to seal or not to seal?

[riobison]

On the O320 in my 9A, In changing the cyls I have noticed that there is a about 1/4" gap on between the inter cyl baffles and the case.

When I think about it, my old RV 4 was the same with the O360

In both cases they had never been sealed.

I have sealed everything else up really well and now I'm wondering how much of a difference if any, that has been seen by sealing this up?

Thanks

Tim

 

[Avanza]

Air that is passing through the cooling inlet will slow the speed of the aircraft.
Therefore it is important to seal of all leaks as much as possible.
Pressure differential between the baffling should be about 7" H2O in the O-360
engine. I think the O-320 is close to that.
Any air leak will reduce the pressure differential and engine cooling,
A thin line of sealant between the cylinder heads will improve the flow over the
fins. Minimize wasted air as much as possible.

Good luck

 

[BillL]

On the O320 in my 9A, In changing the cyls I have noticed that there is a about 1/4" gap on between the inter cyl baffles and the case.

When I think about it, my old RV 4 was the same with the O360

In both cases they had never been sealed.

I have sealed everything else up really well and now I'm wondering how much of a difference if any, that has been seen by sealing this up?

Thanks

Tim

I can not say how much, but my YIO-360 M1B (Vans) had lots of gaps, and I sealed them all. It's a pain to reach up there, but an extension for an RTV tube made it doable. IMO it is worth the trouble. Up to a point more flow past the fins is better, but I did find a limit for the parallel valve.

If one looks at heat flow as a series of resistances, the BTU to the airstream from the fins is one. My testing appears to show that up to a point more flow is better but over 14" h2o did not seem to reduce the CHTs any more, unlike an angle valve engine.

 

[Taltruda]

Are your internet cylinder baffles touching the cylinder base nuts, causing your 1/4 inch gaps? I’ve seen that and I have repositioned them to fit inside or above them and closed up the gap.. perhaps that’s the issue, or they are the wrong ones, but they should seal up.

 

[riobison]

They appear to be in there correctly all the way around. This is the way they are built. Gap might be closer to 3/16. With the previous engine there didn't appear to be any cooling issues. Every thing else is sealed tight and I hate to make too many changes before I know what this does with the new engine.