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Permalink Reply by Jim and Amelia Isaacs on April 4, 2024 at 4:21pm

I don’t think it matters at all, but if you decide to seal them use something soft and flexible- if the cowling is directly touching the radiator the vibration will damage either the radiator mount bracket or the cowling, or possibly both. My 701 has the Zenith FWF kit and the oil cooler is mounted just forward of the firewall.  I removed the kit-supplied ductwork and scat tube that was directing ducted ram air to the oil cooler because my 912 UL just wouldn’t reach the 212 degree Fahrenheit target temp Rotax wants for every flight. I never saw oil temps above 180 or so even in the Summer. I still must add a strip of aluminum tape across the top row of oil cooler fins in the winter or she still wouldn’t reach 212 degrees. My radiator is mounted up front under the cowl and has a 1/4” gap to prevent cowl-radiator contact and my coolant temp stays middle of the green arc even in Summer. So in my configuration, sealing the coolers to the cowl to force maximum airflow through them would actually be a bit counterproductive in reaching the desired operating temps. Your configuration will guide you during test flights- perhaps start without sealing and fly it, if temps dictate, add the seals?

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Permalink Reply by Jack E Martin on April 5, 2024 at 10:31am

Thanks for the good information.

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