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427 LSA build Help?!

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Old Aug 9, 2018 | 02:00 AM
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Thumbs up 427 LSA build Help?!

Hey guys have a few questions so I’m gonna explain what I got and my goals are and ask the questions at the end thanks guys.

427 4.125 bore LS block
10.5:1
91 cali/Meth
Ported LS3 heads
btr4 cam-ls7 specs pretty sure
Ported 1.9 LSA blower
stock gutted ls7 exhaust
custom 5 inch intake.
2.45 upper
lower is gonna be a 7.2 or a 8.0

goal is 700-800whp on blower at the end with full supporting mods so maybe headers and e85 down the road a 102 TB etc

how much boost will something like this make when does the lsa blower become a problem with rpms 24k??


going to use a stock zl1 HE with a interchiller I think down the road.


i will be using this blower for 1-2 years then swap for a Ported ls9 blower I’m not worried about sending the blower to get checked on every 10k miles can I overspin it safely really want this!!! Thanks guys ps I might be a little confusing bear with me
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Old Aug 12, 2018 | 08:35 AM
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23k rpm is the tipping point for the blower. Of course you can spin it faster but there is a point where it is unsafe & no longer efficient. Even at the max 23k rpm you will be fighting IAT & belt slip issues.
You can get to your goal but, you will need from the get go the full exhaust ( at least headers), E85, heat exchanger upgrade ( something like weaponX) & the proper pulley set up.
Ie: 2.5” upper & something like a 20% overdrive lower around 9”. The 2.45” standalone won’t get the boost you want & will be prone to belt slip.

Dont forget get all the supporting mods needed to carry this. ID1050 injectors (or bigger) along with a new fuel system. If I’m not mistaken the stock LSA ( zl1) pump handles mid 600 hp. Definitely needed is an upgrade or addition to the supercharger tensioner. Usually an additional idler pulley & bracket.

Attached is a graph to help with your pulley setup.
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Old Aug 12, 2018 | 09:11 AM
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I wouldn't use a BTR stage 4. So much overlap you'll just blow boost out the tailpipe.
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Old Aug 16, 2018 | 08:01 PM
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I would change the camshaft. Run a 2.45/9.1 pulley that’s a good safe pulley combo. Proper cooling mods are very important. More boost isn’t always better you want to have a good efficient motor combo that makes good power at moderate boost level (restriction). My ctsv makes 784whp at 12.8 psi thru a 6l90 and 1140whp on nitrous.
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Old Aug 17, 2018 | 06:33 AM
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Originally Posted by Dynospeed
I would change the camshaft. Run a 2.45/9.1 pulley that’s a good safe pulley combo. Proper cooling mods are very important. More boost isn’t always better you want to have a good efficient motor combo that makes good power at moderate boost level (restriction). My ctsv makes 784whp at 12.8 psi thru a 6l90 and 1140whp on nitrous.
Are you spraying a 300 shot?
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Old Aug 22, 2018 | 07:21 PM
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Originally Posted by NitrOmm

23k rpm is the tipping point for the blower. Of course you can spin it faster but there is a point where it is unsafe & no longer efficient. Even at the max 23k rpm you will be fighting IAT & belt slip issues.
You can get to your goal but, you will need from the get go the full exhaust ( at least headers), E85, heat exchanger upgrade ( something like weaponX) & the proper pulley set up.
Ie: 2.5” upper & something like a 20% overdrive lower around 9”. The 2.45” standalone won’t get the boost you want & will be prone to belt slip.

Dont forget get all the supporting mods needed to carry this. ID1050 injectors (or bigger) along with a new fuel system. If I’m not mistaken the stock LSA ( zl1) pump handles mid 600 hp. Definitely needed is an upgrade or addition to the supercharger tensioner. Usually an additional idler pulley & bracket.

Attached is a graph to help with your pulley setup.

sorry should of said it’s going in a c6 z06 so I’ll have to
use a pulley that fits that car so it doesn’t hit the steering rack. Is 750-800whp possible with a 427 Ls7 ported heads Big FI cam 2 inch headers and ported lsa 102 and a cai on e? 10.5:1 the heads would be with a ls3-ls7 adapter plate
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Old Aug 22, 2018 | 07:23 PM
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Originally Posted by ddnspider
Are you spraying a 300 shot?

how well are those stock trans I might come to a point of buyin a 60-70k mileish cts v want 700whp if I went that way stock trans can hold up? But that’s my last resort just curious
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Old Aug 22, 2018 | 07:25 PM
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Originally Posted by Dynospeed
I would change the camshaft. Run a 2.45/9.1 pulley that’s a good safe pulley combo. Proper cooling mods are very important. More boost isn’t always better you want to have a good efficient motor combo that makes good power at moderate boost level (restriction). My ctsv makes 784whp at 12.8 psi thru a 6l90 and 1140whp on nitrous.

i called weapon x and they said on a 427 and a LSA I could only get 650whp but then another one of there guys said I can damn sure hit 800whp
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