We run onboard data loggers in our race planes...We measure the exhaust temp with the thermocouple right in the exhaust pipe flange at the cylinder..We try to maintain about 850F in the straightaways, and it will jump to 900 in the turns, then right back down to 850 in the straight..The engine manufacturer has run 1000 degrees exhaust temp on the engine dyno, with controlled air flow...He says the engines run best at about 350 head temp, measured under the spark plug...They fly 6 hour missions at 7000 rpm....350 is no problem, but like Dick says, you can't point a laser heat gun at the engine when it's on the ground and expect to get meaningful results, a well tuned ear works just fine...
Hey dick...35% oil ? 44.8 oz in a gallon ? I though my 20% was high