What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

New RV-12 exhaust. Value of new "old" style"?

Rick_A

Well Known Member
Van's came out with a re-designed exhaust system for the RV-12. The main feature is that the muffler is moved rearward to provide more space between the oil cooler and the muffler.

The new exhaust system is $1,285. I have a new "installed" but never used original system (Van's is not doing a trade-in). Any thoughts on the value of my exhaust system if I buy the re-designed one from Van's?
 
How much has been redesigned in the new system? From the revised plans, it looks like just the four exhaust pipes between the muffler and the cylinders. The muffler itself seems unchanged, but you'd have to check with Vans to be sure. Might be a relatively cheap upgrade if it's only the four pipes.
 
Any thoughts on the value of my exhaust system if I buy the re-designed one from Van's?

Price it right (say 50% of the pipes cost) and you might be able to sell. Some have noticed quite a bit of corrosion (thru wall) near the pipe socket to muffler connection.
 
Last edited:
Looking at the new exhaust plans (they are on Van's website), it looks to me like the pipes have been re-designed to move the muffler aft.

It also looks like the tail pipe now goes straight down through the hole in the bottom cowl - not angled back like the original design. So the new system includes a new muffler - not just new pipes.

Per the new instructions, the tail pipe is already the correct length. It does not need to be shortened.

Marty, thanks for the input. If I could get 1/2 the cost of the new system for the one I have, I would probably do it.
 
It also looks like the tail pipe now goes straight down through the hole in the bottom cowl - not angled back like the original design. So the new system includes a new muffler - not just new pipes.

Correct.
The muffler is the same as what you have but with the tail pipe welded on in a different position.

It may be possible to purchase just the 4 pipes and then you could cut the tail pipe off of yours and have it rewelded. If you plan to certify E-LSA this may complicate that though.
 
Scott,

Was the design change an attempt to lower oil temperature in hot weather?

Yes.

The new system moved the muffler aft somewhere in the range of 4-5 inches (I don't remember the exact amount.
Surprisingly, it was not as beneficial as most people might think.
If I remember right, it produced a reduction of about 7 degrees.
But, some reduction is better than nothing, so the design change was implemented.
 
Yes.

The new system moved the muffler aft somewhere in the range of 4-5 inches (I don't remember the exact amount.
Surprisingly, it was not as beneficial as most people might think.
If I remember right, it produced a reduction of about 7 degrees.
But, some reduction is better than nothing, so the design change was implemented.

Interesting. I got a 5f (if I remember right) oil temp reduction when I installed a heat shield around the muffler to shield heat from the oil cooler.

RV-12_muffler_shield.jpg
 
Yes.

The new system moved the muffler aft somewhere in the range of 4-5 inches (I don't remember the exact amount.
Surprisingly, it was not as beneficial as most people might think.
If I remember right, it produced a reduction of about 7 degrees.
But, some reduction is better than nothing, so the design change was implemented.

Just curious which 12 you used as a testbed? Any chance it was New Blue?
 
Moving the oil cooler forward, I saw a 10-15 degF decrease during a WOT climb. IMHO, moving the oil cooler forward, improves the airflow to the oil cooler. The modification is quite simple and am surprised Van's did not chose this solution as originally proposed by Dave Farmer.
 
When making design decisions data is important. So the first question that would need to be ask regarding relocating fwd is, "did it reduce the temps 10 degrees or 15"? There is a big difference between the two.

Moving the cooler fwd vs the muffler aft should not produce much of a difference in oil cooler performance. Moving the cooler fwd likely raises it vertically behind the opening but that shouldn't make much difference. The cooler is not relying on high speed ramp air, but mostly static pressure within the cooling duct.
Without knowing the process for making the mold plug and the molds for the duct, you wouldn't know that moving the muffler was much easier.

It also allowed for doing a before and after flight test only one hour apart (quick change of the exhaust system, then retest) which allowed getting very accurate test data.
 
Can i get a look at the new muffler ?

Where do I find the new muffler, image or dimensions ?. I am seeing high temps and would like to consider modifying mine.

Tom O.
 
Moving the muffler aft requires changes to the entire system, not just the muffler.
I just suggested that people could possibly purchase the 4 new pipes and reuse their original muffler by re-welding the alignment of the exhaust pipe.
 
I'm operating out of Phoenix. If I can survive 3 summers of operation out here with minimal pauses in climb to let temps settle I would think the oil temp issue with the original design is acceptable if not optimal.
 
I'm operating out of Phoenix. If I can survive 3 summers of operation out here with minimal pauses in climb to let temps settle I would think the oil temp issue with the original design is acceptable if not optimal.

A fair statement assuming that all situations (clearances) are the same, but this is simply not the case. It has been widely proven. I am flying my 2nd 12 and just as soon as I was able to observe the clearance between the oil cooler and the muffler, the cowl duct surgery was performed. I don't even give hot weather a 2nd thought, nor do I step climb. I am glad this has been addressed, it is unfortunate for those that have recently bought their engines that it will cost a lot of loot to correct it. The cowl mod takes a day or so and can usually be performed for $20 or less.;)
 
Correct.
The muffler is the same as what you have but with the tail pipe welded on in a different position.

It may be possible to purchase just the 4 pipes and then you could cut the tail pipe off of yours and have it rewelded. If you plan to certify E-LSA this may complicate that though.

Scott,

As long as new header pipes are Van's, and muffler (new existing) w/pipe re welded per plan....how would this complicate e-lsa?
 
Back
Top