Are these heads identical??
09-20-2009, 07:23 PM
#1
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Are these heads identical?? I have been gathering information on here for quite some time, for my LQ9, but I have a few questions I couldn't get clear answers to.
I am familar with the specs on the 243 heads. Are these heads identical to the 243s...12576063 (bare head 1256485) link...http://speed-eng.com/store/ls2-cylin...7ceb769af1874f
The information I have seen shows a 70cc exhaust port while the 243s are 75cc. Also, the 243 combustion chamber is slightly (.45) smaller. I have some infromation on the 243 flow numbers...does anyone know the flow specs of these other heads.
Is it true that either of these heads can be used on my LQ9? My concern was that the 243s were originally on the 5.7?
I have a small .531 lift cam that I will be using and would like to upgrade from my 317 heads. I may be able to get a bare casting of either part number. Can I use the valves and rockers from my stock 317 heads along with (yellow) Z06 springs (12499224)? The valves on either set of heads are listed as being the same size as the 317s.
I am familar with the specs on the 243 heads. Are these heads identical to the 243s...12576063 (bare head 1256485) link...http://speed-eng.com/store/ls2-cylin...7ceb769af1874f
The information I have seen shows a 70cc exhaust port while the 243s are 75cc. Also, the 243 combustion chamber is slightly (.45) smaller. I have some infromation on the 243 flow numbers...does anyone know the flow specs of these other heads.
Is it true that either of these heads can be used on my LQ9? My concern was that the 243s were originally on the 5.7?
I have a small .531 lift cam that I will be using and would like to upgrade from my 317 heads. I may be able to get a bare casting of either part number. Can I use the valves and rockers from my stock 317 heads along with (yellow) Z06 springs (12499224)? The valves on either set of heads are listed as being the same size as the 317s.
09-20-2009, 07:27 PM
#2
same intake and exhaust port, but 317 has 71cc chamber
243 has 65cc chamber not 75
flow the same, same valves. i have 243 on a 4.060 bore. 243 come on vehicles with 3.78,3.9, and 4.0 bores. so there is no concern on using on a 6.0 engine. the ls2 is 4.00 engine and came with those heads, so did the 5.7 ls6 and even the 5.3's came with 243 heads from factory
243 has 65cc chamber not 75
flow the same, same valves. i have 243 on a 4.060 bore. 243 come on vehicles with 3.78,3.9, and 4.0 bores. so there is no concern on using on a 6.0 engine. the ls2 is 4.00 engine and came with those heads, so did the 5.7 ls6 and even the 5.3's came with 243 heads from factory
09-20-2009, 07:33 PM
#3
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The other heads (not the 317s) are listed as being from the LS2. Are they the same as the 243s but with a different part/casting number?? The specs are virtually the same except the 243s have a slightly smaller combustion chamber (about .5cc) and the exhaust port of the 243s is listed as 75cc while the LS2 head is listed as 70cc. I have not seen any flow data on the LS2 head but have some for the 243s.
09-20-2009, 08:46 PM
#5
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The info I seen shows that 317 and 243 heads have different flow rates...
http://www.theturboforums.com/smf/in...=122987.0;wap2 (edit)
I wanted to put the 243 heads on my LQ9 but 11 to 1 (CR) seems like a bit of overkill for a "driver" car.
How much can I change the CR with thicker gasket?? I am not familar with "quench" and the effect it has on spark knock but have heard that you can't just throw a thicker gasket on expect it to magically fix everything. Any help and guidance is appreciated.
http://www.theturboforums.com/smf/in...=122987.0;wap2 (edit)
I wanted to put the 243 heads on my LQ9 but 11 to 1 (CR) seems like a bit of overkill for a "driver" car.
How much can I change the CR with thicker gasket?? I am not familar with "quench" and the effect it has on spark knock but have heard that you can't just throw a thicker gasket on expect it to magically fix everything. Any help and guidance is appreciated.
Last edited by Paul57; 09-20-2009 at 09:39 PM. Reason: wrong link
09-20-2009, 09:38 PM
#6
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