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#1
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Hot rear engine
before anyone says anything, I did the search and did not find my question answered.
We have recently installed a 0 SFREM engine as our rear engine. My mechanic made all new tin and baffles, and it is sealed tight. Having said that, I am puzzled. On our first flight, today, the rear cylinder head temp went right up next to 400, and stayed there. We did a short hop (mech and I), about 10 minutes, landed, made some adjustments, and flew back. Temps still up a lot. If I pull back on throttle (stay above 18, the book says) and revs about 2300, it dropped some, but not a lot. Rear cowl flaps were opened all the way. Would closing them help? Is this semi-typical of first flights in a new rear engine? Does anyone know? Monday, I hope to get the 2 hours they recommend in, and see how temps are. I am puzzled, I would think that it is a new engine, but temps shouldn't be that high, especially since it's 40 degrees outside. EGT was reading the same for both front and rear engine. Mine is 337D, normally aspirated. Front engine temps were on the low side. I have single probe cessna gages. Speaking of that, how can we get the tach gages checked, calibrated. Does anyone know? Thanks 
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#2
03-25-05, 01:33 PM
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Larry gald to see your flying again.
I talked to my IA today and said that the temps should be high at 1st and come down after about 20 to 30 min of flying. He said just me mindful of the oil temps that tey don't get to high. That would be a sign of trouble. He said some times you just get a very tight rebuild. He would fly it for an hr or two as they recomend but watch the oil temps. Kevin
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#3
03-25-05, 03:00 PM
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This was my experience as well with my remans (both front and rear). I think my IA told me to run it hard, 75% power, mixture very rich, for the first hour or two. Mine ran hot like yours, but you could watch the temps go down, even towards the end of the first hour.
Kevin
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#7
03-26-05, 10:00 AM
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The hot running during breakin is why you need to run VERY rich or do the breakin like we do, LOP. It will run much cooler. As soon as the rings seat, the CHTs will come down a bit.
The science suggests strongly that the best way to break in an engine is at high mean pressures (high HP) and with cool CHTs. That is best accomplished LOP if that is an option. If you cannot run LOP due to poor F:A ratios, then keep it very, very rich. I broke in my TNIO-550 in December at about 85-90% power, at about 70dF LOP and was completely finished with the breakin process in 3.5 hours. It rarely takes more than 4.5-5 hours. That's how we have broken in the last 100 plus engines. It works exceptionally well.
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Walter Atkinson Advanced Pilot Seminars
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