compression with lb9 and vortecs? - Hot Rod Forum : Hotrodders Bulletin Board
Hotrodders.com -- Hot Rod Forum



Register FAQ Search Today's Posts Unanswered Posts Auto Escrow Insurance Auto Loans
Hot Rod Forum : Hotrodders Bulletin Board > Tech Help> Engine
User Name
Password
lost password?   |   register now

Reply
 
LinkBack Thread Tools
  #1 (permalink)  
Old 01-27-2009, 09:44 PM
slate84's Avatar
Registered User
 
Last photo:
Join Date: Jan 2009
Location: brookings south dakota
Posts: 127
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
compression with lb9 and vortecs?

I'm running a 87 iroc 305, lt1 cam, with 906 vortec heads, i know that the 906's have larger chambers than the lb9's 58's, but is there a head gasket i could use so i don't have to mill the heads, but still keep a 9+/1 compression?

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 01-28-2009, 04:33 AM
Everything is HAMMER!
 
Last photo:
Join Date: Jan 2006
Location: belleville, Michigan
Age: 25
Posts: 348
Wiki Edits: 0

Thanks: 2
Thanked 1 Time in 1 Post
Trade those 906's for a set of rebuilt and ported 416's,they'll keep your compression up and they'll be more than you'll ever need to feed a street driven small block.
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 01-28-2009, 12:18 PM
slate84's Avatar
Registered User
 
Last photo:
Join Date: Jan 2009
Location: brookings south dakota
Posts: 127
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
i'd like to keep the 906's since they just got rebuilt and i plan on using these heads on the 350 bottom im building in the future.
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 01-28-2009, 12:29 PM
F-BIRD'88's Avatar
Yada Yada Yada
 
Last photo:
Join Date: Oct 2005
Location: Ontario, Canada
Posts: 9,153
Wiki Edits: 0

Thanks: 5
Thanked 380 Times in 374 Posts
Felpro #1094 .015" steel shim Head gasket.

The factory "LT1" hyd roller cam was intended for a engine with 10:1 cr.
You could advance it a bit to compensate for being a bit short on compression ratio and cubes..

Last edited by F-BIRD'88; 01-28-2009 at 12:38 PM.
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 01-28-2009, 05:26 PM
slate84's Avatar
Registered User
 
Last photo:
Join Date: Jan 2009
Location: brookings south dakota
Posts: 127
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
i've read in quite a few forums on 3rdgen.org that the lt1 cam was a good canidate for the lb9 motors. was i missinformed?
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 01-28-2009, 09:49 PM
F-BIRD'88's Avatar
Yada Yada Yada
 
Last photo:
Join Date: Oct 2005
Location: Ontario, Canada
Posts: 9,153
Wiki Edits: 0

Thanks: 5
Thanked 380 Times in 374 Posts
Quote:
Originally Posted by slate84
i've read in quite a few forums on 3rdgen.org that the lt1 cam was a good canidate for the lb9 motors. was i missinformed?
Its a cheap way to upgrade from the tini tiny stock LB9 cam.
But like any other cam it needs to be matched to the job. When you increase the cam valve open duration, the intake valve closing point is delayed. To recover the loss of physical compression, the mechanical compression ratio of said engine needs to be increased to restore the cylinder pressure.
Like I said the LT1 cam needs a higher than stock compression ratio.
The LT1 motor is 10:1. the LT4 motor is 10.4:1. Take that as a clue.
Cam timing is aways a compromise. You can fine tune the LT1 cam into your motor by adjusting the cam phasing. Closing the intake valve sooner (cam advanced) creates more low rpm cylinder pressure and torque.
A small Ci motor being short on torque to start with requires critical cam/valve event timing. It all has to work together. If you expect a new camshaft with more duration and or later intake valve closing point, than the old cam, to make more power, the heads have to flow more air and the mechanical compression ratio has to be higher (within limits). The usable rpm range is extended but usually at the cost of some low rpm torque. Needs more gear ratio and a higher stall torque converter. The cam/valve events must also work in sync with the exhaust system (scavegeing). If the exhaust is restrictive (stock puney manifolds/pipes) don;t expect much more power.
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 01-29-2009, 09:36 PM
Member
 
Last photo:
Join Date: May 2003
Location: Shreveport LA
Age: 64
Posts: 5,103
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
The LT1 motor also has a cooling system that is designed to cool the heads before the block, allowing a higher compression ratio to be used without detonating. A standard block-first cooling system will require less CR in order to avoid detonation problems.
Reply With Quote Quick reply to this message

Recent Engine posts with photos

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Hot Rod Forum : Hotrodders Bulletin Board forums, you must first register.
Please enter your desired user name (usually not your first and last name), your email address and other required details in the form below.
User Name:
If you do not want to register, fill this field only and the name will be used as user name for your post.
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On



All times are GMT -6. The time now is 08:09 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.