Today's Message Index:
----------------------
1. 01:44 AM - Re: CHT temp and ram air duct question (FLYaDIVE)
2. 02:07 AM - Re: What is the relationship between (FLYaDIVE)
3. 04:57 AM - Re: CHT temp and ram air duct question (Mark Hubelbank)
4. 09:52 AM - Re: CHT temp and ram air duct question (DaveG601XL)
5. 02:38 PM - CHT's (BobbyPaulk@comcast.net)
Message 1
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| Subject: | Re: CHT temp and ram air duct question |
Jeffery:
Years back I was working on an RV6 that had CHT issues. The baffling was
perfect and I could not get the Temps down. Then I looked at a different
RV6 and I notice - WOW - Did I notice something different with the inlet
ducts. The builder FAILED to install two small pieces of fiberglass that
should have been glassed to the TOP of the cowling right behind the inlet.
They were as wide as the inlet - they moved back about 3" and then
smoothly curved up to the top of the cowl. This sounds confusing, but
think of it like an inverted wing attached to the INSIDE - Upper cowl. I
found the parts in his junk box - Installed them and WOW! The temps
dropped like crazy.
You could go to the RV website and order the fiberglass and give it a try.
Barry
On Thu, Jul 12, 2012 at 5:36 PM, Jeffrey J Paris <jeffrey-j-paris@excite.com
> wrote:
> Dear List,
>
> I am runnning a Jab 3300 on a Zenith CH601XLB experimental that I built.
> The last few years I have been doing my best to get control and manage the
> cooling of my CHT's. I'm am getting real close to pretty good temps with
> the addition of some baffles in my ram air ducts. Before the baffles my #4
> cylinder ran hottest, now that I have that under control my #5 and #6
> cylinders are running as hottest almost neck to neck. Without going into
> great detail, I am wondering what is the best action to take with what I
> assume will be to trim the inner ram airduct baffling to increase airflow
> to these cylinders without hurting the airflow on cylindeers #3 & #4.
>
> Do I work front to back, or back to front and how much do I take off?
> Thanks for your time and consideration.
>
> Jeff Paris 2 Jabs one in a Zentith the other in a Europa. Rochester NY
>
>
> *
>
> *
>
>
Message 2
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| Subject: | Re: What is the relationship between |
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@sbcglobal.net> wrote:
> AirEupora@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
>
>
Message 3
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| Subject: | Re: CHT temp and ram air duct question |
Barry,
Although in the wonderful and seemingly unpredictable world of
Jabiru cooling, I have improved cooling of my 3300 by removing baffles,
this sounds interesting, I could not find the picture or part, could you
post a link.
Mark Hubelbank
Ch601XL-B
Jabiru 3300
Sensenich adj prop
Rotec TBI-40-3
240 Hours airframe
On 07/13/2012 4:43 AM, FLYaDIVE wrote:
> Jeffery:
>
> Years back I was working on an RV6 that had CHT issues.
> The baffling was perfect and I could not get the Temps down. Then I
> looked at a different RV6 and I notice - WOW - Did I notice something
> different with the inlet ducts. The builder FAILED to install two
> small pieces of fiberglass that should have been glassed to the TOP of
> the cowling right behind the inlet. They were as wide as the inlet -
> they moved back about 3" and then smoothly curved up to the top of the
> cowl. This sounds confusing, but think of it like an inverted wing
> attached to the INSIDE - Upper cowl. I found the parts in his junk
> box - Installed them and WOW! The temps dropped like crazy.
>
> You could go to the RV website and order the fiberglass and give it a try.
>
> Barry
>
> On Thu, Jul 12, 2012 at 5:36 PM, Jeffrey J Paris
> <jeffrey-j-paris@excite.com <mailto:jeffrey-j-paris@excite.com>> wrote:
>
> Dear List,
> I am runnning a Jab 3300 on a Zenith CH601XLB experimental that I
> built. The last few years I have been doing my best to get
> control and manage the cooling of my CHT's. I'm am getting real
> close to pretty good temps with the addition of some baffles in my
> ram air ducts. Before the baffles my #4 cylinder ran hottest, now
> that I have that under control my #5 and #6 cylinders are running
> as hottest almost neck to neck. Without going into great detail,
> I am wondering what is the best action to take with what I assume
> will be to trim the inner ram airduct baffling to increase airflow
> to these cylinders without hurting the airflow on cylindeers #3 & #4.
> Do I work front to back, or back to front and how much do I take
> off? Thanks for your time and consideration.
> Jeff Paris 2 Jabs one in a Zentith the other in a Europa.
> Rochester NY
>
Message 4
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| Subject: | Re: CHT temp and ram air duct question |
Jeff,
What kinds of CHT's are you seeing between climb and cruise? I can understand
why #5 and #6 are the hottest, but are they too hot? No sense in chasing something
if it is in limits.
I guess I was lucky that my CHT's were never really that close to or over the limits
during phase 1. After break-in, when they dropped off a bit, I did some
tweaking to get even more margin. Then I stopped playing with it and concentrated
on my EGT for a while. Now I just fly and review my EMS data every month
or so.
Good luck,
--------
David Gallagher
Zodiac 601 XL-B: flying, 220+ hours now
Next project under construction: Finish my father's Aircamper
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=378203#378203
Message 5
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List
I also have had serious problems getting the CHT's to a usable range. I finally
got 1 thru 5 down below 300 deg but #6 is hotter running 310 ~ 320.
i have increased the height of the ram air ducts since I had the older style ducts
with the plug wires on the outside. ( they are now on the inside ). I also
installed baffles or dams and ground off an 1/8" at a time until I got them as
good as they are going to get with this set up. . My question is what is a SAFE
continuous CHT temp. The book says 354 MAX continuous and I know that cooler
is better to a point. Is 320 continuous safe??
I am using a 51" pitch Sensenich prop which was recommended along with the 49".
The temps are very sensitive to manifold pressure as the slide in the Constant
Velocity Carb is always moving with the differential pressure. The 51" pitched
prop may be drawing too much manifold pressure at a given RPM. I believe it
to be a good match since it will turn 3350 in straight and level flight. BUT
it will only turn 2350 static.
At reduced RPM ( 2200 ) all cylinders will be below 300.
I am going to try raising the lower baffle on #2 cyl as recommended by Paul. In
theory that should reduce the flow and drop the pressure downstream ( as he said
- "makes no sense" ). But worth a try at this point.
By the way - A friend has the new cowl with larger inlets ( from Pete ) and has
had NO problems with temps.
Bobby ( age 74 )
Zodiac 601 XL "B"
Jabiru 3300 S/N 1141
Sensenich 64" x 51" Prop
Bing Carb 260 Main & 285 Needle Jet
Status - Flying 156 hrs.
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