Hot rear engine

[Walter Atkinson]

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.