Is anyone familiar with how to remove the plastic oil fill inlet on the
Renesis.  I hate to take a chance on breaking the plastic, so if anyone
knows how it removes??
I also wonder the same thing about the 2nd gen 13B.  It has a metal
inlet, and would probably be removed in a similar manner.
Tracy, you cut yours off on the Renesis and have expressed
dissatisfaction with the result.  Oil blowby, I think.  how did you do
yours??  I am thinking about trying to modify the 2nd gen inlet for the
Renesis.  Has anyone done this?  What excellent ideas are out there for
lowering this inlet?
Bill Bradburry

Blowby is a natural outcome of leakage of combustion gas past the corner, side seals, and oil scrapers. The older the engine, the bigger the gaps between the side seals and side seals, and that means more blowby.

 

So, when I build an engine, I use zero clearance between the corner and side seals. So long as I can depress the corner and side seals together and have them pop back up by themselves, it will be a screamer, and have zilch blowby.

 

The problem with blowby is that the stock breather is about 1/4" ID and therefore the flow velocity is high enough to carry away any liquid oil in the filler neck. Even race engine builders seldom use more than a dash 10 hose for the breather.

 

I use a dash 8 hose assembly but I have no breather issues with the dry sump pump. The breather hose actually sucks oil and vapor from the storage tank into the sump area, because the scavenge section displaces far more than the blowby.

 

If you must shorten the filler neck then I would leave the cap off and use a formed 90 hose over the end of the neck. The bigger the diameter the lower the velocity of the blowby, and the smaller the amount of oil it can pull out. This is a big improvement for piston engines also. If you run a crank trigger, you can use the distributor hole as another breather location. You might want to mount a baffle plate on the inside so the gear cannot sling oil directly up the hole. If nothing seems to stop it, you can use a real airplane oil separator and run the recovered oil back into the sump.

 

The taller the filler neck and the closer to the top the breather fitting is mounted the better.

 

Even in the cap would be good. 

 

The filler necks are pressed in, and can come out without notice. You can weld or braze on a couple of tabs and wire it down. I have never worked with the plastic parts, so I cannot help there.

 

 

Lynn E. Hanover