Hi Paul,
My 20B project has gotten delayed for the last 9 months while trying to
build a house, but I'm back at it now. I've decided to go normally
aspirated P-Port, but as I started looking for P-Port Housings, I became
concerned about which housing are correct for the 20B. Racing Beat has
several p-port housing available but of course none say they are for the
20B. The ones listed are:
1) Peripheral Port Housings 1986-92 Racing Beat 13B Non-turbo
2) Peripheral Port Housings 1986-92 Racing Beat 13B Turbo
3) Peripheral Port Housings 1974-1985 Racing Beat 13B Non-turbo
4) Peripheral Port Housings 1974-1985 Racing Beat 13B Turbo
Which one is the most appropriate for the 20B? Or, is it better to have
someone convert my original housings? I was planning on using the 89-91
NA high compression rotors (9.7:1). If machining my housings is best,
who can do a quality machining job of this for me?
Secondly, I'm trying to decide on 2mm -vs- 3mm Apex seals. What are
your thoughts on this for normally aspirated P-Port aircraft
application? If 3mm is best, again, who can do a quality machining job
of this for me?
Thanks again for all your knowledge and expertise!!
Don Mitchell
Number 2 is best but I am sure they are more money.
If you had your current housings done Jim Poole can bore
the holes but then you would need someone to weld them and finish
the the minor porting required. Mazdatrix are capable of the whole
job so you might check with them. Two mm stock apex seals are fine.
All stock seals are now two piece and based on RX8 technology.
I don't recommend after market apex seals except for Ianette ceramic.
No one has the capabilities to make them correctly and some
can wear out your rotor housings sooner rather than later.
Paul Lamar ...No rotor no motor.
Paul,
Why the Turbo housings? I thought the non- turbo with higher compression
ratio would be best. I guess it all depends of what power you were wanting
and if you intended using a turbo or not!
Don the 3mm will withstand a little detonation (so I'm told- no first hand
knowledge) but don't seal as well as the 2mm, but if you were wanting to use
a turbo and wanted a little more insurance against detonation use the 3mm.
If your wanting more compression use the RX8 rotors, but they have their own
set of problems with short side seals.
If you can afford the factory PP it would save a fair bit of work if you do
it yourself, and may be cheaper than having it done. What are they asking
for a factory PP and are they new?
George (down under)
-------------------------------------------------------------------
The rotor housings have nothing to due with the compression ratio
George. The rotor controls the compression ratio. You know that :)
The late turbo rotor housings have a cooling enhancement
modification.
The other problem with the 3 mm apex seals is they are not
made by Mazda. Not only do they not seal as well but they are
death on rotor housings because they are made from billet steel
and NOT cast acicular iron laser heated and nitrogen cooled
as the stock Mazda seals are. Cast iron seals are porous and retain
lubrication and therefore have lower friction. This has been known
almost from the dawn of the internal combustion engine. Perhaps
further back than that to the dawn of the steam engine. After
market apex seals have the potential to give the rotary a black eye.
http://www.rotaryeng.net/history.html
http://www.key-to-steel.com/default.aspx?ID=CheckArticle&NM=21
" 2. Acicular Irons.
Carbon 2,9-3,2, nickel 1,5-2,0, molybdenum 0,3-0,6%. Copper can
replace nickel up to 1-5%. This rigid, high-strength,
shock-resisting material is used for diesel crankshafts,
gears and machine columns. With the correct amounts of nickel
and molybdenum correlated with the cooling rate of a particular
casting the pearlitic change point can be suppressed and an
acicular intermediate constituent (ferrite needles in austenitic matrix)
can be produced with high mechanical properties. Acicular cast
iron is very much tougher than any of the pearlitic cast irons
of lower strength. The tensile strength of acicular cast iron
with a carbon content of about 3,0% will vary from 380 to 540 MPa
but these figures can be maintained in quite large sections.
Phosphorus should not exceed about 0,15% in the presence of molybdenum,
otherwise a compound is formed which impoverishes the matrix
of molybdenum. Quite large variations in silicon content can
be tolerated, but chromium in excess of 0,4% is harmful.
The structure changes rapidly at 600-750°C and these irons
should not be used at temperatures greater than 300°C.
[572 degree Fahrenheit]"
Since it is not a turbo engine you don't need to worry about
detonation.
Paul Lamar ...No rotor no motor.
The Rotary Engine NewsLetter. Powered by Linux.
ACRE NL web site.
http://www.rotaryeng.net
Copyright 1998-2007 All world wide rights reserved.