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Re: 440 Dynamic Compression and Pump Gas
[Re: Dodgem]
#1179444
02/19/12 07:48 PM
02/19/12 07:48 PM
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Joined: Mar 2010
Posts: 1,880 Out in Left Field, NY
bobs66440
OP
top fuel
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OP
top fuel
Joined: Mar 2010
Posts: 1,880
Out in Left Field, NY
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Quote:
Pretty sure wallace uses .050 numbers it's the same as this
http://www.rbracing-rsr.com/comprAdvHD.htm
Static compression ratio of 9.35:1. Effective stroke is 3.39 inches. Your dynamic compression ratio is 8.57:1 . Your dynamic cranking pressure is 173.77 PSI. Your dynamic boost compression ratio, reflecting static c.r., cam timing, altitude, and boost of 0 PSI is 8.57 :1. V/P (Volume to Pressure Index) is 210
I have a detailed dyno program and it gives the same cranking compression!
Hmmm, Using that calculator, I got the same result as you, except as I understand it, you are supposed to add about 30* (which would make it 70* seated) to the Intake Closing to correct for the @.050 number because the chamber doesn't start building pressure until the valve is fully seated. Maybe that calculator automatically adjusts for that?
I used the one listed DCR Calculator with VB6 Runtime files at the bottom of the page on this site.
http://cochise.uia.net/pkelley2/DynamicCR.html
It calculates dynamic stroke length, cam timing / overlap and static and dynamic compression, but it uses seat to seat (advertised) timing, not @.050 specs. Maybe try that one and see what you think? I keep coming up with 7.054:1. This is very confusing.
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