From: "Stephen Izett stephen.izett@gmail.com" <flyrotary@lancaironline.net>
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Subject: Re: [FlyRotary] Sump Breather?
Date: Sun, 1 Nov 2020 22:28:27 +0800
References: <list-891772@logan.com>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
In-Reply-To: <list-891772@logan.com>
Message-Id: <F546B066-A222-4482-A33B-E1B65A85E255@gmail.com>

Thanks Lynn and Jeff.

Appreciated. My vent is probably only 3/16 inch and It just had me =
thinking!

Cheers

Steve

> On 1 Nov 2020, at 9:01 pm, lehanover lehanover@aol.com =
<flyrotary@lancaironline.net> wrote:
>=20
> Crank case pressure is a function of the volume of combustion gasses =
escaping past the side seals and through the end gaps at the side seal =
ends and corner seal fitments.=20
> =20
> There will always be some flow even on a new engine. So the trick is =
to keep the outbound flow speed low so as to keep escaping oil droplets =
falling back into the engine rather than being expelled. In racing we =
are required to have a catch bottle with a minimum volume of 1 quart. A =
well done rotary has a remarkable low flow rate and can get along fine =
with a small diameter vent tube. Not a big problem on the street.=20
> In the aircraft the flow will be higher as the engine is usually run =
at or near full throttle for long periods.=20
> So run it hard and look into a catch bottle to see how much oil is =
being lost. A few drops to nothing is ideal.=20
> Most can be vented into the intake flow but that will not show up any =
problems. Every landing needs a oil level check. If the breathing is =
restricted, pressure may push out a seal or turn a seal lip over =
backwards. Followed by much oil loss. I shorten the seal springs and =
build seal retainers on each engine. You can also buy double
> lip seals with one lip facing in and out. Keeps dust out of the seal =
lips.=20
> =20
> This is seldom a problem and did not occur on showroom stock Mazda =
rotaries that were turned up to high RPM. So probably not a factor.
> Lynn E. Hanover   =20
> =20
> In a message dated 11/1/2020 4:57:53 AM Atlantic Standard Time, =
flyrotary@lancaironline.net writes:
> =20
> Hi Lynn EH and all
> =20
> What size breather from the sump is required?
> Is this the same for all the various models (particularly the =
Renesis)?
> We have the OEM sump but removed the plastic manifold and put a filler =
cap with small breather on the top of the steel vertical tube that runs =
down into the pan.
> What would happen if this breather was too small?
> =20
> Thanks
> =20
> Steve Izett
> Perth Western Australia.
> =20
> =20
> =20
> =20
> =20
> --
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