Oil cooler cowl inlet

[onex28]

For you builders completed and flying behind the Aerovee what is the optimum size cowl inlet opening for the oil cooler. I'm looking at something around 5 X 1 1/2 inches but don't know if that is too small, too large of about right.

David W

[Sonex1517]

Turbo or non turbo?

Top mount or bottom mount oil cooler?

When I made my Sonex cowling I built it per plans, but had a turbo with a top mounted oil cooler. I ended up taping over the oil cooler inlet for cooling purposes.

So the answer may depend on your configuration.

[onex28]

Robbie, it is a non turbo and bottom mounted cooler. Thanks.

David W

[wlarson861]

I used the dimensions called for in the plans when I first built the airplane with the bottom mount cooler and found it to be effective at cooling the oil. When flying below freezing temps it was too effective and fashioned a grill to cover the opening to cut down the amount of air and raise the oil temp some. If still building, I would go with the plans dimensions and see how well it works, understanding that a brand new engine will be hotter at first until well broken in. After moving to the turbo and top mount oil cooler I left the lower intake open to pass cooling air across the oil pan. The top mount was a bit cooler when normally aspirated but not drastically so. Turbo charged, the oil temps went up a little. Recently, with oat at altitude around 60 to 70 F the oil temps have been about 170 F. Well below the high limit.

[kevinh]

After moving to the turbo and top mount oil cooler I left the lower intake open to pass cooling air across the oil pan. The top mount was a bit cooler when normally aspirated but not drastically so. Turbo charged, the oil temps went up a little.

This may be off-base (because I haven't even finished my Waiex). But have you considered an experiment of taping up the bottom inlet? I wouldn't be surprised if the low cooling efficiency of air flowing along the oil pan is offset by decreasing the pressure difference between the top and the bottom of the cowl. If the bottom was closed it seems like there might be more cooling air flowing through the cylinders and the top cooler (and slightly less cooling drag).

[onex28]

I have a Onex but am using a bottom mounted oil cooler. I don't have Sonex plans but would like to know the Sonex dimensions for the cowling oil cooling inlet. Would appreciate someone posting that info. Thanks.

David W

[ScottM-Sonex1629]

It's not in the Sonex plans...

Look in the AeroVee assembly manual, Appendix A, page 66.

http://www.aeroconversions.com/support/ ... Manual.pdf

[Sonex1517]

No wonder I couldn't find it when I looked!

Scott is correct. It's on page 66 in that link.

[onex28]

Exactly what I need, thanks to all for your help.

David W

[wlarson861]

After moving to the turbo and top mount oil cooler I left the lower intake open to pass cooling air across the oil pan. The top mount was a bit cooler when normally aspirated but not drastically so. Turbo charged, the oil temps went up a little.

This may be off-base (because I haven't even finished my Waiex). But have you considered an experiment of taping up the bottom inlet? I wouldn't be surprised if the low cooling efficiency of air flowing along the oil pan is offset by decreasing the pressure difference between the top and the bottom of the cowl. If the bottom was closed it seems like there might be more cooling air flowing through the cylinders and the top cooler (and slightly less cooling drag).

I have not completely closed off the bottom opening but others have with mixed results. Some have had adequate oil temps, others had high oil temps. I put the grill I made on last summer and the oil temps went up, that is only about a 50% reduction to the opening. I took it off and haven't put it back on. I may see what it does in cooler weather but not now with the oats going up(finally).