LS6 vs LM7 block differences?
LS6 vs LM7 block differences? I've read a bunch on this, and most answers are "same design but Iron" But the real question is, I know a 5.3L can be bore to the same max spec of 3.905 as an LS6, and all components, cam, crank, heads swap over...
But are there any block differences? I am most concerned about Oil galleys and passages...
The reason I ask...
I am currently rebuilding/repairing my LS6 in my road race car, turns out the block is trashed, Cylinder #8 is out of round and unable to be bored out(already at the max 3.905" bore. So I am in need of a block.
The iron block, although heavier(65-80lbs from what I've read) would give me more reliability and security.
But I am concerned about oiling in a 5.3L for a serious Road Race Application. It is not a max HP effort, only @ 380-400rwhp. But the car can/will pull 1.5-2g's at times, and oiling is my main concern.
Thoughts? Should I... 1. just find an Ls6 block replacement, or is a 5.3L up for the task? I found a full 5.3L motor for $50 delivered to my door, and having trouble even finding a decent used Ls6 block.
But are there any block differences? I am most concerned about Oil galleys and passages...
The reason I ask...
I am currently rebuilding/repairing my LS6 in my road race car, turns out the block is trashed, Cylinder #8 is out of round and unable to be bored out(already at the max 3.905" bore. So I am in need of a block.
The iron block, although heavier(65-80lbs from what I've read) would give me more reliability and security.
But I am concerned about oiling in a 5.3L for a serious Road Race Application. It is not a max HP effort, only @ 380-400rwhp. But the car can/will pull 1.5-2g's at times, and oiling is my main concern.
Thoughts? Should I... 1. just find an Ls6 block replacement, or is a 5.3L up for the task? I found a full 5.3L motor for $50 delivered to my door, and having trouble even finding a decent used Ls6 block.
I am pretty sure that the older design lm7 (up to 2003) is just like the ls1 as far as not having the bay to bay breather window that you are talking about...I think the newer 5.3s (not sure of engine code) have the ls6 style breathing capacity...
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TECH Fanatic
Joined: Jun 2011
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From: Katy, TX
my 2004 LM7 is like the top photo, but I don't really see an effective difference because here is a pic of the channel in the rear cover. Oil still flows by in both designs.
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[/IMG] Last edited by RezinTexas; Jan 26, 2012 at 05:47 PM.
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Yes I agree with the last post and if it is an older 5.3L then You can open up the passage in the rear cover very easily and quickly ,,,,,,,I did mine by hand with a 3/8" course round file in about 15 min .
