Running Too HOT
 

RV9A, IO360. Catto Tri-prop. I am now 16 hours into my phase 1 flight on normal cruse seeing 385F CHT at 3,000' cyl. #1 the hottest running, OAT is 76F. On climbs at that altitude 500 FPM they can all push over 400F. what actions have some of you guys performed to bring these temps. down?? Thanks, Mark C. 119RV

Do you have the standard Van's baffle kit with the air dam in front of cyl #1? If so, try cutting it down or removing it. Inlet air ramps installed? I had to remove and re-glass my inlet ramp forward on the right side. This provided more area above #1 and brought temps down about 10 degrees. Absolutely sure your baffles are sealed everywhere?

Also, is it a new engine? If so it will probably cool down a good bit as it breaks in. And lastly, do you have wheel pants and fairings installed? I just installed my main gear fairings and saw a gain of 5-7 knots and temps down another 8-10 degrees.

I am at a similar point in Phase 1 as you. My goal is under 400 all the time - right now #1 creeps over 400 in a climb (it's also 90 degrees OAT...). I'm getting close, and think that adding wheel pants and front gear fairing will do the trick.

Chris

thanks, Chris... New Engine, stock Vans baffles very well sealed. No wheel pants yet on any of the wheels. I have cut down the forward air dams about 1/2 inch. It make sense as others have stated just take them out.. Mark C.

Get the wheel pants on. I saw 10-15 degree drop in CHT's once installed. I have an IO-360 with hartzel CS prop. Your numbers don't seem too far off from what I saw during initial break-in without wheel pants. I also removed my air dams too.

Your numbers are very close to mine, though #4 is my hottest. I am just finishing up the wheel pants now and we'll see what that does. I ended up cutting my lower cowl exit area about 1" forward of the firewall during the first part of Phase 1, that helped quite a bit. I may end up putting it back in and installing the Anti-Splat louvers for climb cooling, we'll see.

What RPM do you get on take off and early climb out, what speed are you climbing at and what is the fuel flow and MP just after take off?

You would not be the first person to have an FCU that does not flow anywhere near enough fuel.

Be Patient
 

I would track temps, but don't worry too much till you have 40+ hours. My engine took over 40 hours till temps came down. Also wheel pants will make a difference.

Steve

Thanks all, great input I will get the wheel pants on and keep pushing the hours,16 presently. I'm, getting painted in Sept. so flying and learning the airplane is a priority. Spoke with Ken at Vans today his fix to lower CHT temps on the upfront cylinders cut out the baffle air dams. He liked the idea that someone had to add nut-plates so air-dams can be added back in the Winter.. Mark C. 119RV

I cut my air dams off and saw no need for them during Chicago winters. CHT distribution was the same in winter. All CHTs lowered about the same amount i cold weather flying.

Larry

I had a high #3 for many years and finally put a small bypass behind the cylinder so air can go around and get to the bottom fins (described in a "hot CHT #3 thread on here somewhere). Dropped the #3 by 40 degrees and all the others by 10-15 degrees. Used to be on hot days I had to climb, level to lower CHTs and then climb again, but now I can pretty much climb with impunity. I also have a Catto 3-blade set up for cruise, so it tends to heat up a bit more in the climb phase with less air going through the system.

YMMV

Greg