Van's Air Force
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cylinder 2 bipass
- Thread starter gsimatos
- Start date
Mike S
Senior Curmudgeon
Welcome to VAF
Gary, welcome aboard the good ship VAF
There may be a thread in the builder tip forum detailing this-----have you checked?
If not, search for threads, and put in DanH as the thread starter, and reset the time to any.
Here is one-------- http://www.vansairforce.com/community/showthread.php?t=37835&highlight=bypass
Gary, welcome aboard the good ship VAF
There may be a thread in the builder tip forum detailing this-----have you checked?
If not, search for threads, and put in DanH as the thread starter, and reset the time to any.
Here is one-------- http://www.vansairforce.com/community/showthread.php?t=37835&highlight=bypass
Last edited:
Toobuilder
Well Known Member
O-320 E2D. #2 cht always running hot. Cylinder fins looked good. Verified it wasn't a bad probe. Worked with the baffles and cowl sealing forever, and considered everything as near to perfect as I knew how to make it. Then I tried several different modifications of the lower ramp, and the upper ramp. Nothing seemed to work, and I was considering the bypass some have had some success with. Then...... As a last resort before going into butcher mode, I thought I would try moving the lower inlet ramp forward about a quarter inch from where it normally rests against the front of the cylinder. Success!
That is correct. I moved the lower inlet ramp forward creating a 1/4 inch gap between the #2 cylinder and the ramp. It' simple, and it worked for me after everything else I tried didn't. Kinda like the washer trick some people use for heat issues with #3 and #4, only it's a gap out front.
OK Thanks seems like regardless of the approach, you have to get air
UNDER the cylinder to cool that 1/4 of its circumference
Im clear now on the strategy. Im going to do it this week and will get the results to you all. Love the plane want to be able to use it confident my engine is happy
cheers G
UNDER the cylinder to cool that 1/4 of its circumference
Im clear now on the strategy. Im going to do it this week and will get the results to you all. Love the plane want to be able to use it confident my engine is happy
cheers G
Toobuilder
Well Known Member
Yes, getting air to the lower fins is the goal... But so is deltaP. "Spacing" the baffles or the "washer trick" often opens a large gap (leak) at the outboard section of the cylinder where you want it to remain sealed. Yes, you get air to the lower fins, but you also dump a bunch of deltaP in the process. This is why a dedicated bypass (which emulates the duct formed by a paired cylinder) is the best approach.
Marc Bourget
Well Known Member
Michael,
I think he meant moving the ramp a short distance away from the cylinder (at about the midline of the cylinder?) but I believe he kept the baffle tight towards the "6 O'Clock" position or bottom of the cylinder.
There is precedence regarding this approach in the NACA Reports.
FWIW
I think he meant moving the ramp a short distance away from the cylinder (at about the midline of the cylinder?) but I believe he kept the baffle tight towards the "6 O'Clock" position or bottom of the cylinder.
There is precedence regarding this approach in the NACA Reports.
FWIW
Toobuilder
Well Known Member
Yes, I'm familiar with the "eccentric" baffle treatment detailed in the early NACA reports, and it makes sense to me. However, I'm talking about the leak path created by spacing the baffle away from the cylinder at the "top" half of the head. The space between the rocker cover surface and the upper portion of the "zero fin depth" area of the head should be sealed air tight. No air should pass from top to bottom here because there is no cooling taking place if it does.
I apologize for my lack of clarity, and I don't have pictures, but yes, the baffling is still tight against the cylinders 6 o'clock. I changed nothing else with the baffles other than moving the trailing edge of the lower inlet ramp forward to create the 1/4 inch gap between it and the cylinder. I have no idea how this has changed inter baffle pressures and airflows. I do know it has worked for me, that my hot cylinder is now in line with the other 3 cylinders. I don't have the instrumentation, nor the patience, to work it out technically and present it here. I was simply trying to pass on what happened to be a quick and simple fix for my issue. It might possibly save somebody else all the wasted time and effort I used up to find a fix.
