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6.0L LQ9/LQ4 317 Heads vs 243 Heads?

93K views 24 replies 16 participants last post by  05 IBM M6 
#1 ·
Looking at getting either 243 Heads or now I see these 317 Heads from an LQ9/LQ4 motor....what would be the difference?? Please help, searched but couldn't find anything real informational.
 
#3 ·
i believe the 317 heads have lower compressionm which is ideal for forced induction. Dont quote me though.
 
#4 ·
The 317 is a 243 but with a larger CC. I have the 317 on my car with 70CC
 
#19 ·
so if one were to go with a set of 317 heads, how much boost can you run with stock internals? im looking at getting a 2.7 in pulley.
 
#5 ·
This is off topic, but I have a question concerning the valve springs on the stock ls2 heads. Are the ls2 springs weaker than the ones on the 243 heads off the 02-04 z06? The Z06 ones are good to .570 lift I believe, wondering what the ls2 ones are, if they can support the Z06 camshaft. Also can you tell the difference between the springs on each of the heads, are they a different color or anything?
 
#10 ·
Thanks for the reply however my initial post had a typing error in it sorry, ive got an LS2 not LS3 so would need them to fit the LS2 and for FI reasons the originally mentioned heads are ideal for lowering the compression ratio so was looking at them but not sure if they will bolt onto the LS2 without mods?
 
#17 ·
The LQ9 is the 317 correct? If so yes the bolt on.
 
#22 ·
Keep pushing the boost up until the motor blows, then rebuild it exactly the same and lower boost 1psi.
 
#24 ·
i just ordered a 2.7 inch pulley. well see what happens. i did a little research on here, i think ill be okay
 
#25 ·
Im running a 2.6 on mine....and spinning the motor at 7500rpm....and its still running at
470rwhp
 
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