Boost with High Compression
Thread Starter
Joined: Nov 2001
Posts: 3,066
Likes: 0
From: Sunny San Diego
Boost with High Compression I have been running Stage II 5.3L heads for a while. And have been researching a Procharger. Could I get away with running any amount of boost?
depends on your cylinder pressure. what hp are you making right now with those heads? if under 500hp id think you have that much room to grow..
it would certainly be more cost effective to sell your current heads and put a set of stock 6.0's on and then the boost. you will be able to make just as much power.
it would certainly be more cost effective to sell your current heads and put a set of stock 6.0's on and then the boost. you will be able to make just as much power.
Thread Starter
Joined: Nov 2001
Posts: 3,066
Likes: 0
From: Sunny San Diego
I didn't really want to deal with swapping heads. But I know FI likes lower CR.
I am only @ 360 rwhp. I would like to get about 450 rwhp on FI. And maybe let N20 take me the rest of the way to 500.
I am only @ 360 rwhp. I would like to get about 450 rwhp on FI. And maybe let N20 take me the rest of the way to 500.
TECH Senior Member
Joined: Nov 2001
Posts: 11,603
Likes: 0
From: Chi-Town, IL
I think its playing with fire.....
I had some MTI stage 2 heads that were milled to 10.6:1 compression.....I was running 6psi, stock motor, with a 214/218 .540/.550 114lsa cam.....
I blew the head gasket on #7 w/this setup on pump gas......
I then changed the heads to TEA S2 5.7L 73cc chambers to lower comp to around 9.3:1, I was then seeing 4psi total, making around 460rwhp through the TH400....my motor was hurt I think from the head gasket deal, it dripped oil out of the breather valves
I had some MTI stage 2 heads that were milled to 10.6:1 compression.....I was running 6psi, stock motor, with a 214/218 .540/.550 114lsa cam.....
I blew the head gasket on #7 w/this setup on pump gas......
I then changed the heads to TEA S2 5.7L 73cc chambers to lower comp to around 9.3:1, I was then seeing 4psi total, making around 460rwhp through the TH400....my motor was hurt I think from the head gasket deal, it dripped oil out of the breather valves
Trending Topics
Thread Starter
Joined: Nov 2001
Posts: 3,066
Likes: 0
From: Sunny San Diego
Thanks for the info guys. I went ahead and also called ATI.
They say I shouldn't have a problem with running 4-5 psi on 11:1 CR. Just so long I don't have any detonantion.
In fact, they told me its not the boost or CR which is the problem. Its detonation. Just so long there is enough fuel to support the power. Truth?
Oh and anything under 5 psi with the P-1SC-1 is CARB legal. 
They say I shouldn't have a problem with running 4-5 psi on 11:1 CR. Just so long I don't have any detonantion.
In fact, they told me its not the boost or CR which is the problem. Its detonation. Just so long there is enough fuel to support the power. Truth?
Oh and anything under 5 psi with the P-1SC-1 is CARB legal.
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
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
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo
Originally Posted by Ed LS1 Vert
Thanks for the info guys. I went ahead and also called ATI.
They say I shouldn't have a problem with running 4-5 psi on 11:1 CR. Just so long I don't have any detonantion.
In fact, they told me its not the boost or CR which is the problem. Its detonation. Just so long there is enough fuel to support the power. Truth?
Oh and anything under 5 psi with the P-1SC-1 is CARB legal.
They say I shouldn't have a problem with running 4-5 psi on 11:1 CR. Just so long I don't have any detonantion.
In fact, they told me its not the boost or CR which is the problem. Its detonation. Just so long there is enough fuel to support the power. Truth?
Oh and anything under 5 psi with the P-1SC-1 is CARB legal.
Teching In
Joined: Feb 2004
Posts: 19
Likes: 0
Originally Posted by Ed LS1 Vert
In fact, they told me its not the boost or CR which is the problem. Its detonation. Just so long there is enough fuel to support the power. Truth?
Thread Starter
Joined: Nov 2001
Posts: 3,066
Likes: 0
From: Sunny San Diego
Originally Posted by A DEE O
Everone is trying to tell you something here! Sure ATI wii tell you its ok. Take advice from the guys here that have gone through this ****. It gets very expensive and alot of downtime. You will hate your car for a while, think about selling it, and then wonder why you didn't take what we said seriously. Your choice, just my 02. Angelo
Guess I will have to plan on switching them out. Should stock heads get me where I want to be?
Registered User
Joined: Jun 2002
Posts: 453
Likes: 0
From: Forced Induction Heaven
Don't mess with High CR and Boost...its not worth it. I blew up my motor running 10lbs of boost with an ATI Procharger, and I know a lot of people that have lost their motors 10-10.5:1 CR later on with 6-8lbs of boost. The stock PCM just can't keep the AFR perfect all the time..and it usually only takes once or twice with stock Hyperutetic Pistons...the Ring Lans crack like wafer crackers in big chunks....don't screw with it dude...a daily driver is not a daily driver with a blown motor...it becomes a project...listen to those that have blazed the path before you....I wouldn't listen to ATI for anything when it comes to the design of their LSx kits...they make good head units though.
Registered User
Joined: Jun 2002
Posts: 453
Likes: 0
From: Forced Induction Heaven
Its a no brainer than dude. Sell the 5.3liter heads and send your stock heads to Richard at WCCH. Have them opened up to 73cc's and have him install in a set of REV 1116 Valve Springs you will need them for a boosted motor. You will be able to run 10lbs of boost all day. It won't cost you an arm and a leg to have the chambers opened up either.
Thread Starter
Joined: Nov 2001
Posts: 3,066
Likes: 0
From: Sunny San Diego
According to ATI, to stay smog legal I need to stay under 5#. Can I be @ 450 rwhp with 5# and stock heads? Guess I could always switch to the 7# pulley. Then back to the 5# at smog time. As to how they know its beyond me.
I plan on dual springs to handle to cam. Any reason to get larger valves with FI?
Thanks again.
I plan on dual springs to handle to cam. Any reason to get larger valves with FI?
Thanks again.
Registered User
Joined: Jun 2002
Posts: 453
Likes: 0
From: Forced Induction Heaven
ATI is full of ****...the only thing you really need if they check is the CARB #...which is on there P1, but I have heard that they are seeking one for the D1...although..the P1 and the D1 look very similar if you get my drift.
For what it is worth..force induction does not rely on big cams and fully ported heads as much as NA.
I made 610/545 rwhp/rwtq @6200 rpms (I ran out of injector or fuel pump) using non ported LS6 heads (changed the valve springs only) and a Comp Xer 224 Cam. I think you just need to have your stock heads chambers opened up and some valve springs. You can probably make 450rwhp with 5-6lbs of boost because you will be able to make up for the CR drop with timing.
For what it is worth..force induction does not rely on big cams and fully ported heads as much as NA.
I made 610/545 rwhp/rwtq @6200 rpms (I ran out of injector or fuel pump) using non ported LS6 heads (changed the valve springs only) and a Comp Xer 224 Cam. I think you just need to have your stock heads chambers opened up and some valve springs. You can probably make 450rwhp with 5-6lbs of boost because you will be able to make up for the CR drop with timing.
Thread Starter
Joined: Nov 2001
Posts: 3,066
Likes: 0
From: Sunny San Diego
Thanks, you guys talked me into it. I'll take those stock heads, throw on dual-springs, Ti retainers. And get them on the engine. Then I should be able to run 5# or 7#
I may have a buyer on my heads already.
Hope I am not disappointed, since I have already run N20.
I may have a buyer on my heads already.
Hope I am not disappointed, since I have already run N20.
Last edited by Ed LS1 Vert; Apr 22, 2004 at 06:50 PM.
Thread Starter
Joined: Nov 2001
Posts: 3,066
Likes: 0
From: Sunny San Diego
Originally Posted by Shinobi'sZ
ATI is full of ****...the only thing you really need if they check is the CARB #...which is on there P1, but I have heard that they are seeking one for the D1...although..the P1 and the D1 look very similar if you get my drift.
Can anyone verify if the 5# or the 7# has a CARB # on it?