Jmorrisonbc@aol.com wrote:
Anything I've written on rotary engines has been my opinion, based on
experience I have had myself. Obviously, there will be differeing opinions,
and that's the great part about forums such as this right?
I, unlike those selling rotary engines to pilots, have nothing to gain either
way, so my opinions are in the spirit of "food-for thought".
I want to make something perfectly clear and that is: the Aircraft Rotary Engine
News Letter is not selling rotary engines to pilots or any one else for that matter.
Nor do we accept advertising. Any links you see on our web site are there as
a public service only and we are not paid to put them there. I run the newsletter
strictly as a hobby. I am fed up with the cost of aircraft engines and I think
the rotary engine is a better way to go. I just paid $100 for a dip stick for
my Continental O-470 as it was lost in shipping. Lycoming exhaust valves are
$250 each!
I notice my comments were labeled "ignorant" in a recent posting..
That was not me!
.the
gentleman who wrote the posting obviously feels very strongly about the
rotary engine but it is a shame that he feels compelled to call other
aircraft enthusiasts "ignorant".
There is no shame in being ignorant. One should however educate oneself
before holding fourth.
If I exaggerate (and I did with the
reference to dirt in the oil passages) or if I'm just plain wrong, I'm man
enough to admit it when the contrary is proven, but I'll refrain from
personal attacks. I don't mind being called "wrong", but don't call me
ignorant OK?
The Mazdatrix website is very familiar to me, as I referenced it often in my
attempt to save my 12A from the wreckers (didn't I mention I spent a year
trying to rebuild my rotary, and have had conversatons with every supplier in
North America?). They sell rebuilt engines with all new parts assembled with
care and expertise. The twin turbo 13B engines, which conceivably could put
out 200hp, run for just under $5000 (less core charge).
Again that is probably Canadian money as new engines can be had in the States
for $3000 U.S. dollars. Most people buy Japanese engines out of Japanese cars
as there is an inexplicable requirement in Japan to change the engine after
30,000 miles. don't ask me why. The cost can be $1500 and up. Some engines
found in US junk yards can be as little as $500. New rotor housing at
$400 each and seals total cost parts and all would be $500-$800-$900
about $2200 US dollars. Contrast that with a half run out aircraft
engine for $6000 to $8000 and a new A/C engine for $18,000 to $22,000.
The twin turbo engines put out a lot more than 200 HP. The latest versions
are up to 260 HP stock while meeting strict fuel consumption and emissions standards.
The drag racers typically get 700 HP turbo charged with a two rotor.
There is also a three rotor version available with a third more HP.
A new model that will be introduced in the US market generates 280 HP WITH
OUT a turbo charger! Stock! In a street car! Same 190 pound striped weight.
These engines,
however, are not intended for use in aircraft and must still be modified for
that application. The following text is directly from the Mazdatrix website,
and illustrates my point that rebuilding rotary engines has become a very
difficult endeavour, even for the professionals.
**the following from www.mazdatrix.com
Rotary Engines
There are many things that are unique to ROTARY ENGINES (as opposed to piston
engines), when it comes to rebuilding. Many parts can be re-used, assuming
they have been cleaned, closely inspected, and measured to well within specs,
depending on how long the motor is expected to run. Other parts (whose
piston-engine equivalent might have been machinable to re-usable specs.) must
be discarded because they are not machinable. All rotary engine owners should
be made aware that it is relatively "CHEAP" to assemble the most AMAZING PILE
OF JUNK into an engine that will probably run for around one year, have
adequate compression, and not smoke too much.
If a large enough number of these engines are sold, there is just enough
profit margin to absorb the warranty returns, still stay in business, and
write-off the lost customers. WE DO NOT DO THIS! After trying from a number
of suppliers, many years ago, and having only mediocre success (some were
amazingly good at building 13-MONTH MOTORS), we concluded that in order to
control quality, we must build all our engines ourselves. We have therefore
developed our own EXACTING STANDARDS for our engines THAT WE STRICTLY ADHERE
TO.
Please be aware that the world of rebuilt rotary engines has changed
dramatically since the introduction of the RX7. The 1979-85 12A engines are
now over ten years old and have many, many miles on them, and the early 13B's
have not been in a car sold in the U.S. since 1978. We are finding a large
percentage of engines that we disassemble are just plain WORN OUT. These have
very few re-usable internal parts. By bringing in used and core engines from
Japan, and buying local cores, we can supplement the needed pieces, but we
are finding that between two and five engines must be disassembled to have a
good chance of getting a pair of rotors, rotor housings and a set of
machinable housings that are usable. These costs must be added to the cost of
the rebuilds that require the most re-usable parts as opposed to new parts.
Our base rebuilt engines carry a 12-Month Warranty, but are built, assuming
adequate maintenance, to remain in service A LONG TIME. However, we encourage
our customers to take a hard look at the upper grades of rebuilds we offer.
With the added new parts, we are able to lower the number of core engines we
need to obtain, and also lower tear-down, cleaning, and inspecting labor
time. This lets us keep the added cost of the parts well below their normal
selling price, which results in longer warranties and AN ENGINE THAT IS EVEN
MORE VALUE FOR THE DOLLAR SPENT.
Starting with the 1986 engines, MAZDA made a major change in the internal
design of the water seal groove locations. All the 1985 and older engines had
the grooves in the rotor housings. The side housings (front, center, and
rear) need to be lapped smooth for all rebuilt engines, and with no real
tolerances to worry about, they could be blanchard ground and lapped a number
of times (carefully) and still work fine. For all the 1986 and later engines,
the water seal grooves are now in the side housings, which prevents them from
being lapped more than once, maybe twice (very! carefully) before they are no
longer usable. Nobody is sure how shallow the groove can be before the seal
will not compress adequately to prevent water leaks, or seal failure in the
highly stressed areas. We are not willing to be the ones who find out! The
ramifications of this new seal groove location are that usable core engines,
with minimal wear on the side housings, will become a problem (for all
rebuilders) very soon. This is currently compounded by the fact there are few
inexpensive used/dead engines available yet, which makes it very hard to
build up an adequate core ban. This problem is also increased by the fact the
turbo engines are doing major internal damage when they fail. They usually
break the apex seals in the rear rotor (too much boost and/or detonation)
which quite often destroys the center and rear side housings, as well as the
rotor and rotor housing. All of the above is why we need to get the core
engines back for all 86 and later engines, and why the core charge is higher
for them.
**I am responsible for all of the highlighting and underlining, but the text
is unchanged***
John W. Morrison
Mustang Plans-Builder #2051
The engine is NOT hard to overhaul. Many of our readers have successfully done it
after reviewing a video tape by Bruce Turrentine. There is NO machining to be
done. If the rotor housings are OK it is a simple matter of cleaning the parts
and replacing the seals and gaskets. Some people have the side housings lapped.
Tracy's Crooks engine did not need the side housings lapped after 860 hours
of aircraft use nor did it need new rotor housings. The street engines you
see that people have had trouble with are probably due to poor maintenance
such as not changing the oil and filters.
If you are interested in the overhaul process I suggest you purchase the video from.
Bruce Turrentine <BruceTurrentine@aol.com>
919 212-0671
Tracy Crook projects the TBO of the engine to 2000 hours in aircraft service
based on what little wear it had after 860 hours. That engine came from a junk
yard with 80,000 miles on it and it was overhauled by replacing the seals only
before it was installed in the aircraft. No new rotor housings!
I have owned four rotary powered cars starting with a brand new RX2 in 1973 and they
have all been wonderful with one exception. The 73 had what amounted to a head gasket
problem solved by Mazda by a change of material. I still own two rotary powered
cars.
A 1976 13B Mazda Cosmo and a 1984 12A RX7.
All of them have, or have had over 130,000 miles.
I am installing a turbo 13B two rotor in a Kis Cruiser.
Paul Lamar
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