Thanks to all of you have gave excellent ideas and suggestions, my oil temperature problem has been completely solved.

 

At first, I mounted my oil cooler to the firewall and ran a 3 inch SCAT off Cylinder 4 but the SCAT came right off the fins so it was getting hot air.  Oil temps here ran 230-240F - too hot for me.

 

Then, I left the oil cooler on the firewall and cut a NACA duct into the passenger side of the cowl and ran a 5 foot long NACA duct to the cooler.  This helped but oil temps were still around 220F.  I then built a custom air exit for the oil cooler and installed shark fins to exit the air.  This would be a completly sealed system for the oil cooler and I thought the shark fins would create a vacuum to help the air exit allowing more air to enter but this mod did not change the oil temps any lower than 220F.    I glassed over the passenger side NACA inlet.

 

Third, I moved the NACA duct inlet to the pilot's side and moved it lower on the cowl.  As low as I could without getting too close to the exhaust.  I felt more air runs lower than on the side of the cowl.   I ran a 3 inch SCAT tube up and over the engine mount which was still on the firewall.  This was still a completely sealed system and I thought this would be the big fix since the air had less tubing to travel to get to the oil cooler.  This did NOT work because of the loop of the SCAT tube going over the engine mount.  Air went in the NACA inlet just fine but did not want to go around the bend and into the oil cooler.  I think a little tornado at the top of the bend just prevented air from going in.

 

So, I left the NACA inlet on the pilot's side as low as I could go toward the bottom of the cowl and I moved the oil cooler off the firewall.   I discarded the custom oil cooler exit tunnel I made.   The oil cooler is now mounted to the engine mount and to the firewall with some clamps on the top of the oil cooler and some custom RV builder designed brackets on the bottom from my brother Danny who is building his RV in his basement with no way to get it out.  We will have to dig a big hole and knock a few blocks out in the next few months.  We are thinking of sending his wife to a far away place for that.    But you know builders - that's not something we have to deal with till we have to deal with it.

 

So, the oil cooler is now mounted from the engine mount and the firewall but it lines up perfectly with the NACA inlet and uses a 4 inch long piece of 3 inch SCAT.   THIS WORKS PEFECTLY !!!!!   When you look up the NACA inlet, you can see the fins of the oil cooler.  You cannot make the air happier than that.  In fact, it almost works TOO good.  Oil temps now are running 180-190F at 75F OAT.   Before winter, I will add the Van's aircraft oil cooler exit restrictor they sell for $85.

 

I cannot tell you how thankful I am of all the input and how happy I was to learn and try new things and experiment.  I am thankful my plane is just in primer and not paint because I would have screwed up and nice paint job for sure.  Now I know what works.

 

I have a Stewart Warner 9 vane oil cooler and it works perfectly.    I left the shark fins because both of my exhaust pipes exit on the pilot side and this helps.  Also, the oil cooler air exit just exits into the lower engine cowl area.   There is no custom exit on the cooler.    It works now so I'm not going to touch it.

 

Here is a couple pix of the solution:

 

 

 

 

 

I hope this helps some of you or gives you some ideas.

 

Matt Reeves

Rochester, NY