Geico266
Well Known Member
As I fly the -12 in the heat of the midwestern plains this summer I am beginning to see oil temps that are approaching concern at moderate to high engine RPMS. While never in the yellow or red these temps are around 230F. The Shell Oil lubrication engineers I’ve talked to say you can run the oil at these temps with no issues, and Rotax says these temps are fine, but I would like to see them lower. The purpose of this thread is to document oil temps in the RV-12 and "solutions" to reduce summer operating oil temps.
The first step was to take Scott's advice and take a real close look at the bottom cowl cooling plenum radiator seal. The theory is by keep the air pressure high in the cooling plenum this increases / maintains airflow through the oil cooler. Okay, that sounds good, so I “tighten it up a little” and added more weather stripping on the bottom. The results were measureable and it reduced the oil temps by about 4 degrees F, but I was looking for something better.
Before we get going with the mods here are the current numbers after additional weather stripping.
4,800 RPM, OAT 75F, Oil temps: 207F
5,000 RPM, OAT 75F, Oil temps: 212F
5,200 RPM, OAT 75F, Oil temps: 220F
5,400 RPM, OAT 75F, Oil temps: 230F
A theory I have is radiant heat from the muffler is diminishing the cooling capacity / efficiency of the oil cooler. The muffler is about 1 1/4” away from the oil cooler. As I understand it, and in talking with qualified engineers air flow does not reduce the effect radiant heat has on an object. I decided to add a fiberglass heat wrap barrier to the muffler.
The above picture shows the muffler proximity to the oil cooler.
Here are the results of the test after the heat barrier was installed.
4,800 RPM, OAT 75F, Oil temp: 195F
5,000 RPM, OAT 75F, Oil temp: 209F
5,200 RPM, OAT 75F, Oil temp: 215F
5,400 RPM, OAT 75F, Oil temp: 222F
5,400 RPM, OAT 85F, Oil temp: 230F
It appears I might be onto something here as the temps are definately lower with just a minimal amount of exhaust wrap. I will post the results of further Non-Van Aircraft Approved Tinkering. I would like to try a heat sheild, but getting to close to the oil cooler could only diminish the airflow. I can see some serious tinkering thinking is in the future!
Here is a link to the material used. http://www.aircraftspruce.com/catalog/eppages/graphblkwrap.php
Do not use a product like this http://www.jegs.com/i/Thermo Tec/893/16850/10002/-1?CT=999
as it will not take the 1100F as advertized. Ask me how I know.
Your mileage may very.
The first step was to take Scott's advice and take a real close look at the bottom cowl cooling plenum radiator seal. The theory is by keep the air pressure high in the cooling plenum this increases / maintains airflow through the oil cooler. Okay, that sounds good, so I “tighten it up a little” and added more weather stripping on the bottom. The results were measureable and it reduced the oil temps by about 4 degrees F, but I was looking for something better.
Before we get going with the mods here are the current numbers after additional weather stripping.
4,800 RPM, OAT 75F, Oil temps: 207F
5,000 RPM, OAT 75F, Oil temps: 212F
5,200 RPM, OAT 75F, Oil temps: 220F
5,400 RPM, OAT 75F, Oil temps: 230F
A theory I have is radiant heat from the muffler is diminishing the cooling capacity / efficiency of the oil cooler. The muffler is about 1 1/4” away from the oil cooler. As I understand it, and in talking with qualified engineers air flow does not reduce the effect radiant heat has on an object. I decided to add a fiberglass heat wrap barrier to the muffler.
The above picture shows the muffler proximity to the oil cooler.
Here are the results of the test after the heat barrier was installed.
4,800 RPM, OAT 75F, Oil temp: 195F
5,000 RPM, OAT 75F, Oil temp: 209F
5,200 RPM, OAT 75F, Oil temp: 215F
5,400 RPM, OAT 75F, Oil temp: 222F
5,400 RPM, OAT 85F, Oil temp: 230F
It appears I might be onto something here as the temps are definately lower with just a minimal amount of exhaust wrap. I will post the results of further Non-Van Aircraft Approved Tinkering. I would like to try a heat sheild, but getting to close to the oil cooler could only diminish the airflow. I can see some serious tinkering thinking is in the future!
Here is a link to the material used. http://www.aircraftspruce.com/catalog/eppages/graphblkwrap.php
Do not use a product like this http://www.jegs.com/i/Thermo Tec/893/16850/10002/-1?CT=999
as it will not take the 1100F as advertized. Ask me how I know.
Your mileage may very.
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