ENGINE COOLING

[Hornet2008]

So looking at link in post #6 page 2 to create a plenum to channel air past the area with little or no cooling fins on #2 cylinder. My question is do you drill a hole in the inlet ramp for air flow into this plenum? There is little or no gap behind the Al angle and vertical plate on this cylinder.
I have done the mod to #3 cylinder and was markedly cooler during a ground run. I have yet to fly with it. Have to thank all the people that take the time to help, it is very much appreciated.

[F1R]

Originally Posted by Hornet2008

So looking at link in post #6 page 2 to create a plenum to channel air past the area with little or no cooling fins on #2 cylinder. My question is do you drill a hole in the inlet ramp for air flow into this plenum? There is little or no gap behind the Al angle and vertical plate on this cylinder.
I have done the mod to #3 cylinder and was markedly cooler during a ground run. I have yet to fly with it. Have to thank all the people that take the time to help, it is very much appreciated.

In short, yes.
To see the drilled holes, see post number 10 on page 1 of the link.
Michael Robinson (toobuilder) shows an angle valve cylinder #2 with the drilled holes visible in the first photo before the plenum is in place.

I suspect the plenum in post #12, is deeper front to back and would allow holes to be drilled( or an oval /rectangular port) in the ramp ahead of the angle bracket.

[Toobuilder]

The simpler duct shown in post #16 of my other thread is now my default bypass duct. I have one on cylinder #5 on the Rocket's new baffles as well as an identical example on #2. The one on #2 includes the full wrap around the top fins, so it has the appearance of the fins being completely "blocked" to the incoming rush of air. This is an experiment for me and my hope is the total plenum volume is large enough that the local airflow velocity will be low enough to "turn the corner" and flow down through the fins as in the rear. This may not work on a standard Vans cowl, and it may not work on mine. That said, it will be easy to trim off the top half of this duct flush with the inlet ramp floor and allow air entry through the funnel of the bypass duct. If you dont have the physical space because the air filter is there, then a short but wide duct is the answer. A series of half inch holes serving as the inlet is not ideal but keeps some of the structural integrity of the angle intact.

[NYTOM]

Originally Posted by F1R

Click on the link on post #6 , then go to page #2, and see post #12 by alpinelakespilot2000. That shows you most of what you are asking about.

it is only Cyl #2 on the front side that has the shallow fin issue.

Yes, now I see. Would you do that on Cylinder 1 also? And how about #4. I have never seen any thoughts on widening the gap at the left rear of the baffling near the oil cooler. Excuse my moronic questions. Trying to fulling understand and eliminate any cooling problems that might occur. And could there be any downside to fabricating and adding these extra cooling ducts.

[BillL]

Here you can see the slot and flange removed for the inlet side of #2 cylinder.

[F1R]

Originally Posted by NYTOM

Yes, now I see. Would you do that on Cylinder 1 also? And how about #4. I have never seen any thoughts on widening the gap at the left rear of the baffling near the oil cooler. Excuse my moronic questions. Trying to fulling understand and eliminate any cooling problems that might occur. And could there be any downside to fabricating and adding these extra cooling ducts.

1 & 4 do not have that issue. If you look at those cylinders the fins are deeper where they come up against the baffles in the #1 #4 position and there is plenty of airflow.

It will become very clear if you just look at some cylinders. All 4 cylinders are the same, but the shallow fin section of 1 and 4 merge with a deep fin section of 2 and 3, so they have plenty of airflow as a result.
Therefore 1 and 4 do not need the bypass in the baffle face.

It is only #2 and #3 that have the shallow to virtually no depth of fins where they run up against the baffle wrap. That is what the Dan, Michael and Bill are trying to illustrate and the OP was trying to make people aware of. There are a lot of RV's and other home builts with Lycomings that people have not seen the solution for, nor do they understood there is a cooling issue that can be easily cured.



Wow, but that is nice work Bill.

[NYTOM]

Originally Posted by BillL

Here you can see the slot and flange removed for the inlet side of #2 cylinder.

Ok, now I got it. Sure doesn?t take much does it. I?m going to use these photos as guides. Thanks in advance for hopefully a cool running motor.
Hope mine look half as nice as yours.

[rightrudder]

Great thread, and timely for me as I'm going to do some baffle modifications at the next oil change to lower CHTs

I think this would make an excellent sticky....great photos and links to threads that Dan H. has compiled.

[walter]

I used the RV-14 Baffles on my RV-8A powered by an XP400 and the fit is very good.
Bottom right of this photo shows the updated #3 aft baffle (upside down). Note the deep channel and the standoff.

[Robb]

My cylinder head temps are fine no matter how hot it is in my 7. The issue I have is with the Sam James plenum and minimum space for the oil cooler inlet duct. I increased the opening , added a larger oil cooler and a 4 inch Scat tube. I have to watch it as it will get to 230 degrees if not at cruise altitude. It settles down to around 215 in cruise. Still working on a fix but its better now than when I purchased it. I am 195 HP with 10 to 1 and oil squirters. Also e mag p mag ignition. I guess this is what you have to deal with on experimental airplanes. My Husky stays cool no matter what temp it is so this is new to me