T

Turbofan

Active Member
Just got rv4 running IO320, airflow performance injector system, can't even climb above 2000 feet without #3 CHT hitting 500. Have to level off and pull throttle. All Others IN 300 Range when it overtemps. Stock setup, Baffling looks fine both sides, no space behind cylinders. All cylinders Peak About Same Time On EGT gage so I don't think it's lean. Stock long cowling we it 13 in spinner, running autogas. Thinking about opening one inch space behind #3 in baffling.
 
Probably a defective sensor. Swap with another to check. But first, 500 if a real reading is something you want to fix on the ground before another flight. Drain the autogas from at least one tank and replace with 100LL. That will eliminate speculation of detonation from lower octane gas. Check to verify the injector for that cylinder is no partially blocked. Put a couple new plugs in that cylinder to eliminate the possibility of a bad plug. I am sure you will get more suggestions. I have abused a lot of cylinders by ignorance, equipment malfunction, daydreaming instead of flying but never seen a 500 degree CHT. Please fix before flying, right next to 500 is failure of that cylinder.
 
Check everything else before you change the baffling,
that is reserved for fine tuning.
What kind of instrumentation do you have and by any chance is it recording
your engine parameters?
Showing 3 of your 4 cylinders around 300F, it is almost inconceivable that
one them is actually at 500F as early as 1 minute into the climb.
What does that cylinder show at run up rpms?
 
Did you observe the EGT on #3 at the time of 500 CHT? If normal, that eliminates detonation as the cause.

I would not too quickly dismiss the possibility of a plugged injector and accurate sensor. That is far more common on a new system, where contaminants have many ways in via the installation. Also, he is in the ring seating phase, assuming the engine wasn't run in a cell for an hour or two first. I had someone playing with the mixture on my first flight and the CHT quickly hit 460 before I shoved it full rich (this 30-60 seconds at that temp was enough to glaze the cylinder by the way). That was in the first hour of running with no test cell time. 500 is not out of consideration for an engine that's seen less than an hour or two, depending upon the hone finish used.
 
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