Stroking/Boring 5.3L (LM7)
03-31-2008, 05:36 AM
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Stroking/Boring 5.3L (LM7) Hi Guys,
Done a search and there is a similar thread to this but no definitive answer. How much can you bore/stroke this block LM7. it was mentioned that you can bore it .125 to 3.905. Has anyone done this and is this safe.
The block is fully balanced. Attaching to the block will be the top of my current LS1 :LS1 heads, fast 90/90, 232/234/112 comp cam, ud pulley, 1 7/8 headers & twin 3 inch exhaust, hardened pushrods + all the usual bolt ons, built auto and 4200 stall.
My current LS1 is getting tired and my mechanic wants to try something different (different in Australia at least) to see if we can get more out of my current combo. Best so far is 365rwhp with standard LS1.
It is in a 2002 HSV II Clubsport
Cheers
Darren
Done a search and there is a similar thread to this but no definitive answer. How much can you bore/stroke this block LM7. it was mentioned that you can bore it .125 to 3.905. Has anyone done this and is this safe.
The block is fully balanced. Attaching to the block will be the top of my current LS1 :LS1 heads, fast 90/90, 232/234/112 comp cam, ud pulley, 1 7/8 headers & twin 3 inch exhaust, hardened pushrods + all the usual bolt ons, built auto and 4200 stall.
My current LS1 is getting tired and my mechanic wants to try something different (different in Australia at least) to see if we can get more out of my current combo. Best so far is 365rwhp with standard LS1.
It is in a 2002 HSV II Clubsport
Cheers
Darren
Last edited by VXCLUB; 04-02-2008 at 01:00 AM.
12-16-2008, 11:30 PM
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I know this is old but did you find any answers? from my research the LM7 can be bored to a 5.7L like the LS1 but you need the 3.6225 crank which I believe comes in the motor...correct me if im wrong
12-17-2008, 12:54 AM
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Know ahead of time that the cost of machine work and new pistons will be twice as expensive as buying a 6.0L. Only build the iron block 5.7L if you have something to prove, otherwise there's better power to be had with the 6.0L for a starting platform.
Originally Posted by ZMONSTER!
or go 4 inch crank and have a 383.
By the way, not all 5.3L's can go to 3.905. I have one in the trash and one at minimum wall thickness to prove it. When boring over the typical amount, ALWAYS SONIC TEST YOUR BLOCK.
12-17-2008, 01:04 AM
#5
Without a doubt. You can make a 5.3L into an iron block LS1 by boring it over. The 5.3L has everything you need, just buy the bigger pistons.
Know ahead of time that the cost of machine work and new pistons will be twice as expensive as buying a 6.0L. Only build the iron block 5.7L if you have something to prove, otherwise there's better power to be had with the 6.0L for a starting platform.
Or sell the 5.3L, don't spend money on sonic testing the block and having new pistons installed and rotating assembly balance, but instead buy a 6.0L and purchase a pre-balanced 408 rotating assembly.
By the way, not all 5.3L's can go to 3.905. I have one in the trash and one at minimum wall thickness to prove it. When boring over the typical amount, ALWAYS SONIC TEST YOUR BLOCK.
Know ahead of time that the cost of machine work and new pistons will be twice as expensive as buying a 6.0L. Only build the iron block 5.7L if you have something to prove, otherwise there's better power to be had with the 6.0L for a starting platform.
Or sell the 5.3L, don't spend money on sonic testing the block and having new pistons installed and rotating assembly balance, but instead buy a 6.0L and purchase a pre-balanced 408 rotating assembly.
By the way, not all 5.3L's can go to 3.905. I have one in the trash and one at minimum wall thickness to prove it. When boring over the typical amount, ALWAYS SONIC TEST YOUR BLOCK.
12-17-2008, 01:22 AM
#7
Do you have the casting number or know what casting logo was on the block??? Here is a thread I started when I was trying to find the difference in the block castings. I have to see if I still have the pictures of the blocks casting Logos. I know there was an early Version of the 4.8/5.3 L blocks that has a large 6.0 cast on top of it and it can be borred to 4.00 but I dont have a casting number or any good pictures of it ,only whats in the new books and what Jason from LPE told me.
http://www.performancetrucks.net/for...d.php?t=419881
http://www.performancetrucks.net/for...d.php?t=419881
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12-17-2008, 06:46 AM
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why not get a complete ls3 crate.... you will spend alot of money boring, stroking, balancing etc.. and still note have the same potential as a 4+ inch bore ls... unless your 5.3 needs boring anyway i dont think its cost effective...
i mean is you really like iron, then you would be better off with a 6.0...
i mean is you really like iron, then you would be better off with a 6.0...
