Muffler to Oil Cooler Spacing

I have searched the forum on this topic. The two threads that I found related mostly to the problems of high oil temperatures for some planes while flying.

I installed the oil cooler to my lower cowl and have installed the cowl to the plane. The oil cooler is hard against the muffler. I had help from an aircraft mechanic to do this.He suggested I may be able to rotate the muffler rearwards by adjusting the exhaust pipes slightly. I spent the afternoon trying to do this but I feel they seat in only the straight in position. There appears to be room for the muffler to be moved rearwards by adjusting the length of the exhaust pipes. The other option is to modify the cowl. The mechanic ask me to check the distance specified in the plans. The two threads have had posts about the gap but there does not appear to be a distance specified on the plan or in the threads.

I installed the cooling duct to the lower cowl as supplied. The cooling duct is supplied moulded to shape and although it has to be trimmed that trimming does not affect this distance.

I am looking for some comments on ways to sort this out. I can also email Vans for the spacing measurement.

Cheers

Julian 120316

Julian, I can almost assure you that if your cooler is within 1/2" of your muffler, your oil temp will be hot. In summer weather, it will be real hot. If you are interested, send me your email via pm and I will send you some plans and diagrams of the surgical procedure that will correct your impending problem. I can slide my hand between the cooler and the muffler.

Oil Cooler Mod!

Julian see my update on the Cowl Duct Modification thread i just posted. I think if you read the thread from beginning to end you will see how to modify your cowl to get the distance required to get proper cooling. If you ask Vans what the exact distance is let us all know what they say. At 3/4 inch distance on my 12 I don't have any problems except in the Summer here in Texas. When flying in a sea of air with a temp of 90f or higher that's when I start to see oil temps in the yellow arc. Below that I don't seem to have much of a problem. Good luck!

Mine is about 3/4" also. I don't have any oil T problems in cool weather (I live in PHX, so that means Nov-Apr). However, in summer I have to pause every 2000 ft or so when it hits 240F so it can cool down to about 228 in cruise at 4800 RPM. Then I climb 2000 and repeat the cool down.

Thanks for the advice.It looks like modifying the cowl and moving the oil cooler forward is the way to go. I have to wonder why I didn't check this spacing before getting the cowl painted.I also managed to ignore and miss all the help that has been posted.

From the posts above it looks like a one inch spacing may be the way to go.

Cheers

Julian

One other option - Ceramic coated muffler

I would like to see someone try and ceramic coat their muffler.
My exhaust on my -10 in ceramic coated and I feel like it makes a huge difference on the oil temp. When I fly with other -10's my oil is typically 20 degrees cooler.
The data on ceramic coating shows a significant drop a few inches away from a hot exhaust.

EXHAUST INSULATING WRAP

Has anyone tried this product from Aircraft Spruce? Simply wrap the muffler and solve the problem.

EXHAUST INSULATING WRAP
The original Exhaust Insulating Wrap was developed over 14 years ago by Thermo-Tec. Exhaust Insulating Wrap is an innovative way to create more horsepower and reduce under-hood temperatures. Wrapping headers maintains hotter exhaust gasses that exit the system faster through decreased density. Increased exhaust scavenging is produced along with lower intake temperatures. Exhaust insulating Wrap withstands continuous heat up to 2000?F, and contains no asbestos. Thermo-Tec exhaust wrap will not over-insulate a system when properly installed due to a proprietary coating developed by Thermo-Tec. --Thermal Conduction Technology (TCT) -- that conducts heat across the wrap's surface. This coating controls heat buildup and dissipation.

Some comments?

Any thoughts re the idea of Ceramic Coating the muffler or using the Exhaust Wrap as requested above??

Oil cooling problems!

IMHO after a lot of reports on this form and actions taken by others it looks like most of the high oil temps that occur on the RV12 during the summer are a result of the oil cooler being to close to the exhaust muffler. The muffler can exceed Temps in access of 1000F in flight. So when flying in a sea of air that is 90f or hotter and your oil cooler is less than 3/4inch from your muffler then no matter what you do like header wrap or ceramic coating you are still going to see hot oil temps especially in the climb. I have tried the header wrap and it didn't work for me. A friend has the ceramic coating which may have worked a little bit but he sees high temps to when flying in very hot out side temps. The cost for the ceramic coating can be expensive. Better to spend some time during the build to modify your cowling to achieve at least 11/2 inch clearance from the muffler then you will have no problems. See this tread from beginning to end to see how to modify your cowl if you have already finished your 12. Good luck!

http://www.vansairforce.com/community/showthread.php?t=89532

RV12Roger said:

Has anyone tried this product from Aircraft Spruce? Simply wrap the muffler and solve the problem.

EXHAUST INSULATING WRAP
The original Exhaust Insulating Wrap was developed over 14 years ago by Thermo-Tec. Exhaust Insulating Wrap is an innovative way to create more horsepower and reduce under-hood temperatures. Wrapping headers maintains hotter exhaust gasses that exit the system faster through decreased density. Increased exhaust scavenging is produced along with lower intake temperatures. Exhaust insulating Wrap withstands continuous heat up to 2000?F, and contains no asbestos. Thermo-Tec exhaust wrap will not over-insulate a system when properly installed due to a proprietary coating developed by Thermo-Tec. --Thermal Conduction Technology (TCT) -- that conducts heat across the wrap's surface. This coating controls heat buildup and dissipation.

Click to expand...

Roger, your post prompted some additional thoughts on the subject, and I am at a good point in the building process to address the heat issue, before it becomes a problem. I called Thermo-Tec, and spoke with Jim in Tech support. I gave him a pretty detailed desription of our engine installation, the exhaust system, the close proximity of the oil cooler to the muffler, and the heat issue that many RV-12 builders are experiencing. His recommendation was to use their wrap material to wrap all of the exhaust pipes, as well as the muffler. He feels that this will greatly reduce the overall cowling heat build up, and the oil temperature, due to exhaust system radiation. I will be starting the engine installation soon, and am considering following his suggestion to wrap all four exhaust pipes, as well as the muffler. What can it hurt??

Tom