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| None of the "closed" chamber heads had hardened exhaust seats needed for unleaded gasoline, and these heads are coveted, plus the production numbers were far less than the peanut ports. | | None of the "closed" chamber heads had hardened exhaust seats needed for unleaded gasoline, and these heads are coveted, plus the production numbers were far less than the peanut ports. |
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− | ==Static CR==
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− | *[http://www.wheelspin.net/calc/calc2.html SCR]
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− | ==Dynamic CR==
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− | *[http://www.wallaceracing.com/dynamic-cr.php Wallace Racing DCR calculator]
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− | *[http://www.empirenet.com/pkelley2/DynamicCR.html Kelly DCR calculator]
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− | *[http://www.uempistons.com/calc.php?action=comp2 KB/Silvolite DCR calculator]
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− | *[http://www.rbracing-rsr.com/comprAdvHD.htm RSR DCR calculator]
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− | {{Note1}} Some dynamic compression rtatio calculators (like KBs) ask for an additional 15 degrees of duration be added to the IVC @ 0.050" lift point figure. This works OK on older, slower ramped cam lobes, but the faster lobe profiles may need to have 25 degrees or more added to be accurate.
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− | {{Note1}}If the intake valve closing (IVC) point isn't known, it can be calculated:
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− | # Divide the intake duration by 2
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− | # Add the results to the lobe separation angle (LSA)
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− | # Subtract any ground-in advance
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− | # Subtract 180
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− | This result does not need to have any amount added to the IVC point, like the KB calculator calls for.
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| ==References== | | ==References== |
− | [http://www.carcraft.com/techarticles/ccrp_1010_cheap_big_block_chevy_engine_build/index.html Car Craft 454 build] baselined with peanut port heads, 446 hp at 4,900 rpm and 542 lb-ft at 3,600 rpm. | + | [http://www.carcraft.com/techarticles/ccrp_1010_cheap_big_block_chevy_engine_build/index.html Car Craft 454 build] baselined with peanut port heads, 446 hp at 4,900 rpm and 542 lb-ft at 3,600 rpm |
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| [[Category:Engine]] | | [[Category:Engine]] |