2nd Engine Run Without Cowling...

Today I helped a friend with his 2nd engine startup. Engine was run for the first time about a month ago and run time was fairly short. Today we installed the wings and ran the engine for the second time. Both engine runs were with complete front cowling removed. Oil cooler was suspended and held in place with safety wire. OAT today is 87F. All temps stayed in the green except for CHT. Both CHT?s were in the mid-230F (yellow) range.

I suspect the water radiator does not provide sufficient cooling unless lower cowling air duct is in place and preferably the airplane is flying through the air. Does this theory sound right? My RV-12 has always showed CHT?s less than 200F.

Another question? there is a straphanger for an oil hose that runs through the loop of the right front exhaust tubing (sorry no picture). The hose with fire sleeve is very close the exhaust tubing. My 12 has thermal wrap on the right front exhaust tubing. Any comments welcomed.

Your theory sounds right.
I went flying today with OAT around 90 F. My CHT got up to 225.
From what I have read, it is a bad idea to wrap the muffler because doing that will cause corrosion. The same principle probably applies to the exhaust pipe.
I wrapped the fire sleeve with metal tape right above the pipe.

Piper J3 said:

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Another question? there is a straphanger for an oil hose that runs through the loop of the right front exhaust tubing (sorry no picture). The hose with fire sleeve is very close the exhaust tubing. My 12 has thermal wrap on the right front exhaust tubing. Any comments welcomed.

Click to expand...

That oil line very close to the #1 exhaust pipe has been discussed before and here is one way to mitigate the heat without wrapping the exhaust pipe. Add a second hole further up on the strap to move the adel clamp up and optionally wrap the oil hose with left over heat tape from the cowling work.

Tony's lead

I did a similar wrap using a shielding material and secured it with metal tie wraps. Needed? But I felt better about the close proximity of the hose to the exhaust pipe. IMHO

I just rotated the strap upward to get the maximum clearance. Did not wrap the hose. No problems so far, 260 hours.

heat deflector shield?

what about putting one of those heat deflector shields on the lower exhaust pipe.