That number is in the ballpark, the exhaust gas temp depends on the compression pressure, timing of the spark, fuel lean-rich mixture etc.
some piston aircraft and OTR diesels have EGT gauges that the driver monitors for best operation.
Al

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2007 Mini Cooper 4K miles
1993 300E 2.8 120K miles
1961 Morris Minor 42K miles
1965 Morris Minor 23K miles
1997 Ford F150 235K miles
1987 Ramcharger 202K miles
1984 Chevy C-30 farm truck 88Kmiles
1968 XKE 59K miles
2001 Harley Softtail
2003 Harley Roadking