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Well, actually it is absolute pressure that the spark plug
is reacting to. In this example, the absolute pressure in the intake is
1.234" HG higher at 10,000 with your 26 " boost than at sea level with your 36"
of boost.. This would contribute to an increased pressure in the
combustion chamber when it is compressed over the sea level compression
pressure. Therefore, the spark plug is facing a tougher task at 10,000
than at Sea level (in this example).
Ed
----- Original Message -----
Sent: Monday, September 05, 2005 12:57
PM
Subject: [FlyRotary] Re: Another great
flying day = another day of troubleshooting
Actually, Dave you had a higher pressure ratio (manifold to
ambient) at 10,000 feet with 26" boost than at sea level with 36".
At sea level the pressure ratio would be 36/29.92 = 1.20. At 10,000
ft ambient pressure = 20.57 " hg , so the pressure
ratio would be 26/20.57 = 1.26. Not much
greater, but it was higher by approx.1.23" Hg. (1.20 -1.26 = .06 *20.57 =
1.234" Hg).
Ed
A Right. But what does the
plug know about the ambient pressure? I thought that it was just the
absolute density of the charge that was contributing to SAG.
--
Dave Leonard
Turbo Rotary RV-6 N4VY
http://members.aol.com/_ht_a/rotaryroster/index.html
http://members.aol.com/_ht_a/vp4skydoc/index.html
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