IFLYSMODEL(at)AOL.COM
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 Posted: Sat Jul 09, 2011 1:59 am Post subject: engine power loss |
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Hey Nick: I found Pete's info about the recommended Jabiru power/rpm/settings. It seems straight forward when you have an engine operating correctly. Since mine still does not, what do we do?
Pete's info >>> This is really quite simple. We've built over 200 planes here at Jabiru USA
| Quote: | with Jabiru engines. Each airframe / engine combination needs to have the
carb tuned to the airframe drag and prop load that will be placed on the
engine. First - climb out at full throttle at normal climb attitude and
observe the EGT during climb. The center of the spread should be 1225 F.
If lower then change to a smaller main jet. If higher change to a larger
main jet.
Then level off for cruise at normal cruise rpm - 2850 for the 3300 and 2900
- 2950 for the 2200. Observe EGT's. Center of the range should be 1325.
If lower install smaller needle jet. If higher install larger needle jet.
This procedure works for us every time but there are a few requirements.
The prop that is installed must allow normal static rpm range of 2700 -
2800. We don't do a true static but take the runway and apply full throttle
and observe rpm before plane leaves the ground. We will not continue if rpm
is not at 2700 or more.
Finally - we compare right and left sides of engine for EGT. If one side is
hotter than the other we tilt the carb a few degrees with bottom toward the
hot side of the engine. Most every time this will even out temps after a
few flights of trial and error.
We've used this procedure on Jabiru Calypso's, J170's, SP's, J250's and
J230's as well as Rans S7 and S-19, Zenith CH601, CH701, Avids, Kitfox 4 &
7, Titan Tornado's, Kolb Mark III, and next week a Vans RV-12.
One necessary item for successful installation and adjustment is an engine
monitor that monitors all cylinders accurately. We think a GRT EIS is the
best instrument for accuracy and reliability but a few others are now
getting better. Most of our customers' engine problems come from
installations without sufficient monitoring. For instance - we have a 2200
in here now that broke a valve. There was no EGT instrument in the
airplane. The prop used was such a low pitch that it never loaded the
engine enough to make the carb deliver the right mixture but the operator
didn't have a clue of what was happening.
I don't obsess over charts or graphs - I just get the engines tuned to the
temp range specified in Jabiru's literature and for the most part have few
issues.
Pete Krotje
Jabiru USA Sport Aircraft, LLC
931-680-2800
www.usjabiru.com
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Still waiting answers
Lynn
[quote][b]
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