Grob G109 Cooling Modifications
In Australian conditions, the standard G109 Limbach motor tends to run
very hot. The modifications outlined below solve that problem.
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This image shows the extended oil pickup, made from gas fittings.
Not obvious in the photo are the transverse holes near the base of the
pickup. These are essential. |
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Note the 6 studs - these need special attention to prevent oil leaks
and loosening during servicing.
Using allen bolts lockwired in place will probably work. |
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The finished sump - note the mod to the heat exchanger. |
This GFA approved modification, in addition to a NACA duct in the top
cowl feeding directly to the oil cooler which has been exchanged for a
deeper Kombi unit, along with Penrite 25/70 oil, has resulted in greatly
increased cooling efficiency. As this aircraft (FFN) is often flown in
extreme outback Australian conditions, the difference in performance has
been remarkable. For instance, getting out of Longreach at midday in summertime
usually involved creeping off the runway and sneaking up the highway at
uncomfortably low altitude until we struck a thermal, as the oil temp would
have hit the limit before we could climb to a thousand feet. Now we can
just leave it in fine pitch and climb at near full throttle to 5000!
Another modification which has been most beneficial is the addition
of dual ignition.
