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Old 06-06-2001, 08:51 AM
johngray johngray is offline
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Join Date: Aug 2000
Posts: 82
Pinging results from a complex relationship between octane, spark timing, engine temperature, ambient temperature, engine load and speed, engine compression, and even ambient humidity. Small changes in any of these can make a significant difference. A well tuned car should ping lightly on a long uphill gradient on a warm day. The "sound of economy" as some people call it. The two easiest variables to control are octane and timing. Sometimes if you retard your timing just one or two degrees from its current setting it will do the trick. Just don't overdo it. Some real old cars had a way to make adjustments to ignition timing from inside the car while underway so you could "dial it in" as you went. Water injection is also an effective way to reduce octane requirements. The Germans used it extensively on their fighter planes during WWII since they didn't have access to high quality gasoline like the Allies.
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