hgerhardt
Well Known Member
Years ago, after the original baffle-mounted SW 8406R oil cooler (OC) cracked the baffle a couple of times, the 2nd time also cracking a flange of the OC, I ‘upgraded’ to a remote-mounted SW 10599R fed by 4” SCAT into a little box plenum. That installation was hardly any better temp-wise than the original one, but passable except on very hot days. Well, decided to figure out how to improve on that.
Installed a pair of Bluetooth manometer probes and characterized first the upper/lower cowl deltaP, (7” WC at 155 KTAS) and then upper cowl/face of OC. Found the duct lost 3” WC, or almost half of available pressure! Wow, SCAT sucks. Measured the OC location-to-baffle relationship and designed new ducts with turning vanes and a bellmouth to be 3d printed from nylon-12 via HP MJF process.
Installed and flew with that and holy cow! I now have 0.85” OC duct deltaP, which is a huge improvement. According to the SW performance charts, that improvement ought to increase heat rejection from 350 to 420 BTU/min, or ~20% improvement. Hasn't been warm enough lately to really test the cooling improvement, but one thing is clear: the oil cools off significantly faster in descent than it did before. Also, #3 CHT is now ~10F cooler, despite stealing more of its cooling air. Apparently more air blowing over the tops of the fins helps.
![OC duct 2.jpg OC duct 2.jpg](https://vansairforce.net/data/attachments/2/2222-2a4997676a87dbe04437a2f9fb2ab881.jpg)
Installed a pair of Bluetooth manometer probes and characterized first the upper/lower cowl deltaP, (7” WC at 155 KTAS) and then upper cowl/face of OC. Found the duct lost 3” WC, or almost half of available pressure! Wow, SCAT sucks. Measured the OC location-to-baffle relationship and designed new ducts with turning vanes and a bellmouth to be 3d printed from nylon-12 via HP MJF process.
Installed and flew with that and holy cow! I now have 0.85” OC duct deltaP, which is a huge improvement. According to the SW performance charts, that improvement ought to increase heat rejection from 350 to 420 BTU/min, or ~20% improvement. Hasn't been warm enough lately to really test the cooling improvement, but one thing is clear: the oil cools off significantly faster in descent than it did before. Also, #3 CHT is now ~10F cooler, despite stealing more of its cooling air. Apparently more air blowing over the tops of the fins helps.
![OC duct 1.JPG OC duct 1.JPG](https://vansairforce.net/data/attachments/2/2220-694abc03208786e63c418fd81012cbd9.jpg)
![OC duct 2.jpg OC duct 2.jpg](https://vansairforce.net/data/attachments/2/2222-2a4997676a87dbe04437a2f9fb2ab881.jpg)