Originally posted by afm
All of the following conditions MUST be met before any temperature can be considered correct, assuming the engine is in good shape.
1.-There must be a visible trail of smoke when accelerating from EVERY corner.
2.-The idle is stable.
3.-The glow plug wire stays somewhat shiny and the coil stays round (UN - DISTORTED).
4.-The performance is good.
I find the most important tell tale thing that says your engine is healthy is by the way the engine idles coming into the pit lane after a few hard runs. It should be low and steady without skipping a beat.
Of course it should not idle forever but when the engine comes back in the pits after a hard run, it should idle good and steady. Engine that fires up straight after being very cold and "seem" to idle steady right after that should be very careful. Their low end is probably very lean.
After the engine ilde indicator, I would then go for no. 3, no. 1 and no. 4 in that order as indicators for a good and correct engine tune. Some mod engines can be run rich and yet be as fast if not faster than stock. So performance is quite relative here. As for trail of smoke, not all fuels will exhibit this. Some will give you very little to no smoke at all. Some will give you lots of smoke even at lean conditions.
My 2 cents.