---------------------------------------------------------- JabiruEngine-List Digest Archive --- Total Messages Posted Fri 07/13/12: 5 ---------------------------------------------------------- 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 _____________________________________ Time: 01:44:21 AM PST US Subject: Re: JabiruEngine-List: CHT temp and ram air duct question From: FLYaDIVE 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 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 _____________________________________ Time: 02:07:55 AM PST US Subject: Re: JabiruEngine-List: What is the relationship between From: FLYaDIVE 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 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 _____________________________________ Time: 04:57:38 AM PST US From: Mark Hubelbank Subject: Re: JabiruEngine-List: 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 > > 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 _____________________________________ Time: 09:52:25 AM PST US Subject: JabiruEngine-List: Re: CHT temp and ram air duct question From: "DaveG601XL" 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 _____________________________________ Time: 02:38:50 PM PST US From: BobbyPaulk@comcast.net Subject: JabiruEngine-List: CHT's 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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