Subject: 20b vs 13b
From: rotaryeng
Date: 1/19/2013, 4:13 AM
To: AAAA-rotaryeng



Paul, In your opinion, which is the better install, 20b or a 13b?  I'm
building a 3500 gvw Murphy moose.  Eventually I'll put it on floats.  I'm
looking for about 300 to 350 hp.  I am brand new to rotaries but in the last
few weeks I have tried to absorb info from many different web sites.  Here
is what I think I know.  The 13b would need to be far more modified; ported,
turbocharged.  It would have more available parts for a rebuild.  The 20b,
stock is at 280 hp.  The apex seals are taller?  And may not be as good as
some aftermarket 13b seals?  20b has more torque given the same hp as a 13b.
I've also read about aftermarket 3 rotor renisis builds with non Mazda
e-shafts (homemade).  There are so many different variables, I was hoping to
get advice to gain knowledge to eliminate some choices.  Up to now I was
vacillating between an io-540 and a m-14.

Thanks, Paul lennemann.

The apex
seals are interchangeable.  For that application a 20B would be much better.
You can not have too much power for a heavily loaded float plane.  Ken
Welter effectively uses NOS to get his 3000 pound Coot on the step and out
of the water in less than 10 seconds with a 2 rotor.  I would use a 375 HP
P-port 20B and use NOS for a few seconds to get it on the step and out of
the water.  That should give you around 450 to 500 HP.  Won't hurt the
engine.  Ken has burned hundreds of pounds of NOS so far.

Don't waste your time with a side port engine.

 Paul Lamar

Thanks Paul.  It helps to know what to focus on learning.

Paul

 Read this for more background on P-ports.

http://www.rotaryeng.net/__intake.html <http://www.rotaryeng.net/intake.html>

 Paul Lamar



Paul,
When you p-port the 20B, do you need to fill in the inside portion of the
side housing or do you just plate it on the outside face?
Paul Lennemann

We use a sealing plate on the outside with an O-ring.
Jeff makes those up for us. You can get these directly from Jeff.
See the bottom of the first page on the web site.
When he bores the hole for the p-port ss tube he machines the rotor
housing flat in that area.

You can fill the inside area if you wish. I would use silicon rubber.
Easy to dig out if you have a problem

BTW we have over 74,000 hits on this you tube p-port video :)
http://www.youtube.com/watch?__v=NKJ00JsnS8A <http://www.youtube.com/watch?v=NKJ00JsnS8A>

Paul Lamar



Paul,

I think he's asking what to do about the old intake ports in the side housings.  I filled mine with Devcon.

Mark S.

Cheaper silicon rubber is good for that too. You can buy it in the hardware
store or Home Depot.

Paul Lamar


The Rotary Engine News Letter. Powered by Linux.
ACRE NL web site. http://www.rotaryeng.net
You Tube http://tinyurl.com/beqqxas
Copyright 1998-2013 All world wide rights reserved.