Opinion Requested: 418 vs 427
Thread Starter
Teching In
Joined: Jul 2005
Posts: 15
Likes: 2
From: Sunny Florida
Opinion Requested: 418 vs 427 Seems like the LS7 block has been discontinued at GM, joining the LS1, LS2, LS6, LS9 blocks. Seems like Gen III aluminum blocks are already gone and Gen IV aluminum blocks will soon be a lot harder to locate new. LS3 and LSA blocks are still around for now and certainly capable of allowing for some nice power. I'd love to build a LS7 engine and thinking of buying the block now before they're totally gone, although I've read a lot of differing opinions of the LS7 block: weak liners and other potential issues. Honestly, I'm a NA guy and looking for something around the 500-550whp range with decent street manners (not a track monster) and I figure the 427 would be better suited vs the stroked LS3. Any major issues with with the LS7 block? I see it's about $1500 more than the LS3 block and $1000 more than the LSA. Thoughts??
I’ve seen the LS7 sleeves crack way more often than any if the other LS blocks, so personally I would rather stroke an LS3 to 427ci (or more) over running an LS7 block with stock sleeves.
if you really want a 4.125” bore, I would suggest a TSP or RED sleeved block with aftermarket sleeves.
if you really want a 4.125” bore, I would suggest a TSP or RED sleeved block with aftermarket sleeves.
How many have you seen where the saddles had been torn away from the sides of the block? I've seen two from the same guy who used them on boosted applications. Not sure what caused it other than too much pressure from boost in the LS7 block with forged internals. I'm pretty sure it was a Manley crank he was using becasue it was for sale too but for an NA build the LS7 would be okay. Why not send a 5.3 aluminum to RED to be sleeved out to 4.155 and build a 434. Probably cost about the same as that LS7 block.
Banned
Joined: Oct 2020
Posts: 1,984
Likes: 682
How many have you seen where the saddles had been torn away from the sides of the block? I've seen two from the same guy who used them on boosted applications. Not sure what caused it other than too much pressure from boost in the LS7 block with forged internals. I'm pretty sure it was a Manley crank he was using becasue it was for sale too but for an NA build the LS7 would be okay. Why not send a 5.3 aluminum to RED to be sleeved out to 4.155 and build a 434. Probably cost about the same as that LS7 block.
But Dart Dart Dart best of the best👌
Everyone's selling sleeved blocks Mast also I think
Yeah I called RED today and they do not do LS1 blocks anymore and a re-sleeved aluminum 5.3 was going for $2400. It had to be the newer Gen IV aluminum blocks with the siamese bore GM 12571048. I have an aluminum 5.3 on an engine stand and I sure hope it's that one as I had plans for it.
Trending Topics
For 500 to 550, I'd keep is simple and just do the 416 on an LS3 block. 11.5:1, decent heads, low 230's cam, ported and rod modded stock LS3 intake manifold, and 2" long tubes should do it easily. Won't break the bank and should be a nice driver with any kind of decent tuna.
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
Gas Monkey Built a 6-Wheel Ferrari Testarossa With a Corvette LT4 Engine
Verdad Gallardo
7 Most Reliable High-Performance Engines GM Has Ever Built
Verdad Gallardo
Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin
Verdad Gallardo
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Building a 416 LS3/LSA to 500whp to 550whp with ported LS3 heads & ~237/245 and rod mod LS3 intake is a well proven recipe. Lot of ways to make a 427, for instance a 4.1 stroke crank in a 4.070 bore LS3/LSA block will do it. It its about making ~500whp to 550whp, I'd stick with the LS3 heads and LS3/LSA block. This a proven reliable combo of parts.
If it's about "cool", a NA LS7 427 is "cooler" than LS3/LSA 416 or 427 etc. Just be sure to have a well proven LS cylinder head shop do the LS7 heads as many have had valve guide wear issues according what's frequently posted on internet forums.
If it's about NA horsepower, reliability & future flexibility, big cubes definitely a sleeved 5.3/LS2/LS3 with a big 4.125 to 4.185 bore from Steve@RED as mentioned above. Maybe be even go 4.185 bore & 4.125 stroke for a 454!
If it's about "cool", a NA LS7 427 is "cooler" than LS3/LSA 416 or 427 etc. Just be sure to have a well proven LS cylinder head shop do the LS7 heads as many have had valve guide wear issues according what's frequently posted on internet forums.
If it's about NA horsepower, reliability & future flexibility, big cubes definitely a sleeved 5.3/LS2/LS3 with a big 4.125 to 4.185 bore from Steve@RED as mentioned above. Maybe be even go 4.185 bore & 4.125 stroke for a 454!
Originally Posted by 99 Black Bird T/A
Building a 416 LS3/LSA to 500whp to 550whp with ported LS3 heads & ~237/245 and rod mod LS3 intake is a well proven recipe. Lot of ways to make a 427, for instance a 4.1 stroke crank in a 4.070 bore LS3/LSA block will do it. It its about making ~500whp to 550whp, I'd stick with the LS3 heads and LS3/LSA block. This a proven reliable combo of parts.
If it's about "cool", a NA LS7 427 is "cooler" than LS3/LSA 416 or 427 etc. Just be sure to have a well proven LS cylinder head shop do the LS7 heads as many have had valve guide wear issues according what's frequently posted on internet forums.
If it's about NA horsepower, reliability & future flexibility, big cubes definitely a sleeved 5.3/LS2/LS3 with a big 4.125 to 4.185 bore from Steve@RED as mentioned above. Maybe be even go 4.185 bore & 4.125 stroke for a 454!
If it's about "cool", a NA LS7 427 is "cooler" than LS3/LSA 416 or 427 etc. Just be sure to have a well proven LS cylinder head shop do the LS7 heads as many have had valve guide wear issues according what's frequently posted on internet forums.
If it's about NA horsepower, reliability & future flexibility, big cubes definitely a sleeved 5.3/LS2/LS3 with a big 4.125 to 4.185 bore from Steve@RED as mentioned above. Maybe be even go 4.185 bore & 4.125 stroke for a 454!
Thread Starter
Teching In
Joined: Jul 2005
Posts: 15
Likes: 2
From: Sunny Florida
Thanks for the replies!!
Ideally, I wanted a Gen III block since it's easier (no adapters needed) to install in my C5, but that's not an easy option anymore...and apparently RED and/or others are not resleeving LS1/LS6 blocks. For about two seconds, I entertained the idea of getting a C5R block, but $9k for the block alone is ton of money for something that will live on the street with not a ton of HP. I was going to reach out to Mr Mamo for the heads and maybe he can also offer a suggestion on rest of build. I do like the results of those couple 434 builds that have been posted here
So many options...just gotta pick one and make it happen!!
Ideally, I wanted a Gen III block since it's easier (no adapters needed) to install in my C5, but that's not an easy option anymore...and apparently RED and/or others are not resleeving LS1/LS6 blocks. For about two seconds, I entertained the idea of getting a C5R block, but $9k for the block alone is ton of money for something that will live on the street with not a ton of HP. I was going to reach out to Mr Mamo for the heads and maybe he can also offer a suggestion on rest of build. I do like the results of those couple 434 builds that have been posted here
So many options...just gotta pick one and make it happen!! 
Thanks for the replies!!
Ideally, I wanted a Gen III block since it's easier (no adapters needed) to install in my C5, but that's not an easy option anymore...and apparently RED and/or others are not resleeving LS1/LS6 blocks. For about two seconds, I entertained the idea of getting a C5R block, but $9k for the block alone is ton of money for something that will live on the street with not a ton of HP. I was going to reach out to Mr Mamo for the heads and maybe he can also offer a suggestion on rest of build. I do like the results of those couple 434 builds that have been posted here So many options...just gotta pick one and make it happen!!
Ideally, I wanted a Gen III block since it's easier (no adapters needed) to install in my C5, but that's not an easy option anymore...and apparently RED and/or others are not resleeving LS1/LS6 blocks. For about two seconds, I entertained the idea of getting a C5R block, but $9k for the block alone is ton of money for something that will live on the street with not a ton of HP. I was going to reach out to Mr Mamo for the heads and maybe he can also offer a suggestion on rest of build. I do like the results of those couple 434 builds that have been posted here
So many options...just gotta pick one and make it happen!!LS1-machine-shop-questions - see post #15
There is no big problem using a Gen IV block to replace the Gen III in your car. LS2 LS3 or variants or 5.3 12571048 block will work. Scoggin can supply the needed pieces for the swap. I can re thread the knock sensor holes on the sides of the Gen IV block to receive the Gen III sensors. A dry sleeved block is much better for a street application regardless. No need for front and rear motor plates to support the block. Bore size range is 4.125" to 4.185" NA with 4.155" the max recommended for boost or nitrous. 434" would be 4.155" x 4" stroke. 454 would be 4.185" x 4.125" stroke. HPR builds 468" and larger engines using my dry sleeved blocks. If you are looking for something along those lines, contact Anthony at Horsepower Research.
__________________
Steve Demirjian
Race Engine Development
Oceanside, Ca.
760-630-0450
web: www.raceenginedevelopment.com/
e-mail: race-engine-development@***.net
Steve Demirjian
Race Engine Development
Oceanside, Ca.
760-630-0450
web: www.raceenginedevelopment.com/
e-mail: race-engine-development@***.net
Thanks for the replies!!
Ideally, I wanted a Gen III block since it's easier (no adapters needed) to install in my C5, but that's not an easy option anymore...and apparently RED and/or others are not resleeving LS1/LS6 blocks. For about two seconds, I entertained the idea of getting a C5R block, but $9k for the block alone is ton of money for something that will live on the street with not a ton of HP. I was going to reach out to Mr Mamo for the heads and maybe he can also offer a suggestion on rest of build. I do like the results of those couple 434 builds that have been posted here So many options...just gotta pick one and make it happen!!
Ideally, I wanted a Gen III block since it's easier (no adapters needed) to install in my C5, but that's not an easy option anymore...and apparently RED and/or others are not resleeving LS1/LS6 blocks. For about two seconds, I entertained the idea of getting a C5R block, but $9k for the block alone is ton of money for something that will live on the street with not a ton of HP. I was going to reach out to Mr Mamo for the heads and maybe he can also offer a suggestion on rest of build. I do like the results of those couple 434 builds that have been posted here
So many options...just gotta pick one and make it happen!!
There is no big problem using a Gen IV block to replace the Gen III in your car. LS2 LS3 or variants or 5.3 12571048 block will work. Scoggin can supply the needed pieces for the swap. I can re thread the knock sensor holes on the sides of the Gen IV block to receive the Gen III sensors. A dry sleeved block is much better for a street application regardless. No need for front and rear motor plates to support the block. Bore size range is 4.125" to 4.185" NA with 4.155" the max recommended for boost or nitrous. 434" would be 4.155" x 4" stroke. 454 would be 4.185" x 4.125" stroke. HPR builds 468" and larger engines using my dry sleeved blocks. If you are looking for something along those lines, contact Anthony at Horsepower Research.
That's twenty year old stuff where the only way to a large bore was with wet MID liners. Darton doesn't stock the sleeves any more. Dry liners in Gen IV and V blocks work great. Stock motor mount locations work. Less problematic and less costly.
__________________
Steve Demirjian
Race Engine Development
Oceanside, Ca.
760-630-0450
web: www.raceenginedevelopment.com/
e-mail: race-engine-development@***.net
Steve Demirjian
Race Engine Development
Oceanside, Ca.
760-630-0450
web: www.raceenginedevelopment.com/
e-mail: race-engine-development@***.net
On The Tree
Joined: Oct 2011
Posts: 127
Likes: 44
From: Colorado
The GM LS7 and LSA blocks have ~0.5" longer sleeves then LS3 blocks so the piston skirts have a bit more stability at BDC when going longer than the 3.622" stroke. The oil squirters on the LSA might need to be removed or reworked with a stroker crank; dunno know how LS7 oil squirters work with their longer stroke crank.