W

WatkinsT1

Member
In the current issue of RVAtor on page 14 an article refers to the "Recommended" baffels added to his Superior engine in front of #1 cylinder and a smaller one in front of #2 to correct a miss match in temps at cruise. I have a Superior engine and also have this miss match and have been looking for anyone that has done this. Can anyone point me to someone that has done this or posted any pictures of what they added that worked. Thanks

Tod
N359HW
 
Baffle plates + washer

Tod

On my superior engine I started by looking at the temps of all 4 cylinders in the cruise at 65% power as a base line and noted the differences.
I put a washer as recommended by others behind #3 to open up a little gap with the baffle which improves cooling. I then added small baffle plates in front of #1 + #2. I fixed these plates with -6 screws and nuts (platenuts would be even better) so I could remove to adjust.
After several flights I ended up with the plate in front of #2 about 2 inchs high and the plate in front of #1 about 1 inch. The total spread of CHT's was 4 degrees from hottest to coldest and two degrees between #2-4 and #1-3.
It took quite a few flights to achieve however now if anything changes it should show up as a cht difference and will help pin-point any faulty plugs etc.
The new baffle kits (post 2008 or so) include these baffles I believe, pre 2008 just mention it somewhere in the text saying add if required.

Hope that makes sense

Peter
 
Superior baffles

Peter,

I too have a superior in a 9A, and will tackle the baffle installation.
I have been trying to get a picture of this installation for some time. Could I trouble you for a couple of snapshots of your installation? I am sure this could benefit quite a few of us.

Thanks so much,
Chris
 
Here's a picture of my baffles on my Superior. This is the newer baffle kit on my 7 which included the front air damns. I also did a retro on an RV-8 using air damns up front to balance the CHTs. It does take some whittling and test flying to get them the correct size.

 
Rocky....

...I have a question for you. I have just started my phase 1 flights, and see that my temps on cylinder 1 is low as compared to 2 (a bit higher), 3, and 4. From your attached picture, it looks like the cylinder head fins on # 2 are completely blocked, and the ones on cylinder #1 are about half covered. Is the picture your final solution and are all cylinders within "range" of each other?

My -6A has the old style baffles installed, and I need to start thinking about balancing the temps. Thanks...
 
I installed the Van's supplied baffles

for my Superior 180hp and had major CHT problems with my front (#1 and #2) cyls. during my early phase 1 flights. Admittedly, I was testing at near 100F temps in Las Vegas, May of this year. After trying all sorts of things (including extra openings in the lower cowl for more exit area), I attacked the cylinder front baffles. I ended up cutting them both to under 1" and now have well balanced (and much lower) temps. The full size baffles supplied by Van's were dramatically reducing the airflow into the cowl especially at the #1 cyl. :(

My recommendation is to leave them off for your first flights, and add a piece of aluminum foil tape to the front of the cylinders, cutting it to get your CHT balance just right. Only then should you make the final pieces from aluminum.

I don't think you will have enough room for nutplates between the front baffle angles and the cylinders. Tapped holes might work and avoid you having to disassemble the front baffles to install the final aluminum Cyl. baffles. Haven't tried that yet. Good luck!
 
Chris

I'll try to get a photo next time I'm at the plane and post it.
Looking at Rockies photo the plate in front of my #1 clyinder is 1/2 that size. Also #1 seemed to be very sensitive to small changes where-as #2 was larger and not so sensitive. In the end I was taking as little as 1/8 off to get the final adjustments.

Peter

Just found a photo but only the #2 remember #1 plate is 1/2 this size!

 
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My cylinder blockers are are about 1-1 1/2".
I believe they are still a tad to large. Trimming would achive more balance.
In high performance cruise, they run a bit on the hot side compared to #2 & #4. By the hot side I mean about 360 with about 5-10 spread.
Low perf cruise I'm at about 2-3 spread.
I like to run it LOP and the spread comes back to about 5.
This seems to be my sweet spot running at 2500rpm, 8.7gph, 188-190mph.
BTW, I'm running with the forward induction so my intake is a bit different.
 
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I did cut down the #2 baffle slightly about 1/8" after I started flying. My CHTs are very even within 5 to 10 degrees. At cruise I see 340 to 350 normally sometimes a little lower depending on OAT. I also have nozzles spraying the pistons with oil which I believe helps maintain more constant CHTs. My RV-7 cowling has a center ramp making the inlet to middle transition on the baffles more air tight. I'm very happy with the setup.
 
superior baffles

Many thanks to all...I get the idea now. I wondered how wide the baffle had to be. Looks like it just encompasses the width of the cylinder head itself, as opposed to blocking the head and cylinder barrel from the airflow.
I assume the baffle lays tight against the head, or is there airspace behind the baffle??

Thanks a million,
Chris
 
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