Plug heat range vs Altitude
10-19-2011 | 04:19 PM
#1
Plug heat range vs Altitude From NGK:
"Advancing ignition timing by 10° will cause the spark plug tip temperature to increase by approximately 70° to 100°C. NGK"
Doing the math on that based on my tuned high octane tables I'm in the +35 to +50 degree C range in terms of tip temp increase on a half-range COOLER than stock plug (NGKTR60 vs NGKTR55). I swapped the plugs one range cooler before the dyno.
Now I didn't take into consideration that I'm living @ 4500FT above sea level, which on the best days I'd be lucky to touch 90 kpa BARO, today it was 88kpa, WOT under 88 kpa my MAP is 84-85 kpa. Which brings me to my point that I'm down at least 15, probably closer to 20% in cylinder pressure, less pressure = lower temps, lower temps = need hotter plug.
Think it's worth dropping back to the stock heat range with current timing, or would I have to drop a few degrees or am I just thinking about spark plugs too much?
Anyone have a cylinder temperature equation I can waste my time on?
"Advancing ignition timing by 10° will cause the spark plug tip temperature to increase by approximately 70° to 100°C. NGK"
Doing the math on that based on my tuned high octane tables I'm in the +35 to +50 degree C range in terms of tip temp increase on a half-range COOLER than stock plug (NGKTR60 vs NGKTR55). I swapped the plugs one range cooler before the dyno.
Now I didn't take into consideration that I'm living @ 4500FT above sea level, which on the best days I'd be lucky to touch 90 kpa BARO, today it was 88kpa, WOT under 88 kpa my MAP is 84-85 kpa. Which brings me to my point that I'm down at least 15, probably closer to 20% in cylinder pressure, less pressure = lower temps, lower temps = need hotter plug.
Think it's worth dropping back to the stock heat range with current timing, or would I have to drop a few degrees or am I just thinking about spark plugs too much?
Anyone have a cylinder temperature equation I can waste my time on?
