---------------------------------------------------------- RV-List Digest Archive --- Total Messages Posted Sat 06/11/11: 7 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 12:38 PM - Re: RV6A CHT Problem (Jack Haviland) 2. 02:46 PM - Re: RV6A CHT Problem (Kelly McMullen) 3. 02:59 PM - Re: RV6A CHT Problem (vanremog) 4. 04:56 PM - Re: RV6A CHT Problem (Jack Haviland) 5. 07:07 PM - Re: RV6A CHT Problem (Denis Walsh) 6. 08:35 PM - Re: sudden high temps (mr.gsun@gmail.com) 7. 08:36 PM - Re: RV6A CHT Problem (Kelly McMullen) ________________________________ Message 1 _____________________________________ Time: 12:38:34 PM PST US Subject: Re: RV-List: RV6A CHT Problem From: Jack Haviland A 20 to 3- degree drop from putting the wheel pants and strut fairing on would make an enormous difference! I never would have predicted a decrease of more than a few degrees but I'm going to put them on and try it. Almost all of the baffling and carb linkage related suggestions have previously been investigated and judged acceptable. I'll also obtain a richer carburetor jet (rather than drilling one out with number drills on a lathe) as soon as I can find one. One last question on that topic. Is a "full-rich to first-cylinder-to lean EGT differential less than 150 degrees F.'" really a "recognized" way of detecting lean carburetor jetting? The Lycoming representative said he had never heard of it but I found references to it during web searches and talking to two engine rebuilders. Thanks for all the help! It is very much appreciated. jack On Jun 10, 2011, at 8:46 AM, Kelly McMullen wrote: > If you don't have wheel pants/fairings on, the engine will run hotter, probably 20-30 degrees. ________________________________ Message 2 _____________________________________ Time: 02:46:00 PM PST US From: Kelly McMullen Subject: Re: RV-List: RV6A CHT Problem On takeoff from a sea level airport the EGT should be 150 to 200 degrees less than a normal peak EGT. 1200-1300 on most engines is a safe takeoff EGT. You don't want to see much over 1300. But keep in mind the power enrichment circuit is supplying maybe 1/3 of that extra richness, so you won't see that big a spread from full rich in cruise with less than full throttle to peak in cruise. Probably more like 100 degrees generated by the mixture control. On 6/11/2011 12:34 PM, Jack Haviland wrote: > --> RV-List message posted by: Jack Haviland > > To: Kelly and All Others Who Were Kind Enough to Provide Helpful Comments, > > A 20 to 3- degree drop from putting the wheel pants and strut fairing on would make an enormous difference! I never would have predicted a decrease of more than a few degrees but I'm going to put them on and try it. Almost all of the baffling and carb linkage related suggestions have previously been investigated and judged acceptable. > > I'll also obtain a richer carburetor jet (rather than drilling one out with number drills on a lathe) as soon as I can find one. One last question on that topic. Is a "full-rich to first-cylinder-to lean EGT differential less than 150 degrees F.'" really a "recognized" way of detecting lean carburetor jetting? The Lycoming representative said he had never heard of it but I found references to it during web searches and talking to two engine rebuilders. > > Thanks for all the help! It is very much appreciated. > > jack > On Jun 10, 2011, at 8:46 AM, Kelly McMullen wrote: > >> If you don't have wheel pants/fairings on, the engine will run hotter, probably 20-30 degrees. > > ________________________________ Message 3 _____________________________________ Time: 02:59:36 PM PST US From: vanremog Subject: Re: RV-List: RV6A CHT Problem Best way in my opinion, to verify that you have the correct main jet, is to confirm max fuel flow at WOT as you are climbing out full rich flat pitch max rpm as near MSL as possible. Do you have an engine monitor that logs fuel flow? If so, then you can confirm this with the formula (0.48 * maxhp)/6 = fuel flow at WOT. For example this would be approx 14.4 gph with a 180 hp aircraft engine. Until you get this, you are not flowing enough fuel. Then work from there as needed with your oil cooler, intakes, exit and baffling to maximize the cooling effects for your installation. -GV (RV-6A N1GV flying 972hrs) In a message dated 06/11/11 12:39:12 Pacific Daylight Time, jgh2@charter.net writes: A 20 to 3- degree drop from putting the wheel pants and strut fairing on would make an enormous difference! I never would have predicted a decrease of more than a few degrees but I'm going to put them on and try it. Almost all of the baffling and carb linkage related suggestions have previously been investigated and judged acceptable. I'll also obtain a richer carburetor jet (rather than drilling one out with number drills on a lathe) as soon as I can find one. One last question on that topic. Is a "full-rich to first-cylinder-to lean EGT differential less than 150 degrees F.'" really a "recognized" way of detecting lean carburetor jetting? The Lycoming representative said he had never heard of it but I found references to it during web searches and talking to two engine rebuilders. Thanks for all the help! It is very much appreciated. jack On Jun 10, 2011, at 8:46 AM, Kelly McMullen wrote: > If you don't have wheel pants/fairings on, the engine will run hotter, probably 20-30 degrees. ________________________________ Message 4 _____________________________________ Time: 04:56:11 PM PST US From: Jack Haviland Subject: Re: RV-List: RV6A CHT Problem On Jun 11, 2011, at 5:56 PM, vanremog wrote: > Do you have an engine monitor that logs fuel flow? Unfortunately I elected not to install a fuel flow sensor - an error I'm regretting. > 1200-1300 on most engines is a safe takeoff EGT. You don't want to see much over 1300. One more thing to worry about! My EGTs at full power typically run around 1350 to 1375 F. I had attributed that to the sensors being installed only about 2.25" from the exhaust flange. I'm also considering the suggestion to deliberately retard the mag timing slightly. Thanks again for the advice. I'll post my findings after making some progress on the problem jack ________________________________ Message 5 _____________________________________ Time: 07:07:08 PM PST US Subject: Re: RV-List: RV6A CHT Problem From: Denis Walsh On Jun 11, 2011, at 3:56 PM, vanremog wrote: > Best way in my opinion, to verify that you have the correct main jet, is to confirm max fuel flow at WOT as you are climbing out full rich flat pitch max rpm as near MSL as possible. Do you have an engine monitor that logs fuel flow? > > If so, then you can confirm this with the formula (0.48 * maxhp)/6 = fuel flow at WOT. For example this would be approx 14.4 gph with a 180 hp aircraft engine. Until you get this, you are not flowing enough fuel. > > Then work from there as needed with your oil cooler, intakes, exit and baffling to maximize the cooling effects for your installation. > > -GV (RV-6A N1GV flying 972hrs) > > > > > > In a message dated 06/11/11 12:39:12 Pacific Daylight Time, jgh2@charter.net writes: > > To: Kelly and All Others Who Were Kind Enough to Provide Helpful Comments, > > A 20 to 3- degree drop from putting the wheel pants and strut fairing on would make an enormous difference! I never would have predicted a decrease of more than a few degrees but I'm going to put them on and try it. Almost all of the baffling and carb linkage related suggestions have previously been investigated and judged acceptable. > > I'll also obtain a richer carburetor jet (rather than drilling one out with number drills on a lathe) as soon as I can find one. One last question on that topic. Is a "full-rich to first-cylinder-to lean EGT differential less than 150 degrees F.'" really a "recognized" way of detecting lean carburetor jetting? The Lycoming representative said he had never heard of it but I found references to it during web searches and talking to two engine rebuilders. > > Thanks for all t > > > > ________________________________ Message 6 _____________________________________ Time: 08:35:48 PM PST US Subject: Re: RV-List: sudden high temps From: mr.gsun@gmail.com How about a brass brush from your rifle cleaning kit. You can get various sizes and use enough lengths of cleaning rod to get down where you want to be. I suppose you could even repaint down in there with the cotton swabs that also attach to the rods. Do not archive Greg On Jun 10, 2011 8:48 AM, "Dale Ensing" wrote: > If I remember correctly Tom, I purchased them at a tobacco/pipe shop. > Dale > > ----- Original Message ----- > From: thomas sargent > To: rv-list@matronics.com > Sent: Friday, June 10, 2011 9:52 AM > Subject: Re: RV-List: sudden high temps > > > Dale: > > > That sounds interesting. Can you suggest where I might get such a thing? > > > On Fri, Jun 10, 2011 at 2:57 AM, Dale Ensing wrote: > > You can buy pipe cleaners that have small wire bristles mixed in with the soft fibers. Might be worth a try. > > > -- > Tom Sargent > > ________________________________ Message 7 _____________________________________ Time: 08:36:07 PM PST US From: Kelly McMullen Subject: Re: RV-List: RV6A CHT Problem That is too hot for full power EGT. You need more fuel flow. My probes are 1.5" from exhaust flange and I keep rich enough for 1325 or less on takeoff, normally closer to 1250. On 6/11/2011 4:52 PM, Jack Haviland wrote: > > On Jun 11, 2011, at 5:56 PM, vanremog wrote: > >> Do you have an engine monitor that logs fuel flow? > Unfortunately I elected not to install a fuel flow sensor - an error > I'm regretting. > > > 1200-1300 on most engines is a safe takeoff EGT. You don't want to > see much over 1300. > One more thing to worry about! My EGTs at full power typically run > around 1350 to 1375 F. > I had attributed that to the sensors being installed only about 2.25" > from the exhaust flange. > > I'm also considering the suggestion to deliberately retard the mag > timing slightly. > > Thanks again for the advice. I'll post my findings after making some > progress on the problem > jack > > > * > > > * ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message rv-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/RV-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/rv-list Browse Digests http://www.matronics.com/digest/rv-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.