---------------------------------------------------------- JabiruEngine-List Digest Archive --- Total Messages Posted Sun 04/20/08: 2 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 09:47 AM - Re: Re: EGTs and fuel quality (Andy Silvester) 2. 11:30 AM - Re: Re: EGTs and fuel quality (Lynn Matteson) ________________________________ Message 1 _____________________________________ Time: 09:47:44 AM PST US From: "Andy Silvester" Subject: RE: JabiruEngine-List: Re: EGTs and fuel quality Lynn, Good work on the improvements! I'm sure many of us have found the same situation of not knowing *exactly* what brings better performance, especially when we are talking about a few % only, but those RPM increases are significant. A note about SCEET ducting; I've used it with success on the intake. Someone once told me that SCAT ducting has an equivalent resistance of 23, meaning that 1 foot of SCAT ducting has the same resistance to airflow as 23 feet of smooth-bore pipe! SCEET will be better, but bear in mind one down-side which I'm sure won't affect you. The inner 'skin' of the duct can perish and suck flat if given enough time and bad maintenance. It's a fair point, and a few A&Ps have told me it's a no-no to use it on anything below ambient pressure, i.e. a carburettor intake. My response (while being sympathetic to the argument) was that most Experimental aircraft get better maintenance than certificated types(!) and therefore the idea of a piece of duct not being internally inspected for (say) 5 years or more is less likely in our world (.....or is it??!!) Keep up the good work, Andy -----Original Message----- From: owner-jabiruengine-list-server@matronics.com [mailto:owner-jabiruengine-list-server@matronics.com] On Behalf Of Lynn Matteson Sent: 19 April 2008 14:36 Subject: Re: JabiruEngine-List: Re: EGTs and fuel quality Chuck- I just flew my newly-modified and installed air duct (from airbox to carb) and it works fine. I'd say great, but it didn't even out the EGT's like I hoped, but it did *seem* to give me more WOT rpm. Of course the weather has changed since I last checked for WOT rpm, but before I'd have to point the nose down just a little to get 3000 rpm. Today I could fly level and get 3130 rpm. Again, the air density might have something to do with it. I'm also climbing out at about 90-100 rpm higher. It's a bitch to take down performance figures in the cold air, and by the time the changes are made, the weather does an "about face," and you have squat to compare to. Suffice it to say, the engine runs good now, so be it air-straightening vanes or better weather, I'm happy. One other thing I'm going to try...just for kicks...is to swap the SCAT hose for some SCEET hose from airbox to the vaned air duct. I just saw some SCEET hose, and that stuff is smooth inside! For just a few bucks more per foot, I'm going for it. After the initial flight today, I also changed to a 2.78 needle jet, up from the original 2.76 jet. (I had done this a few weeks ago, but changed float level too, and the combo had the engine stumbling, so I removed it at the time) That didn't change the EGT's all that much, but it did chase the hot EGT from #4 over to #3. I wasn't in the mood to write down a bunch of figures at the time, but I will, and report what I find. My carb had the 2005 Economy Kit on board when I bought it, and the jet and needle sizes were etched on the side of the carb. My needle number ended in -1, meaning one groove, as I understand it, and indeed it was a one-groove needle. Lynn Matteson Grass Lake, Michigan Kitfox IV Speedster w/Jabiru 2200 flying w/490+ hrs ________________________________ Message 2 _____________________________________ Time: 11:30:49 AM PST US From: Lynn Matteson Subject: Re: JabiruEngine-List: Re: EGTs and fuel quality Thanks for the input, Andy....I sure didn't know about, or probably would not have thought about, the inner skin sucking in, but it makes sense. I'll give that one some thought, but like you said, maintain it and it'll probably be OK. Lynn Matteson Grass Lake, Michigan Kitfox IV Speedster w/Jabiru 2200 flying w/490+ hrs On Apr 20, 2008, at 12:43 PM, Andy Silvester wrote: > > > Lynn, > > Good work on the improvements! I'm sure many of us have found the same > situation of not knowing *exactly* what brings better performance, > especially when we are talking about a few % only, but those RPM > increases > are significant. A note about SCEET ducting; I've used it with > success on > the intake. Someone once told me that SCAT ducting has an equivalent > resistance of 23, meaning that 1 foot of SCAT ducting has the same > resistance to airflow as 23 feet of smooth-bore pipe! SCEET will be > better, > but bear in mind one down-side which I'm sure won't affect you. The > inner > 'skin' of the duct can perish and suck flat if given enough time > and bad > maintenance. It's a fair point, and a few A&Ps have told me it's a > no-no to > use it on anything below ambient pressure, i.e. a carburettor > intake. My > response (while being sympathetic to the argument) was that most > Experimental aircraft get better maintenance than certificated types > (!) and > therefore the idea of a piece of duct not being internally > inspected for > (say) 5 years or more is less likely in our world (.....or is it??!!) > > Keep up the good work, Andy > > -----Original Message----- > From: owner-jabiruengine-list-server@matronics.com > [mailto:owner-jabiruengine-list-server@matronics.com] On Behalf Of > Lynn > Matteson > Sent: 19 April 2008 14:36 > To: jabiruengine-list@matronics.com > Subject: Re: JabiruEngine-List: Re: EGTs and fuel quality > > > > Chuck- > I just flew my newly-modified and installed air duct (from airbox to > carb) and it works fine. I'd say great, but it didn't even out the > EGT's like I hoped, but it did *seem* to give me more WOT rpm. Of > course the weather has changed since I last checked for WOT rpm, but > before I'd have to point the nose down just a little to get 3000 rpm. > Today I could fly level and get 3130 rpm. Again, the air density > might have something to do with it. I'm also climbing out at about > 90-100 rpm higher. It's a bitch to take down performance figures in > the cold air, and by the time the changes are made, the weather does > an "about face," and you have squat to compare to. Suffice it to say, > the engine runs good now, so be it air-straightening vanes or better > weather, I'm happy. One other thing I'm going to try...just for > kicks...is to swap the SCAT hose for some SCEET hose from airbox to > the vaned air duct. I just saw some SCEET hose, and that stuff is > smooth inside! For just a few bucks more per foot, I'm going for it. > > After the initial flight today, I also changed to a 2.78 needle jet, > up from the original 2.76 jet. (I had done this a few weeks ago, but > changed float level too, and the combo had the engine stumbling, so I > removed it at the time) That didn't change the EGT's all that much, > but it did chase the hot EGT from #4 over to #3. I wasn't in the mood > to write down a bunch of figures at the time, but I will, and report > what I find. > > My carb had the 2005 Economy Kit on board when I bought it, and the > jet and needle sizes were etched on the side of the carb. My needle > number ended in -1, meaning one groove, as I understand it, and > indeed it was a one-groove needle. > > Lynn Matteson > Grass Lake, Michigan > Kitfox IV Speedster w/Jabiru 2200 > flying w/490+ hrs > > ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message jabiruengine-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/JabiruEngine-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/jabiruengine-list Browse Digests http://www.matronics.com/digest/jabiruengine-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.