Leon Promet wrote:
Hi Guys,
Just thought I'd drop in my two bob's worth.
The only reason an engine will break an apex seal is if it is either
severely under lubricated, the engine if fed a solid object, or the
engine detonates. The only reasons an apex seal slot will wear out is that
it has insufficient lubrication and/ or the engine has been ingesting
abrasives.
We have already done the lubrication thing to death, so if you have
disconnected the oil metering pump, and you forget to put 2 stroke in your
fuel after all the discussion, then serves you right.
A decent size oiled foam air cleaner pod, ( http://www.uniflow.com.au/ )
serviced regularly, will stop the ingestion of all foreign material,
unless you are extremely careless when working on the engine with the
cleaner removed. (And I just know some bright spark is going to pop up out
of the ground and say you don't need air filters on aircraft!!. I can just
feel it in my bones!!).
DON'T EVER run a rotary without an aircleaner!!. They hate a diet which
includes ANY sort of "roughage". Feeding solids to rotaries hasn't ever
done them one bit of good. Just one handful of dust on takeoff and you
have a VERY sick motor. Don't risk it. Don't leave the ground without
one!!
As for detonation, well, you just make sure that the air and water and oil
are kept cool with a decent sized intercooler, radiator and oil cooler.
Additionally, use the correct fuel, don't run too much advance,
especially on the trailing under boost, and don't run too lean under
boost. If these precautions are met, I can't see why the engine should
ever detonate. If it does, it ain't tuned properly!!
The stock REW engine, with the 2 mm, 3 piece seals will put out 350 BHP
without the cats and mufflers for days on end, and all that @ about 9 lbs
boost, as long as you keep the sucker COOL.
So make sure your radiator, oil cooler, and intercooler is big enough to
keep the engine cool on the hottest day you can imagine you will ever fly
in. I'm building mine to be fully functional in 50 deg C heat! We
regularly get 35 ~ 37 deg C days here in Sydney during the Summer, and it
gets worse as you fly west into the centre of Australia!
I'll be using a Series 6 REW engine, 9.7:1 compression Series 5 rotors,
Slotted to 3mm and the CAREFULLY rebalance the WHOLE rotating assembly.
(Again, some theoretician is bound to pop up out of the woodwork and tell
me it's not necessary). The better you balance a rotary, the smoother it
becomes, like any motor. You have to experience it to appreciate it.
Anyone who has will know what I'm talking about. All the theoreticians
won't.
I'll be using Mazda factory 2 piece 3 mm seals.
(1202-11-300A/1202-11-302). The 1202 seals are bulletproof, the quality
is superb, and they are LOTS cheaper!. I will admit that I have absolutely
NO personal experience with the Hurley seals, but until I have a problem
with stock ones, I'll stick with them. Apex seal weight only becomes a
problem at RPM well above the operational range we used in an aircraft
application. (Not much over 6,000 PM).
Each complete security overhaul (700 ~ 1000 hrs) will then cost me less
than $2,000 AUD in bits (a little over a grand US). All that I envisage
will need replacing are apex seals and end pieces, corner seals, oil
control "O" rings, a full set of springs and gaskets and water "O" rings,
and a front & rear stationary gear.
After the second overhaul, I'll just recycle the engine into a car for
road use, and build a new one. Anyhow*, by the time I've done a couple
of thousand hrs in the air, second hand Renesis engines will be readily
available from Japan at reasonable prices.
So that's my admittedly very biased, prejudiced, one eyed view on these
things. You don't need to mess with all the fancy stuff.. If it ain't
broke, don't fix it!! The engines are just wonderful as they are!! The
only dud part that Mazda make is the black outer oil control "O" ring, and
it looks like that problem can be solved cheaply by McMaster-Carr.
Cheers,
Leon Promet
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