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I'm at the point of my build where I am installing the fence baffles to the engine. I purchased the laser cut baffle kit from Sonex.

The instructions for the installation of the baffle kit are, at best, vague. Included in my kit is a single 2x4ft blueprint detailing bends to be made in the various laser cut parts, plus a collection of photos of installed baffles. Beyond this, it appears to be up to the builder to just "figure out" what happens next. It seems to me that a knowledge of how baffles work is assumed to be known by the builder, but this is a leap in logic compared the most of the rest of the build (with the exception perhaps of instrument panel/electrical system choices.) I did build my Aerovee engine and the manual did well to guide me through a process with which I was altogether unfamiliar.

I'm hoping to collect some information/knowledge here about fence baffle installation, both to help with my own build and to help others who reach this step.

Some particular concerns I've experienced at this point:

-There is no picture anywhere in the kit that shows where the bottom baffle goes or how it is attached. This might become obvious during the latter stages of installation, but after reviewing the parts and plans I have no clue.
-There are definitely differences between the laser-cut parts and the blueprint page. One example is the shape of the rear baffle that is screwed to the engine case.
-It's not made clear that certain screws in the cylinder heads are actually to be used to mount the baffles.... I was afraid to remove these screws thinking they were related to the valve system of the heads. Again, there is no clarification as to what is an appropriate mounting point for these baffles (although there are pictures of what the mounting brackets might look like.)
-Should the baffles be assembled in such a manner as to be removable during an engine rebuild, or are they disposable? My guess is the former, but again no guidance.
-There is no guidance for the top-mount oil cooler in the turbo-aerovee installation and its relation to the baffles. I suppose this will be custom, and will again rely on my understanding of the ultimate goal of the baffle system (which I do not yet possess.)

We all approach a build with different levels of understanding of aircraft construction, and the Sonex kit does a wonderful job of simplifying the build process for a lay person. Pardon (or don't) the pun, but presently the fence baffle installation has me.... baffled....

Hi Ryan,
I used the AeroVee fence baffle kit on my 2.4L VW engine. it required some modification as my engine is wider and the cylinders are shaped differently.
Anyway, here are some pictures of my installation which might answer some of your questions:

Ryan

I just went through this a few weeks ago. All I can say is it was a mystery to me too.

I ended up not installing the bottom piece after consulting with the factory.

The rest simply did not fit correctly so I did what I could to make it fit. The exhaust, for example, was way off the pre cut holes. I am guessing this is because I have a turbo kit with a different style exhaust, but could be builder error. (That would be me)

In the end it was a slow and frustrating process but I got it installed. I did end up using nut plates and screws to make it easy to remove, and so far that has paid off.


Robbie Culver
Sonex 1517
Chicagoland
Tails and Wings complete - finishing fuselage.
N1517S reserved

Sonex1517 wrote:Ryan

I just went through this a few weeks ago. All I can say is it was a mystery to me too.

I ended up not installing the bottom piece after consulting with the factory.

The rest simply did not fit correctly so I did what I could to make it fit. The exhaust, for example, was way off the pre cut holes. I am guessing this is because I have a turbo kit with a different style exhaust, but could be builder error. (That would be me)

In the end it was a slow and frustrating process but I got it installed. I did end up using nut plates and screws to make it easy to remove, and so far that has paid off.


Robbie Culver
Sonex 1517
Chicagoland
Tails and Wings complete - finishing fuselage.
N1517S reserved

Thanks Robbie. I'm someone who can't really progress on a new part of a build before I can visually interpret it in my own head. My thinking tells me that the bottom baffle is to provide airflow over the bottom of the case/bottom mount oil cooler, via the the airflow provided through the 3rd hole in the cowling (under the prop hub.). Since I don't have that 3rd hole (per Sonex advisement) and don't have a bottom oil cooler, I can imagine that the bottom baffle is totally unnecessary for me. The lack of direction in the instructions compound the issue.

I suppose what I'm really looking for, other than better guidance on how my purchased baffle kit should be installed, is a detailed/technical explanation of the ultimate goal. I get that airflow needs to be guided over the cylinder and cylinder heads, but how is the baffle system attached to the engine? How easily should it be removed? How do I include the top mount oil cooler in the turbo aerovee? etc

Ryan,

Sonex recently (last month) put out an instruction that shows how to do the baffles with the top mounted oil cooler. It is either under the service advisories or the newest version of the Aerovee manual.

Also, with the top mounted oil cooler you do not need the bottom baffle. Search this site for Joe Norris's posts on oil coolers where he explains that they have tried it with cooling air on the bottom and without it on engines with top mounted oil coolers and they have determined it makes no difference.

I recently went from a bottom mounted oil cooler to the top mounted oil cooler so this is all the same stuff I had to sort through.

Good Luck!

Jake

Jake, thanks, I'm unable to locate the Sonex instructions on baffles for the aerovee top-mount oil cooler (though I do see instructions for a Jaibru oil cooler), could you post a link to what you're referring to?

Regarding Joe's posts, I think what you're referring to is here: viewtopic.php?f=7&t=746&p=5551&hilit=+oil#p5551

Joe's comments seem to be mostly observational in that post, I don't read them as instructions regarding the bottom baffle. That said, I'm glad if we're able to compile this information in one place.

As part of my upgrade to the turbo I switched from bottom mount to top mount oil cooler. I did this several weeks before the turbo so I flew it before the upgrade with the top mount cooler. At that time I had the lower baffle in place and had good cooling. When the turbo went on, the turbo oil line interfered with the bottom baffle so I left it off. The cowl inlet is still open and I think helps cool the sump area and the new filter housing. I'm seeing 175 to 185 oil temp in this heat of arround 85 to 95 degrees. When it was cooler I was not quite getting to 150. with the top mount cooler I don't think the bottom baffle is needed. The only way to tell if the bottom opening is needed is to test the plane and see if the oil is too hot. My guess is not. One of my next experiments may be to cover the opening and see how the temps run.

rizzz wrote:Hi Ryan,
I used the AeroVee fence baffle kit on my 2.4L VW engine. it required some modification as my engine is wider and the cylinders are shaped differently.
Anyway, here are some pictures of my installation which might answer some of your questions:

Thanks for the pic's Michael.They will go a long way in helping when I tackle mine.
Mike

Ryan,

The Sonex instructions for the top mounted oil cooler baffle is located in this document on page 20:

http://www.aeroconversions.com/support/instruction_sheets/AeroVee_2point1_Turbo_Upgrade_Manual.pdf

Tony Bingalis in his EAA book entitled "Firewall Forward" describes in great detail the theory of air cooling of an aircraft engine.

In the case of the AeroVee, the intent is not just to put airflow through the cylinders, but to put pressurized air around the cylinders. The pressurized air aids in the cooling. The intent is for there to be high pressure above the cylinders and a low pressure zone underneath the engine to draw the pressurized air from above the cylinders. The heated air from cooling the cylinders then escapes downward and rearward out the cowling exhaust cutout.

The rear fence baffle will seldom be removed. It is attached to the engine block with sheet metal screws. Various lines and intakes pass through the rear fence baffle. The only time it is usually removed is for an engine rebuild.

The side baffles will come off often. Sheet metal screws attach it to the rear fence baffle and to the front baffle. One bracket is fabricated for each side that is attached to the heads with a machine screw.

The hardest thing for me with the baffles was getting them to line up perfectly with the cowling to form at tight seal. I initially used the weatherstripping supplied by Sonex in the baffle kit but later changed to a more conventional aircraft baffle seal silicon material from Aircraft Spruce.

Baffles are a hard thing to figure out and are hard to get properly trimmed to fit the cowling. I spent way too much time on my baffles.

Good luck!

Jake

Jake, great info and thanks for that link! The instructions for the baffle around the top-mount oil cooler is not included in the full 2.1 Turbo manual (versus the retrofit manual.) Also, the instructions you linked suggest that the baffle kits now include instructions and parts for the top-mount oil cooler. I had ordered my baffles with my turbo engine, and the baffle kit I received does not include anything (parts/instructions) for the top oil cooler. Part of the risk of being an early adopter I suppose!