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I am often amused by what goes for knowledge on the other
list. You have to keep in mind it was proclaimed about 10 years ago that
"Plugs Up" could not work in no uncertain terms.
Yes, I have often hear that myth - it goes something like
this. If you lower the fluid level in a pot of water then it won't cover
those items hanging from the lid - quite true. However, what the "experts"
apparently fail to do is to consider the fact that there is a fire hose
pump putting out somewhere in the vicinity of 20-30 gpm of flow. It is NOT
quite pot of unmoving water. The pump forces whatever fluid is in the
engine to gush through every available channel. I hooked up a ohm
meter to the rear coolant sensor (in plugs up it is also at the top of the
block) and verified that even without the full amount of coolant there is
coolant gushing though that area.
Its my opinion ( as contrast to unsupported assertions)
that by the time the coolant level has decreased to the level where it becomes a
problem to the plugs area, you have already cooked your engine. So need I
say - don't fly with a poorly designed or constructed cooling
system. Yes, I use stainless steel braided hose - for 10 years
now - never changed them and never had a leak. But, I do consider them
expensive and overkill. Get some top notch radiator house and change them
out ever 2 - 3 years.
Now, having said that, I did originally grooved the
coolant galleys of the rotor housings to trubulate the coolant flow more in that
area. Later Mazda started casting those turbulators into the housings - so
I have not done it for the last sets of housings. I found it
interesting that Mazda did that as they clearly weren't doing it for Plug Up
installations {:>). So I suspect that it was done because any turbulent
flow is better at carrying heat away than is a smooth laminar flow and not
because they hear Ed Anderson was using them Plugs Up {:>)
One person who shall remain unnamed cited seven different
reasons (why yes, I did keep count {:>)) why Plugs Up could not
work. I checked each one out - I mean the guy is right sometimes.
The last one offered was that the oil pump chain would not get splash
lubrication due to the orientation - SPLASH LUBRICATION!! - the last time I saw
that was used, was on an ancient tractor engine. It actually
had prongs protruding down from the connecting rods to splash oil up on the
journals of the engine. But, to have it suggested that the Mazda engineers
would use splash lubrication just amazed me.
That seventh myth was put to rest by somebody on the list
who while using a drill to spin the oil pump discovered that the Mazda engineers
had put a pin hole size hole in the aluminum pump housing which
sprayed a continuos stream of oil on every link of the chain that went
past. Nuff said about that.
There is NO technical reason not to go Plugs Up
with the older 13Bs, I can't say about the Renesis as I understand there was
some changes to the casting to accommodate the side exhaust and I have not
looked into it.
Now, here are some facts. 1. The Plugs are on
the top (you knew that didn't you {:>)) where they are much less susceptible
to being downed in gasoline - flooding is not a significant event for the Plugs
up installation (also makes it a tad bit easier to change in my opinion)
2. The exhaust points straight down which simplifies the exhaust
considerably - just down and back - also drains the combustion chamber.
3. Since the intake manifold and injectors no longer sit above the hot
exhaust stack (but on the same plane) there is much less likelihood of a
fuel leak causing a fire by having fuel drip on the hot manifold.
4. There is much more room to experiment with
intakes as the tubes do not have to run across the top of the engine.
5. The high profile items like the water pump and alternator are now below
the cowl line without moving or modifying them, etc, etc.
But, I will continue to point out that the vendors are not
making products for the Plugs Up orientation and therefore there are a number of
things you will have to do or have done. 1. You motor mount is going
to be a custom job, 2. You will need to build an oil sump as the pan
location is now on the side of the engine. That's about it as far as comes
to mind at this point.
Hope it helps in your decision.
Ed
----- Original Message -----
Sent: Monday, June 25, 2007 6:06 PM
Subject: [FlyRotary] Re: plugs up. Was
Method of killing power??
Ed,
The other list said that
there was a possibility of boiling the coolant in the cavities near the plugs
with the plugs up install. Did you do the modification of removing some
webbing to prevent that, or, do you find boiling no problem?
Ben (seriously
considering plugs up)
Acroduster Too
20B {under
construction}
----- Original Message -----
Sent: 06/25/2007 5:48 PM
Subject: [FlyRotary] Re: Method of
killing power??
Ed, It is interesting to note that the Curtis-Wright rotary
engine had
the long axis of the throchoid at about 45° with the plugs on
the high
side! Semi plugs up. The exhaust port was near the bottom. So
your way
of thinking has support. I've never thought plugs up was bad,
just
certain people do. You do have to have a better fabrication ability
than conventional installs. the lack of available equipment is the
biggest drawback.
Bill Jepson
-----Original
Message-----
From: Ed Anderson <eanderson@carolina.rr.com>
To:
Rotary motors in aircraft <flyrotary@lancaironline.net>
Sent:
Mon, 25 Jun 2007 10:34 am
Subject: [FlyRotary] Re: Method of killing
power??
Good point, Bill. Mine will slowly leak down through the
pressure
regulator, but not fast enough to preclude potential flooding
with a
leaky injector. But in my case, "Plugs Up", any fuel that enters
the
combustion chamber simply drains out the exhaust port(on the bottom)
and since the plugs are at the highest point, there is less likelihood
of any liquid gas entering into the spark plug cavity and drowning the
plugs. This is the reason why flooding is not a significant event for
the plugs up.
Ed
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