not the same I wouldn’t mind a little better idle (less vibrations at idle).

how much crank hp/tq do you think I’d get before boost? LS3 intake, 1 7/8 LT, 3” true dual no cats.

Thanks
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Old Mar 16, 2022 | 02:38 AM
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Originally Posted by Pbarby
Having my LS3 416 mid sleeved for boost, taking it to 427. (4” crank, 4.125 bore). LS9 ported heads.

might wait a year before I add boost. Cam now w 416 is 630ish, 240 255 114 +14. Not sure what the next cam will be. If not the same I wouldn’t mind a little better idle (less vibrations at idle).

how much crank hp/tq do you think I’d get before boost? LS3 intake, 1 7/8 LT, 3” true dual no cats.

Thanks
What's the compression?
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Old Mar 16, 2022 | 09:47 AM
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Originally Posted by Corona
What's the compression?
i knew I was missing something.

10.1:1 CR
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Old Mar 16, 2022 | 01:35 PM
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Originally Posted by Pbarby
Having my LS3 416 mid sleeved for boost, taking it to 427. (4” crank, 4.125 bore). LS9 ported heads.

might wait a year before I add boost. Cam now w 416 is 630ish, 240 255 114 +14. Not sure what the next cam will be. If not the same I wouldn’t mind a little better idle (less vibrations at idle).

how much crank hp/tq do you think I’d get before boost? LS3 intake, 1 7/8 LT, 3” true dual no cats.

Thanks
:
Cam Motion has a stroker, supercharger cam.......238*/254*, 119* LSA + 4*, 8* Overlap.

Check the link!


LS Hot Street Supercharged Stroker - Cam Motion

KW
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Old Mar 16, 2022 | 03:00 PM
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Originally Posted by KW Baraka
:
Cam Motion has a stroker, supercharger cam.......238*/254*, 119* LSA + 4*, 8* Overlap.

Check the link!


LS Hot Street Supercharged Stroker - Cam Motion

KW
that does sound promising. Likely a smoother idle than what I have now. If the motor can be driven with this cam and without a sc for a year or so, what crank power do you think The 427 would produce?
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Old Mar 18, 2022 | 10:28 AM
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Originally Posted by Pbarby
that does sound promising. Likely a smoother idle than what I have now. If the motor can be driven with this cam and without a sc for a year or so, what crank power do you think The 427 would produce?
I would guess 620+hp@crank.......
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Old Mar 19, 2022 | 12:39 AM
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Originally Posted by grinder11
I would guess 620+hp@crank.......
I'm thinking just short of 600hp @ the crank. That 119* LSA gonna flatten the power curve....

KW
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Old Mar 19, 2022 | 10:18 AM
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Originally Posted by KW Baraka
I'm thinking just short of 600hp @ the crank. That 119* LSA gonna flatten the power curve....

KW
Usually a wide LSA permits better higher rpm power, but falls quickly after peak, and gives up a lot under the curve.......
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Old Apr 18, 2022 | 12:52 AM
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Originally Posted by grinder11
Usually a wide LSA permits better higher rpm power, but falls quickly after peak, and gives up a lot under the curve.......
Thanks everyone. ~600 crank hp w blower cam above, sounds good.

How much boost could I safely add w pump gas? Can I get to 9-950 crank on 93?
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Old Apr 18, 2022 | 07:22 AM
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Boost-compression-ratio-chart may help with getting a rough idea of how much boost with various amounts of compression.
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Old Apr 18, 2022 | 03:32 PM
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Originally Posted by 99 Black Bird T/A
Boost-compression-ratio-chart may help with getting a rough idea of how much boost with various amounts of compression.
thank bb. Seems ultra conservative when reading other boosted posts. I’ve inquired with the engine builder to settle my thoughts/concerns/nerves.

Going for ~750-850rwhp and good street manors on 93 w room for more boost (of course).
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Old Apr 23, 2022 | 12:22 PM
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Originally Posted by Pbarby
Thanks everyone. ~600 crank hp w blower cam above, sounds good.

How much boost could I safely add w pump gas? Can I get to 9-950 crank on 93?
Not trying to rain on your parade, but if you're only going from a 416 to a 427, there's not much gain there for the investment required. You're adding only a bit over 1 cubic inch per cylinder, 1.375 to be exact. Maybe I'm missing something here. But if I'm not, why not go with a 441? You're probably keeping the crank you have now, right? That would save $$ for sure, but the 1.375 cubic inches per hole gain doesn't seem worthwhile, IMHO........
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Old Apr 24, 2022 | 10:49 PM
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Originally Posted by grinder11
Not trying to rain on your parade, but if you're only going from a 416 to a 427, there's not much gain there for the investment required. You're adding only a bit over 1 cubic inch per cylinder, 1.375 to be exact. Maybe I'm missing something here. But if I'm not, why not go with a 441? You're probably keeping the crank you have now, right? That would save $$ for sure, but the 1.375 cubic inches per hole gain doesn't seem worthwhile, IMHO........
great question, I don’t have a sensible answer. When I bought the 416 it was gapped for 150 shot w 11.1:1cr. I really wanted a sleeved 427 back then, but was trying to save a few grand. Over time, I liked the idea of boost more over n2o.

So,… going into the motor anyway for dished pistons to lower cr and gap rings. Keeping crank/rods.

Adding mid sleeves for longevity (hopefully), potential future boost increases, reduce piston rock and will still have a few rebuilds/bore if/when something happens…and I can call it a 427.

Last edited by Pbarby; Apr 24, 2022 at 11:01 PM.
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Old Apr 25, 2022 | 08:12 AM
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The mid sleeve is a wet sleeve isn’t it?
if that’s correct you will have to use motor plates , if you don’t youlll end up popping head gaskets with the block twisting
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Old Apr 25, 2022 | 10:56 AM
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Originally Posted by Mickyinks
The mid sleeve is a wet sleeve isn’t it?
if that’s correct you will have to use motor plates , if you don’t youlll end up popping head gaskets with the block twisting
Dry sleeve, it’s a LS3 (gen4, vs gen3 block).
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Old Apr 25, 2022 | 12:49 PM
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Originally Posted by Mickyinks
The mid sleeve is a wet sleeve isn’t it?
if that’s correct you will have to use motor plates , if you don’t youlll end up popping head gaskets with the block twisting
Not sure what is meant by 'motor plates', but I had a Darton LS1 MID 427 done by Steve@RED, and I didn't have 'motor plates', and never popped a head gasket. Just sayin'.......
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Old Apr 25, 2022 | 12:57 PM
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The Darton mid sleeve is by definition a wet sleeve…. Unless they have a dry sleeve called a mid also



I used the darton mid sleeve in my original block… without the motor plates it was twisting the block and not sealing heads properly… was told i had to use motor plates to stop it from twisting


https://www.enginelabs.com/news/making-your-stock-block-better-with-darton-mid-sleeves/

Last edited by Mickyinks; Apr 25, 2022 at 01:05 PM.
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Old Apr 29, 2022 | 11:32 PM
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The LS1 was a stronger base for MID. Solid main bearing bulkheads and head bolt holes extending to the crankcase. The long head bolts are the answer as they are on the Coyote blocks. That's why you were good to go. It's a moot point now since I'm not doing the MID on the LS any longer and Darton doesn't have the sleeves. There is no reason to go to the expense of MID when a dry sleeved Gen IV is plenty good enough for most applications and less problematic with coolants and so on. For really high horsepower builds a Dart block is the solution. I'm a Dart dealer for that reason.
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