Interesting Oil Cooler Observations

[Sonerai13]

Mike,

To my knowledge there have never been any specific experiments regarding cooling outlet size on the Sonex cowl. Since all the factory airplanes are prototypes, no two are exactly alike. However, I have measured the cooling outlets on all the factory cowls and the outlet openings are all at least 125% of the inlet area. Some are a bit larger than that. They all work well though, so I'd say that so long as you have at least 125% or more you should be in good shape.


Joe
"Fortes Fortuna Adiuvat"

[MichaelFarley56]

Thanks for the info Joe. I think I flew my Waiex around 3 hours before I enlarged my exit area and haven't had an issue since. Even in the summer time things are great! On the last flight I had, the surface temperatures were in the upper 40's and my hottest cylinder got to around 360 in the climb, and leveled off around 310 in cruise. Not as good as the factory Waiex but I'll take it! I still owe Kerry a nice adult BEvERage someday for telling me to richen up my mixture last Oshkosh. I now aim for having my EGT's around 1200 on climbout, and things run nice and cool.

Thanks again!

[jgpainter2]

Hello all - Regarding Joe's comment about exit size in the cowling needing to be 125% of inlet size- Assuming a cowling built to plans and as supplied by Sonex, anyone know what the inlet size is in square inches? I'm too stupid to figure this out. George N1020X.

[MichaelFarley56]

Don't quote me for certain George, but I think each opening is around 6" x 4", so you're looking at close to 50 sq/in total cowling inlet area.

[Sonerai13]

On the Sonex cowl the two main openings total roughly 30 square inches of inlet area. If you have the little "mouth" below the prop to feed a bottom-mount oil cooler (or to just duct air across the bottom of the oil sump) you add about another 7 square inches.