Comment

Comment by David Gallagher on May 19, 2009 at 7:33am

Well I can't say that my CHT's plummeted after 50 hours on their own, but I have been able to make changes to get them down. Comparing apples to apples, I took a recent flight with an OAT of 75F to an early flight last year of the same temp. Back then with about 5 hours on the engine, I saw CHT's between 276F and 338F. Now with 76 hours, I see 283F to 308F. Playing with EGT to even out the heat loads probably had the most effect on lowering the higher CHT's. Playing with dam heights was the other. Last year, cylinders 2, 5 & 6 were, by far, the hottest on both CHT and EGT. Now 2 & 6 are the hottest on both parameters, but they lie a lot closer to the rest of the pack.

Comment by Paul Hammond on May 18, 2009 at 5:48pm

yesterday at10c OAT chts 130-138c oil 75c 2600rpm 4000amsl105knts

Comment by Stephen R. Smith on May 18, 2009 at 9:21am

I just pulled up the data from a one-day 1,100 mile flight. I removed the takeoffs and landings. Here are the averages.

RPM 2,678

CH1 288 -3
CH2 300 +9
CH3 298 +8
CH4 314 +24
CH5 235 -55
CH6 306 +16

AVG 290

#5 is "sick". It ether has a spark problem or compression problem. I will learn which it is when I do my second annual at the end of the month. The engine has 530 hours on it.

I am running the "stock" cooling system except for two changes: 1) I have the gull wings on the bottom instead of the top. 2) I have an eyebrow above the opening on the pilot’s side to maintain good airflow during climbs. All my CHT problems vanish after adding the eyebrow.

Comment by Juan Vega on May 18, 2009 at 9:05am

remember first 50 hours it will run hot, then plummet after that. My numbers the first fifty were above 300, then they come down quite a bit.

Comment by Mark Ertz on May 17, 2009 at 7:49pm

There are Varibles. The 3300 w/ Hydratic lifts runscooler. The prop makes a difference. a flat dam at the front cylinders is a major factor in cooling. That front dam must be vertical and cover more than half the front cylinders in order to pressurize the air duct system wel. For $20 you could put vortex tape on your prop that will help cooling of the cylinders. The vortex tape is from stolspeed inc or you can buy it from spruce.
The 3300 can run continous up to 356 as stated in the manual. In climb you can run it up to 392 for short periods of time. Phillips X/C 15w50 is a good recommended oil. The aeroshell runs in and out like water. The X/C really coats things better. Generally, my CHT indicate 320 or so. It takes ten minutes of cruise to really see a trend. I use a 51 pitch cruise prop. Jabiru is talking up the 49 pitch for more rpms & cooling. But that depends on your flying style. I cruise above 7500 a lot. IF you are a bottom dweller, a climb prop is a better call. Here are my numbers:
idle 800
static 2450
climb 2600 @ 600 fpm @ 90 mph
criuse 2600 -2750 @ 3000 ft @ 115 - 130 mph
full 2950 @140
Bis Spater

Comment by Paul Hammond on May 17, 2009 at 7:31pm

at 41c OAT 160,160,156,160,165,160,oil90 psi42 you can do the conversion it was ahot time here in summer, now in nearly winter OAT15c,142-150,oil 75c static prop 2650rpm 35hours

Comment by Juan Vega on May 17, 2009 at 5:10pm

I just finished my 211 hour oil change and test flew the plane with static prop at t/o of 2850 rpm. the cht temps running at (from back to front) 300, 298,280, 276, 250,249. Oilpressure at 38 psi, 162 degrees F. OUtside air temp 100 farenheit, Density Alt 2100 ft. Hot Hot Hot!!

Juan Vega