Boosted + High Compression
Thread Starter
Staging Lane
Joined: Jan 2011
Posts: 82
Likes: 0
From: Massachusetts
Boosted + High Compression What would you guys assume is safe to run out of a rear mount turbo on a forged bottom (383) end 2 bolt main lt1 with 11.1 compression? Same question for a d1sc? Eagle crank, h beam rods, mahle pistons. And what would you guys recommend for meth etc.
Oh dear god why do you guys build high compression big cammed engines then when you realize it's not fast enough you want to go boost? Should have built it right the first time.... mine is 9.3:1 or so and I don't have the supercharger yet and a modest cam (has a perfect defined lope at stock idle) and it is far from a dog on the street. In fact it's quite fun, very torquey!
You're going to have to swap out the heads or the pistons or both to drop your compression. Or you could just run nitrous. You could go with low boost and pull timing, but there is hardly a point to that. Oh, and another plus is that if you go supercharger then you really should double key your crank and get a stout damper/hub. With a turbo, you can go without, but you'll be in boost at lower rpm... (bad thing or good thing...)
You're going to have to swap out the heads or the pistons or both to drop your compression. Or you could just run nitrous. You could go with low boost and pull timing, but there is hardly a point to that. Oh, and another plus is that if you go supercharger then you really should double key your crank and get a stout damper/hub. With a turbo, you can go without, but you'll be in boost at lower rpm... (bad thing or good thing...)
Thread Starter
Staging Lane
Joined: Jan 2011
Posts: 82
Likes: 0
From: Massachusetts
Oh dear god why do you guys build high compression big cammed engines then when you realize it's not fast enough you want to go boost? Should have built it right the first time.... mine is 9.3:1 or so and I don't have the supercharger yet and a modest cam (has a perfect defined lope at stock idle) and it is far from a dog on the street. In fact it's quite fun, very torquey!
You're going to have to swap out the heads or the pistons or both to drop your compression. Or you could just run nitrous. You could go with low boost and pull timing, but there is hardly a point to that. Oh, and another plus is that if you go supercharger then you really should double key your crank and get a stout damper/hub. With a turbo, you can go without, but you'll be in boost at lower rpm... (bad thing or good thing...)
You're going to have to swap out the heads or the pistons or both to drop your compression. Or you could just run nitrous. You could go with low boost and pull timing, but there is hardly a point to that. Oh, and another plus is that if you go supercharger then you really should double key your crank and get a stout damper/hub. With a turbo, you can go without, but you'll be in boost at lower rpm... (bad thing or good thing...)
I always laugh at the people who regurgitate the same spoon-fed paup about high compression and boost. I have a gen 1 sbc 383 with 10.5 scr and 13# of intercooled boost from an old school p1200br and water/meth and it makes 800hp at the flywheel on 93 pump gas. I run 32* of timing, so don't beleive what everyone else says, now that being said Procharger and others that make setups for the LT1 design them to work with the stock scr of 10.5:1 and you don't have to change the pistons or heads to run it. It all depends on how much boost/rwhp you want to make but since your bottomend is all forged I would think you could get away with the same boost that the stock LT1 can run especially if you add a Snow Performance water/meth kit which is 8-9# of boost.
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I always laugh at the people who regurgitate the same spoon-fed paup about high compression and boost. I have a gen 1 sbc 383 with 10.5 scr and 13# of intercooled boost from an old school p1200br and water/meth and it makes 800hp at the flywheel on 93 pump gas. I run 32* of timing, so don't beleive what everyone else says, now that being said Procharger and others that make setups for the LT1 design them to work with the stock scr of 10.5:1 and you don't have to change the pistons or heads to run it. It all depends on how much boost/rwhp you want to make but since your bottomend is all forged I would think you could get away with the same boost that the stock LT1 can run especially if you add a Snow Performance water/meth kit which is 8-9# of boost.
http://www.hotrod.com/techarticles/h...g_bang_theory/
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Verdad Gallardo Well ahritchie lets see how much power your 4.8 LS would make with the same procharger or how much my setup would make with the same size turbo used in the 4.8 LS build? And what makes you think a fully forged 383 with 8-9# of intercooled boost couldn't last 200k with proper maintenence? So while you're talking out your *** do you personally own anything with forced induction, I thought not so what qualifies you to try and correct me?
Well ahritchie lets see how much power your 4.8 LS would make with the same procharger or how much my setup would make with the same size turbo used in the 4.8 LS build? And what makes you think a fully forged 383 with 8-9# of intercooled boost couldn't last 200k with proper maintenence? So while you're talking out your *** do you personally own anything with forced induction, I thought not so what qualifies you to try and correct me?
Lol you don't know me! Provide some valid examples of real world high compression (11:1) blown setups lasting 200K...l'm waiting. Not talking about "in theory". And actually, I just took ownership of a piece of true high performance blown American muscle...get ready...wait for it....1999 Buick Regal GS supercharged! 
My girlfriend gave the thing away because she's tired of the "grandma car"....I've been using it to keep the miles of my birds and the great MPG...Complete sleeper 
I'm strongly considering slapping a smaller pulley on that bitch, some headers, cai, and a tune and make 300+ front wheel HP in the grandma Buick. 
TECH Enthusiast
Joined: Jun 2002
Posts: 634
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From: In the garage fixing LT1
You don't even need new pistons to drop the compression. A thicker gasket or just a bowl and polish job on the heads can lower the compression enough. There are several ways to make a high compression engine live on boost, strong intercooling helps, rich tune among other options.
The reason any FI engine detonates is because the owners don't follow the tuning rules and push the limits too far.
The reason any FI engine detonates is because the owners don't follow the tuning rules and push the limits too far.
