Originally posted by "CronicBurn"
Thanks for the info... How does the head raise compression by adding cc's to the head... How did you figure it would raise compression by .2cc? What formula or what not did you use?
Thanks.
By adding CC's to the head, you LOWER compression. Compression is figured on the volume of air compressed during the stroke.
Try This:
Compression Ratio =
Vbdc =
Vcyl + Vpc + Vdh + Vcch_
....................................Vtdc.......... ........Vpc + Vdh+ Vcch
..................................2............... ....................2
which equals
II(B/2)_ S + Vpc+ Vpc + II(B/2) _D +Vcch_
.............................................2
..........................Vpc + II(B/2) XD + VcchWhere:
B = bore,
S = stroke,
Vbdc = volume at bottom dead center,
Vtdc = volume at top dead center,
Vcyl = total cylinder volume,
Vpc = volume of piston crown,
Vdh = volume of deck height,
Vcch = volume of combustion chamber in head,
D= deck height.
After you think you got that figured out, go search the web for a "CR calculator" like
http://www.smokemup.com/auto_math/compression_ratio.php
Also, it's common knowledge that the ITR head is mildly ported and pollished... but 5.25% Where did you get this?
I stated that a B16a head flows 5.25% better than a B18c1 head, NOT a B18c5 head. These numbers? Flowbench.
Also If the ITR has the same cc's as the Si(B16a)... Then how would it not raise compresion by .2cc?
Here is what I said: Btw: the B16 head flows 5.25% better than the B18c1 head. The B18c5 flows better than the B16, but it doesn't raise the CR any.
The b18c5 flows better than the B16, but it doesn't raise the CR any (compared to the B16!) Understand now?
Charles
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