[uk_figs]

Had high CHT's on my first flights today and am trying to determine whether I have a problem to solve or not. Engine is new ECI 0-360, climb out speed was 110 mph and CHT's reached 430 before I leveled out on downwind and reduced power and richened the mixture. CHT's then slowly reduced. According to the ECI break-in instruction you need to run full power for a few hours to seat the rings but I have also read in some other threads here that CHT's above 400 can "cook" the nitride process and ruin the cylinders (which I obviously do not want to do on my new expensive engine). I have the latest Van's baffle kit installed so am not quite sure what I should do next, also I am at a fairly high altitude airport (4600ft) which may not help.
Any constructive advice from the engine guru's appreciated.
Thanks

 

[vlittle]

Hi Dave.
A lot of us have had to rejet the carb to bring cylinder temperatures down. I had similar temps with an O-320 and there was no noticeable lean peak. That indicated a lean carb, and a rejet fixed the problem.

Vern

 

[L.Adamson]

Dave:

Keep the mixture full rich and do not lean during break-in. Maintain pattern altitude if you can; if not, cruise full power and full rich 1500' over the pattern. Keep a close eye on oil temps. Upon level-off, note the peak oil temperature. When the rings seat, you will notice a slight drop in oil temps. At that point, you can begin to reduce power.

At our airport altitude (4600'), engines kind of run like c-r-a-p when running full rich. We even lean right after engine startup, as the smoothness or lack of, is quite noticeable. Full rich leads to fouled plugs around here. I've had to clear fouled plugs a couple of times, because I wasn't running lean enough. We'll usually be flying at a minimum of 6500' msl, just to get over the lowest hills, and out of town; in order to rev the engine.

L.Adamson

 

[AlexPeterson]

Congratulations on the first flights!

Dave, try increasing your climb speed to something around 120 knots, or about 140 mph. It may seem like your climb rate will drop, but it won't drop much, if any. These planes are limited in climb speeds by high cylinder temps, which is an indicator of proper cooling for cruise without excessive drag (a good thing).

BTW, 430F does not seem unusual for a climb speed of only 110 mph on a new engine. What was OAT?

 

[uk_figs]

OAT was about 65F

OAT was about 65F, also I am running straight Slic mags not E/P mags. My biggest concern is the inputs about going over 400 degrees will damage the cylinders. ECI break-in instructions talk about not going over 400 during the short ground run phase but then talk about maximum cylinder head temps ranging from 450 - 525 depending on engine type.
With respect to Vern's comment on the carb it is a new precision carb that is supposed to be the correct one for the engine, how can I tell what type of jets I have and whether they need changing (is there a write-up somewhere)

 

[vlittle]

OAT was about 65F, also I am running straight Slic mags not E/P mags. My biggest concern is the inputs about going over 400 degrees will damage the cylinders. ECI break-in instructions talk about not going over 400 during the short ground run phase but then talk about maximum cylinder head temps ranging from 450 - 525 depending on engine type.
With respect to Vern's comment on the carb it is a new precision carb that is supposed to be the correct one for the engine, how can I tell what type of jets I have and whether they need changing (is there a write-up somewhere)

I had a new Precision carb as well with my Aerosport engine. When I had the problem with high CHT at take-off, I called them and they immediately offered to rejet the carb. This is quiet common from my experience.

Search the forums, I think there are a number of postings on this issue. You can check by operating at cruise speed, full rich and then leaning the mixture. If you can't see you EGTs vary about150 to 200F from full rich to lean peak then investigate further.

I had 430F CHTs in January (40-50F sea level temps) before this mod.

Also re-check your timing.

Vern

 

[mahlon_r]

Before the next flight, lean the engine on the ground, at full power, and see how much leaning capability you have. I find it hard to believe that a standard un-modified carb would be too lean at a close to 5,000 foot field elevation. It says you were leaning on take-off, so make sure you aren't leaning too much for the altitude! Only lean if the engine is rough or grumbly from being to rich and if leaning for that reason, only lean enough to make the engine smooth out and no more.
If you have to lean at full power to get the engine to run smoothly, enlarging the main jet in the carb will not fix your problem, as it will only make the engine run richer, full rich, and you are leaning it from full rich. So, having a richer, full rich setting will do nothing for you.
On the first few flights, seeing CHT's in the 430 area, during climb, isn't that abnormal. I would try to manage them for a few hours. Once the engine has settled in some, you should see those temps come down. In my opinion, I would wait a while to attack things unless the cht is totally unmanageable in the climb. If you don't see the temps come down within 25 or 30 hours on the engine, then it is time to think about modifications to carbs, baffles cowlings etc. For break in, I think you should run the engine at full power for take off and only lean enough to keep the engine running smooth and maximize RPM. Keep the climbs flat to promote the most cooling air! In cruise, I would run 70-75 percent power and not lean aggressively. Try to manage any of the cht values to below 450F( the cooler the better) in the climb and you should be OK.
Good Luck,
Mahlon
?The opinions and information provided in this and all of my posts are hopefully helpful to you. Please use the information provided responsibly and at your own risk."

 

[uk_figs]

Update after todays flight

OK today I put a couple of hours on the engine and here are the results:
1. Leaning for take-off but on the rich side, CHT climbed into the 440 but started to back down after I flattened the climb out at 140mph as suggested
2. In cruise at full throttle CHT's were in the 370's (390 on #3) as long as I had the mixture full rich, EGT's were around 1275 - 1325
3. If I tried to lean the engine much at all the CHT's started to climb into the 400's
4. At full rich occasionally the engine stuttered for about 1 sec, happened about 3 times in the 2 hour flight, (fouled plugs?)
4. Typical altitude was 6500 outbound and 7500 back, OAT about 65
The flat and faster climb speed seemed to help keep the temperatures down, oil temp hit 200 at one point with full throttle.

How do these numbers look, is this just typical of breaking-in a new engine?
Thanks for all the feedback.

 

[vic syracuse]

Dave, how much range do you have on your EGT's at cruise between full rich and full lean? You should have somewhere in the neighborhood of 150 degrees. If not, you are too lean. Try that on your next flight.

Vic