Hi Matt, your coolers seem to be sized and proportioned okay but 2.5" air feed into your oil cooler is optimistic - your inlet is 12 sq in - if you increased your SCAT from 2.5" to 4" that will get all your inlet air to the oil cooler - even that may be too small. The Mazda is 2/3 water-cooled and 1/3 oil-cooled, so in general terms your radiator should be about twice the size of your oil cooler and the ducts with similar proportions.
Jeff


I'm having a hard time in this Florida heat, trying to do my first flight. With a highspeed taxi run, (up to 55kts or so), will net my oil and coolant above my warning limits. 240 oil pan, 230 coolant out.

The coolant inlet (44sq") is huge with the idea that down the road I'd go turbo. The rad is from a dodge truck 19 x 24 x 1 = 454sq", with a wedge shape diffuser. Right now it just exits the back of the cowl, no cowl flaps or sub cowl installed yet.

The oil inlet is a lot smaller (~12.5sq"), going to a 2.5" scat hose, then to a trumpet shape which leads into a wedge. The oil rad is 9 x 11 x 2 = 198sq" from cx racing. For the outlet, I have a big box to collect the hot/expanded air, then neck it back down to 2.5" exit. Tomorrow I'll try another taxi test, with the outlet box completely removed and dumping into the cowl.

To find out if my prop is doing anything with airflow into the inlets, used a tube of water and found around 2200 static rpm, it raised the water about 4inches in the oil duct. I think that equals around ~55kts. I thought the prop would of cooled down the rads a lot more, but I guess I have bad duct designs. Maybe move them closer to the blade? Looking at the picture, the oil is on the left with all the green tape. I tried to make the opening bigger with foam, didn't see a real difference. Being on the bottom of the cowl and to the left, it doesn't get the rotating air from the blades as much.

I know high speed taxi tests in this Florida heat, is probably the worst case scenario. Depending how the morning goes, we might just fly the plane and get some speed into her nose. See at what speed the temperatures stabilize and start to cool down.

- Matt Boiteau
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