RE: Importance of engine break-in ?
I have a not so enjoyable experience...
I recently bought a TT F-75s, which is my first 4 stroker. I started to run it, and the guys at the field wanted to deal with my needles....and took me as a newbie.... (I'm new at the field), anyway I had about 30-40 minutes of total run time with the engine, and it took very good compression over the time, and since Idling was very smooth and slow since the begining, and the engine was responding good, they all told me...go fly..what do you want...an hour of running in etc....go flying!....and I said....ok...I wasn't sure because I felt it was completely run-in, but was running very good (over 9600RPM with the New Graupner 13x6). I don't know if it's a fact of the four strokers that they don't react much to small adjustments in needle valves (I've read here that it took about 3-4 seconds to respond), so I let it...I found a confortably sweet spot...and the plan took of...it was O.K, I knew I wasn't able to get all the power, about 5 minutes later, I thought that the engine turned off... I had no throttle response.... so I tried a dead stick landing...when the plane was close, I heard a nice idling from the engine..so it was still runing....but I couldn't have throttle response... loose linkage I thought (which wasn't)... so after a though landing, the new plane was safe...
When I took the plane, the engine was very very hot, I know 4 strokers run hotter, but it wasn't normal, compression was still really good, so I took of the engine cowl, the engine was very hot... linkage was good and working, everything seemed ok... So I guess that the engine just didn't wanted to work more because of the overheating... Good that I was using fuel with 22% castor oil...
Is this kind of behavior to expect when a 4 stroke engine is overheated?, that it doesn't pick up RPM's ?
Anyway I've learn my lesson.... I should have more confidence with what I know about the engines (specially the one adquired here)...and second..... Don't fly your plane untill the engine is completely broken in!!
Saludos,
Jorge