Mark Waldron wrote:

Paul,

    I've been concentrating on the NA version of the 13B for my eventual
project (due to cost and weight), but it seems worth at least considering a
turbo.   I don't need more HP for sea level conditions, but the extra power
at alt (especialy for low density altitude takeoffs) might be useful.

    So, some questions for those in the know:
    - If I recall, many have written that with the turbo they believe they
can get by with no muffler.  If so, what's the approx weight diff (turbo+no
muffler vs. NA and swiss or tangential muffler)

I would say it is on the order of ten or twenty pounds in favor of no turbo.

    - Pluses/minuses of the stock turbos

Low cost.
Could over speed due to the small size of the turbine. Strict attention
to the turbine inlet temp as the material may not be Inconel
as is available with certain after market turbo's from Garrett.
 

    - Cost, recommendations in the aftermarket turbos

$750 and up for the turbo. $250 and up for a manifold. Then you will
need a intercooler and piping. You might get away with a stock Mazda
intercooler if you have room.

    - Set-up considerations (waste gate, etc).

We are rapidly coming to the conclusion that a waste gate is not
essential with a Mazda as the engine is very robust indeed.
Fly it by the boost gage. No cylinders heads to blow off through 
the sides of the cowling. The stock second gen 89-91 (best years to use) 
has a built in waste gate.

    - Reliability issues:
        -- What are the typical turbo failure modes, esp relative to safe
continued flight under power.

The big thing to avoid is knock. That can crack an apex seal.
Other than blowing them up from over speed turbo's have a benign
failure mode. The blades slowly melt or erode off the turbine wheel reducing
the boost and the power and the heat energy applied to the turbine wheel.

        -- Just how often do they fail (If used primarily for turbo
normalizing vs boost above SL/standard day conditions)

If you limit the power they could last thousands of hours. 
On the other hand we have no hard and fast data. It will take 20 
years to get enough turbo rotaries flying to come up with some 
average life. No question about it. You will be in the experimental 
stage in every sense of the word. PL

Thanks to you or any who care to reply.

Mark Waldron

 
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