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AirEupora
Joined: 01 Nov 2009 Posts: 186 Location: Dixon, CA
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Posted: Thu Jul 12, 2012 7:01 pm Post subject: What is the relationship between |
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High cylinder temps and propeller pitch?
Today, I got the first good flight out of my Europa with the Jabiru 3300L. This is the seventh flight and I only have two hours on the engine. I have been chasing high cylinders temp and high oil temps. I'm getting close to having the oil temps under control. Most of it is getting the opening around the oil cooler correct. Right now 4 & 6 are running high CHT at full power. I'm only getting about two to three minutes of operation at these power settings. The RPM is starting to come up and I got 2900 for almost a minute.
EGT's are within 50 degrees of each other. I have a stock needle and seat. Not sure what the numbers are.
The reason I'm asking is I had a Navion and the prop company pitch it too high and my CHT were to high. Once I had it re-pitched the CHT came down and the oil temp came down.
I'm thinking I should do the same for this engine. Decrease the pitch on the ground adjustable prop.
Does anybody have any ideals or suggestion?
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BARRY CHECK 6
Joined: 15 Mar 2011 Posts: 738
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Posted: Fri Jul 13, 2012 1:07 am Post subject: What is the relationship between |
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Hello Mystery Man:
It takes HP to swing a prop. The three factors of a prop are:
1 - Weight
2 - Diameter and
3 - Pitch
Increase any one of these and more HP is required to maintain the SAME RPM. Increase any two at the same time you you may not get off the ground.
A higher Pitch requires Higher HP to achieve the same RPM.
Questions:
1 - Is your prop what is recommended for your plane?
2 - Is the pitch on the prop what is recommended for your plane?
3 - Is your engine broken in yet? <-- Two hours - Nope!
Since the engine is NOT broken in as yet and since you have a Ground Adjustable prop - I would set a low pitch for the break-in time.
Also what was the DA for the day you were flying?
CRAZY question - Did you assemble and install the the prop correctly?
I ask this because I saw one plane where the prop was installed BACKWARDS!!!
Now to address the oil cooler. Without seeing the oil cooler system it is impossible to comment on. But, here is a little trick that returns great advantages - Seal off the edges of the oil cooler with RTV so no air leaks around the cooler. You want o force as much air through the cooler as you can. Air like water will take the path of least resistance. Any cooler is a path of high resistance - So keep the air FORCED and flowing through it.
Barry
On Thu, Jul 12, 2012 at 11:01 PM, AirEupora <AirEupora(at)sbcglobal.net (AirEupora(at)sbcglobal.net)> wrote:
[quote]--> JabiruEngine-List message posted by: "AirEupora" <AirEupora(at)sbcglobal.net (AirEupora(at)sbcglobal.net)>
High cylinder temps and propeller pitch?
Today, I got the first good flight out of my Europa with the Jabiru 3300L. This is the seventh flight and I only have two hours on the engine. I have been chasing high cylinders temp and high oil temps. I'm getting close to having the oil temps under control. Most of it is getting the opening around the oil cooler correct. Right now 4 & 6 are running high CHT at full power. I'm only getting about two to three minutes of operation at these power settings. The RPM is starting to come up and I got 2900 for almost a minute.
EGT's are within 50 degrees of each other. I have a stock needle and seat. Not sure what the numbers are.
The reason I'm asking is I had a Navion and the prop company pitch it too high and my CHT were to high. Once I had it re-pitched the CHT came down and the oil temp came down.
I'm thinking I should do the same for this engine. Decrease the pitch on the ground adjustable prop.
Does anybody have any ideals or suggestion?
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=378164#378164
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AirEupora
Joined: 01 Nov 2009 Posts: 186 Location: Dixon, CA
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Posted: Mon Jul 16, 2012 5:55 am Post subject: Re: What is the relationship between |
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Thanks Barry Check 6,
I hope I'm not to much of a Mystery Man. I'm an 68 year old retire(semi-retire pilot/mechanic) working on my Europa with a 3300L Jabiru. First flight was June 8, 2012. It only lasted six minutes because of high temp on all the cylinders. I have been working to get them all down and finally made a flight last Monday of 46 minutes. Four and Six were still running hot, but reducing power kept them from going near red line. Oil temps started coming up as the air temp at my altitude were 85. DA was about 1200 feet.
I rechecked my blade pitch and it was 20 degrees. I re-set it to 18.2. I have been working on the lower cowl to seal the oil cooler off. Should have that completed today. On my sixth flight of 30 minutes the oil temps were good, but the cowling had dropped down and when I found the reason and fixed it it opened the area in front of the oil cooler and on the next flight the temp slowly came up. Hopefully, I have fixed this problem.
Thanks to all on this web site as I have been reading your problems and remarks for the last year. I hope to learn something everyday.
Rick Stockton
N120EJ
Jabiru 3300L
Whirlwind Ground adjustable
Dixon, CA
KDWA
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