CHT's for the Lyc O-540

[Cole R182_Retract]

What CHT's can be expected at 75% power and 7500' MSL for the non-turbo Lycoming O-540 engine. Would like to see if there are major differences between the 1978/79 R182 and the 1980+ R182 with the newer cowl design and updated baffles. I am mostly interested in ROP numbers.

[jelecroy]

I normally aim for CHTs between 360 and 380 in cruise. Normally see that in cruise with the cowl flaps closed. That's at a typical power around 70 to 72%, and fuel flow a little under 12 gph. If I'm al low altitude I try to reduce RPM to 2300 or even 2200, and make up the power with manifold pressure,

If CHTs are higher, I look for the reason. Often it's one or more of the cooling baffles out of place. There are important rubber seals between the nose bowl and the forward engine baffles. If either of those rubber seal pieces in out of place, blown out below the engine, then a ton of air that comes in the nose flows directly into the lower cowl space without flowing through and cooling the heads first. Over the past three or four years I have replaced most of the runner cowl seal material to get goo cooling air flow.

The other thing I check is mag timing. Early mag timing will definitely create elevated CHTs.

[Cole R182_Retract]

Thanks for the information, it is very helpful. I plan to take possession of an R182 the beginning of November and your information will help me establish a baseline for what I should be seeing on the JPI 730 that is in the airplane.