Ever since first flight, I've been struggling with high CHTs on my back two cylinders (#5 & #6). With WOT and full rich, I'd see #6 climb through 400 degrees pretty quick if it was any hotter than 65 OAT. By the time I would notice, and react, it'd usually make it to 405-410 range. Usually, I'd pull the throttle back to about 23" or so, sometimes lower.
The first thing I found that helped was the washer behind the back cylinders (between the baffle and the cylinder). That helped, but only by slowing down the progression to 400+ during climb out. It also helped in cruise.
Last week, I went to Spartanburg to visit AirFlow Performance for injector tuning. After the first flight with Don, the analysis showed that #3 & #4 were running rich and #5 & #6 were lean.
Cue to me smacking my head and wishing I had a V8 (the drink, not the engine). Why didn't I make that connection before? Anyway, Don makes some injector adjustments and we go fly again, climbing up to 8500'. I was able to leave it WOT all the way up, and even was able to start leaning a bit in the climb too, and never did I get close to 400CHT.
After one last injector adjustment (#1 was showing slightly rich), I left for home. Oh boy, what a difference. Again, WOT climb out to 8000' (OAT on the ground was 84F). Highest CHT observed was 387! This is easily 20 degrees cooler than the previous setup.
This may or may not be a solution for everyone, but wanted to throw it out there as another potential solution for high CHTs. Don at Airflow Performance was fantastic to deal with and has a wealth of knowledge he's very willing to share. Well worth the trip up there to have this done.
Oh, for the record, my engine is a stock IO-540 from Van's with two mags and Silverhawk throttle body.
The first thing I found that helped was the washer behind the back cylinders (between the baffle and the cylinder). That helped, but only by slowing down the progression to 400+ during climb out. It also helped in cruise.
Last week, I went to Spartanburg to visit AirFlow Performance for injector tuning. After the first flight with Don, the analysis showed that #3 & #4 were running rich and #5 & #6 were lean.
Cue to me smacking my head and wishing I had a V8 (the drink, not the engine). Why didn't I make that connection before? Anyway, Don makes some injector adjustments and we go fly again, climbing up to 8500'. I was able to leave it WOT all the way up, and even was able to start leaning a bit in the climb too, and never did I get close to 400CHT.
After one last injector adjustment (#1 was showing slightly rich), I left for home. Oh boy, what a difference. Again, WOT climb out to 8000' (OAT on the ground was 84F). Highest CHT observed was 387! This is easily 20 degrees cooler than the previous setup.
This may or may not be a solution for everyone, but wanted to throw it out there as another potential solution for high CHTs. Don at Airflow Performance was fantastic to deal with and has a wealth of knowledge he's very willing to share. Well worth the trip up there to have this done.
Oh, for the record, my engine is a stock IO-540 from Van's with two mags and Silverhawk throttle body.