Does fly cutting = Lower compression?
04-05-2008, 04:38 PM
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Does fly cutting = Lower compression? I would probably never have a need to flycut pistons, but just for my knowledgebase, wouldn't this lower your compression? It seems like the combustion area would increase (as would the BDC area) but since it's a ratio the same increase in TDC are would raise compression slightly.
04-05-2008, 04:42 PM
#2
Negligible.. you are taking a small relief cut of maybe .030 in 1 little area, though I never measured it, think of it in cubic centimeters. 1/2? maybe? Taking .006 off the deck for the whole combustion chamber is roughly 1cc, and I can't see it even being NEAR that.
04-05-2008, 05:03 PM
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Yes flycutting will lower your SCR, but this is usualy done with a head mill to gain more SCR yet increase PTV. valves are at 15* angle, so let us say you cut .080 (PTV gain) loss 2cc, but you mill heads 4>5cc, you get my drift.
04-05-2008, 05:12 PM
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Flycutting is usually accompained my a head mill, and the head mill compression will usually be a lot more than the compression loss from the cutting alone.
Me having the -2cc pistons allowed me to mill the **** out of my heads to get nice high compression, use a thin gasket for tight quench, and still have good clearances.
Me having the -2cc pistons allowed me to mill the **** out of my heads to get nice high compression, use a thin gasket for tight quench, and still have good clearances.
04-05-2008, 06:44 PM
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Thats interesting stuff. You learn somthing new every day I guess. Dont wanna high jack this thread but does fly cutting a piston weakin it at all? As far as a stock piston goes.
04-05-2008, 07:29 PM
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thanks guys. Honestly a senseless question on my part because I don't think i would ever have a cam large enough for that to be an issue, just curious. Cheers!
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04-06-2008, 09:28 AM
#10
Flycutting is one thing that I would like to do in the near future. I figure I can then go with a slightly bigger cam, and then go with a 0.040" head gasket and keep my scr and dcr but have the benefits of a larger cam.
I just am a little hesitant doing it on my own the first time.
I just am a little hesitant doing it on my own the first time.
