Final cooling solution for 583 liquid cooled Lycoming 583cu in engine on Gryphon

This represents the third complete redesign of the radiator installation and cooling air routing. The first install was a 15’x 15”x 1.5” core. The air came in through the original intakes and ran through the upper plenum to the rear of the engine. This disrupted air flow, heated air across engine, would only cool engine at about 60% power without water spray across radiator. I used this “bandaid” to get through 2023 races but this was obviously not a good long term solution! V2 was a much larger core (37” wide and 14” tall 3” thick) similar air passage across the engine but the huge radiator overheated on the ground while waiting for the oil temp to come up. I threw all that in the bin and went after the problem from scratch. The first step was to isolate the RH intake and build a closed passage down RH inside of the cowling that ramped slowly to the face of a 15 x 15” radiator core by 1.5” thick. This was the same size as V1. Additionally I was able to have a custom radiator built with all the sensor ports and hose attach fittings in locations to minimize the complexity of the installation. Next, I installed a thinner but larger area oil cooler similar to the same one installed on a Kitfox with Rotax and added a pretty large NACA-style intake on LH side that ramped smoothly to the face of cooler. I mounted the radiator and oil cooler to the sides of the engine mount at about a 45-degree angle to the front of the engine. This created a common area behind coolers that exited both through augmenters around exhaust exits and a small vent on top of the cowling to release heat on the ground. I will probably change this to an electric door that I can open as needed. Lastly, I tested leaving the LH intake open to let air just run around the engine and then closing it with a rounded cover. I expected closing it off would be better to lower pressure inside the cowling and to reduce overall drag, I was right.

I have about 10 flights with this setup and can now climb at 160 IAS to 11,000 feet without exceeding 225 degrees of coolant on a standard day. Oil temp reaches 220 but quickly reduces once leveled off. Oil runs around 200 degrees after about 10 minutes and the coolant seems to like 208-212. which the engine designer confirms is perfect.

I am now focusing on race altitudes and WOT test runs. Coolant can reach 230 WOT at about 230 IAS @5000 feet, oil temp stays well below 210 so I feel I am pretty good. I still need to dial up timing and clean up a few areas around intakes but I am very happy with the setup as is without the need for water cooling spray on the radiator. I am planning on competing in the first Sport Class Race outside Reno in Las Cruses Oct 17-21. I’ll update the experience on the course after the races are over. Wish me luck!