The big problem is the several airplanes powered by Power Sport
P-port
engines don't show up at the big air shows and they don't race. Is
something wrong?
In the good old days Everett Hatch and Allan Tolle would show up at
most
large air shows. Allan would blow everybody away in the time to climb
and go 238 MPH in the Sun 100. Everett untimely death set us back at
least 10 years and maybe 15 at the rate we are going.
Paul Lamar
Matt Prather wrote:
Is there a longevity cost on a p-port engine? Other than turning it
faster (which isn't directly a problem), are there any problems with
the rotor seals?
Regards,
Matt---
Nobody has worn out a rotary yet. Fractured apex seals from detonation
yes.
Swallowed bolts yes. Lost all oil and engine failed or caught fire from
bad plumbing
or bad oil coolers yes. (many times). Lost all coolant and had to land
yes.
(several times) But nobody has worn one out yet.
Paul Lamar
Paul Matt,
There has been some assertions to that on some web sites, even Francois is
under this impression.
I personally believe it stems from the racing game where extremely high RPM
where PP's excel, do wear our engines faster. As well as the factors of
detonation etc.
However at our RPM range and conditions it's only breathing better.
In fact I think the blast of fuel and air on the apex seal helps to keep
them cool. Wasn't that why the oil injection was directed at the centre of
the Apex seal, to cool the hottest part of the seal!
George ( down under)
When Mazda won the Leman 24 hour race race they disassembled the 2" p-port engine and
and attempted to measured the wear. They found NO discernible wear as the
dimensions of the parts were within the manufacturing tolerances of the parts.
Here is an RPM histogram. This engine generated 173 HP per rotor Normally
aspirated. In two rotor terms for the arithmetic challenged that is 345 HP.
Francisco Iannette told me using his ceramic apex seals the projected life
of the engine was 20,000 hours in constant speed generator service based
on a several thousand hour test and by measuring the apex seal wear very
very carefully.
Star Mazda rent a spec race cars run for several 10 race seasons without touching
the engine. These cars are now within two seconds of the lap times of
five times more expensive Toyota Atlantic cars and use dead stock RX8 engines.
Failures if they do occur are caused by external factors. However
lots can go wrong. Missed or inappropriate shifts can force over revving.
Apex seals run at 500 degrees F or higher. Dirty oil will wear the seals
faster. Over heated oil will break down. Mobile one full synthetic I happen
to know for a fact due to my own test will withstand oil temps twice what
non synthetic oil will withstand. Failure of the oil injection pump and plastic
oil lines is common in old Mazda street cars. That is usually the cause of
the demise of street cars. You see many old RX7's with over 300,000 miles on them.
That is not to say apex seals do not wear. They do but it is difficult
to get any sort of handle on that as you would probably have to run
several engines for well over 3000 hours in typical aircraft use
in very controlled conditions to find out. Tracy ran his first engine
for 950 hours as I recall and due to a design flaw in the Ross gear
box it failed the Mazda e-shaft thrust bearing so he had to rebuild
the engine. He opted for a more powerful version. I saw the apex seals
and they were far from worn out. I did see a little wear on the sides
of the seals but I think Tracy was not running 2 cycle oil in the fuel
at that time. He was using Marvel Mystery oil. My test indicated that
MM oil was less than well suited for lubing apex seals with a low break
down temp. The bottom line is we don't really know the life of the engine.
Could be for the rest of your life.
Paul Lamar
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