milling AFR
08-14-2007, 12:35 AM
#2
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AFR doesnt make 76cc heads. The largest they make is 72.They had originally considered making 76's but they never did. Milling to 59cc's would be wayyyyy to much. Your better of starting with the smaller chambers, THEN milling them.
Originally Posted by LS1-Master
i just want to ask what is the maximam you can mill the AFR 225 heads to.
they came with 76cc and LG mill them to 59cc so can they go to more then this?
they came with 76cc and LG mill them to 59cc so can they go to more then this?
08-14-2007, 10:03 PM
#4
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Originally Posted by DaddySS
What are you trying to accomplish?
it have -4 pistons.
i want to take the compression up to more than 12.5:! so i will mill the heads.
08-15-2007, 10:13 AM
#5
Originally Posted by Tony Mamo @ AFR
Seems I get a few questions a week concerning milling AFR heads....how much is OK....will it hurt flow, etc. etc.
As I have stated earlier in a few other threads, milling our heads for higher compression does have a negative effect on head flow, but only when the mill becomes "excessive"....Note my response to a private message I received earlier inquiring about this exact situation. I thought it was good information that would help everyone out and save me from answering everyone on a "one on one" basis long term.
As I have stated earlier in a few other threads, milling our heads for higher compression does have a negative effect on head flow, but only when the mill becomes "excessive"....Note my response to a private message I received earlier inquiring about this exact situation. I thought it was good information that would help everyone out and save me from answering everyone on a "one on one" basis long term.
Conservatively milling our heads for more CR doesn't pose a problem. A good rule of thumb is to try not and take much more than .035 off the deck....once you exceed that figure you can see the flow numbers start getting softer fairly quickly (kind of looks like an "X squared" curve if you were to plot mill amount versus flow losses). Up to .030 is safe...even .035 isnt bad, but start pushing it much past .040 and you start to offset the gains in CR by the loss of headflow. A better situation at that point would have been a different piston design that had more positive dome volume...be it a flat-top versus a dish, or a small "pop-up" versus a flat-top etc.....any situation that would allow for the same CR without having to mill .040 + off the deck. Then you would have all the benefits of the higher compression without any of the downside side-effects of the loss in headflow.
Don't forget guys....use .006 per cc to figure out what you need to achieve the correct chamber volume...this way you can figure whether a different piston configuration might be better than another to help you get to the final compression ratio you are shooting for.
Thanks,
Tony
Don't forget guys....use .006 per cc to figure out what you need to achieve the correct chamber volume...this way you can figure whether a different piston configuration might be better than another to help you get to the final compression ratio you are shooting for.
Thanks,
Tony
Last edited by PREDATOR-Z; 08-15-2007 at 12:37 PM.
08-15-2007, 12:34 PM
#6
TECH Senior Member
Originally Posted by LS1-Master
i have ls2 402 with AFRs 225 76cc 10.1:1 compression.
it have -4 pistons.
i want to take the compression up to more than 12.5:! so i will mill the heads.
it have -4 pistons.
i want to take the compression up to more than 12.5:! so i will mill the heads.
