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Re: detonation vs compression, static or dynamic??
[Re: dogdays]
#1471177
07/23/13 08:19 PM
07/23/13 08:19 PM
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Joined: Feb 2007
Posts: 6,295 U.S.
moparniac
master
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master
Joined: Feb 2007
Posts: 6,295
U.S.
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Altitude will affect dynamic cranking compression and dynamic compression ratio. The cooler weather racing will cause the numbers to go up. So "figure" up your pump gas build at zero altitude type racing weather. The cam specs your posted do not show timing events either the higher the Intake Valve closing ABDC greatly helps.
Mopar Performance
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Re: detonation vs compression, static or dynamic??
[Re: moparniac]
#1471178
07/23/13 08:38 PM
07/23/13 08:38 PM
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Joined: Oct 2007
Posts: 4,210 New York
polyspheric
master
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master
Joined: Oct 2007
Posts: 4,210
New York
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"Altitude will affect... dynamic compression ratio."
How?
Boffin Emeritus
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Re: detonation vs compression, static or dynamic??
[Re: Kern Dog]
#1471180
07/23/13 10:23 PM
07/23/13 10:23 PM
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Joined: May 2008
Posts: 5,399 Aurora, Colorado
451Mopar
master
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master
Joined: May 2008
Posts: 5,399
Aurora, Colorado
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The Dynamic compression "ratio" stays the same, but the cylinder pressure is reduced with altitude. A dynamic compression ratio of 8:1 should create cranking cylinder pressures of about 163.5 psi at sea-level (14.7 psi air pressure), but around Denver, the air pressure is around 12.0 psi, so the same engine (dynamic compression of 8:1) would only have a cranking cylinder pressure of about 133.5 psi. FWIW, 7:1 dynamic at sea-level (137.2 psi) is about the same cylinder pressure as 8:1 dynamic in Denver.
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Re: detonation vs compression, static or dynamic??
[Re: 451Mopar]
#1471181
07/23/13 10:46 PM
07/23/13 10:46 PM
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Joined: Jan 2005
Posts: 12,423 Kalispell Mt.
HotRodDave
I Live Here
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I Live Here
Joined: Jan 2005
Posts: 12,423
Kalispell Mt.
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2000 ft to 4000 foot and 95 degrees, factory timing on my mac mentor shows around 30* at and near WOT. Never heard of a 318 getting a death flash only 5.9s. I actually had more pinging before milling the block and going to thinner head gaskets.
I am not causing global warming, I am just trying to hold off a impending Ice Age!
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