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1. 10:27 AM - Re: Re: JabiruEngine-List Digest: 3 Msgs - 05/04/08 (Lynn Matteson)
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| Subject: | Re: JabiruEngine-List Digest: 3 Msgs - 05/04/08 |
Peter-
I envy you guys who have the room to build/install a plenum/manifold.
I do not, or I'd be doing it....I'd love to see yours when finished.
Lynn Matteson
Grass Lake, Michigan
Kitfox IV Speedster w/Jabiru 2200
flying w/503+ hrs
do not archive
On May 5, 2008, at 5:36 PM, Peter Harris wrote:
> Bob,
>
> I replaced the Bing with a simple throttle body and two injectors.
> I have a potentiometer to over ride the ECU if necessary and this
> was useful when fixing fuel maps . I am monitoring EGT at #5 and
> #6. With the present map settings I have even EGT (about 690degC)
> at TOC but if I leave the throttle open and accelerate I see EGT 5
> goes to 780degC ie almost 100 deg hotter, and the engine starts to
> shake because of uneven power strokes R to L.
>
> I think the problem is caused because there is no intake manifold,
> only a 1/2L collector. I am building a 3.5L induction manifold
> using 64MM tube fittings and will be able to report on that soon.
>
> Peter
>
>
> From: owner-jabiruengine-list-server@matronics.com [mailto:owner-
> jabiruengine-list-server@matronics.com] On Behalf Of BobsV35B@aol.com
> Sent: Tuesday, 6 May 2008 2:28 AM
> To: jabiruengine-list@matronics.com
> Subject: JabiruEngine-List: Re: JabiruEngine-List Digest: 3 Msgs -
> 05/04/08
>
>
> Good Morning Bob and All,
>
>
> The key point here is that the actual temperature means very little
> and there really is NO need for all of them to read the same. What
> we really want to know is how close the cylinder is running to a
> stoichiometric mixture. Peak EGT occurs close to that mixture.
>
>
> On the lean side of stoichiometric, the engine will run cooler and
> on the rich side of stoichiometric, the engine will also run cooler.
>
>
> Since there are so many variables introduced by probe placement and
> incidental airflow considerations, the actual temperature IS
> immaterial. What we need to do is slowly lean and see just where
> each cylinder peaks in relation to fuel flow. I see no way to do
> that exercise with Jabiru and it's BMW motorcycle BING carburetor.
>
>
> Cooling or insulating your Lycoming was just messing around. It did
> nothing to adjust the mixture and that is what is important.
>
>
> I sure wish someone would come up with a method whereby we could
> lean the Jabiru so as to determine just how well balanced the
> mixtures actually are.
>
>
> On your Lycoming, that is fairly easy to do IF you have a good all
> cylinder monitor and a very accurate electronic fuel flow unit.
>
>
> Happy Skies,
>
> Old Bob
> AKA
> Bob Siegfried
> Ancient Aviator
> 628 West 86th Street
> Downers Grove, IL 60516
> 630 985-8502
> Stearman N3977A
> Brookeridge Air Park LL22
>
>
> In a message dated 5/5/2008 10:11:36 A.M. Central Daylight Time,
> rtmarshall@gotsky.com writes:
>
> <rtmarshall@gotsky.com>
>
> Hello Jabiru users, On your Egt issues while not flying one,I have
> a lyc, I
> was having some of the same issues a while back and in particular on a
> cylinder that would not come up to within a few degrees of all the
> rest,
> even after changing the injector nozzle, it was way cold. the
> reason was,
> the cooling air going by the out side of the EGT probe, I wrapped
> the pipe
> down about six inches and the temp came up. ! IMHO and FWIW. Bob
>
>
> Wondering what's for Dinner Tonight? Get new twists on family
> favorites at AOL Food.
>
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