Q: I fly a Cessna 182S registered HP1401. It has a Lycoming IO-540-AB1A5, 3 blade prop. Sea level OAT is 90°F or so year round.
It had a single probe analog CHT display connected to cylinder #1, which always remained around 320°F.
I then installed a digital engine monitor, which showed the rest of the cylinders easily getting into the 400°F range. So I started flying lean of peak with GAMI injectors and cowl flaps fully open all the time and got the CHTs into the 360°F range.
The original engine reached its 19th birthday and some 1,900 hours, so I decided to replace it with a factory rebuilt.
The test data sheet from Lycoming shows all temps completely normal at the factory.
I just flew the first two hours with the new engine, and it’s running much hotter than the old engine, particularly cylinder #2. In order to keep the temp at 400°F or below, I have to keep cowl flaps full open and keep the mixture around 19 gallons per hour. [Read more…]