I've been told by some Mazda enthusiasts that the single turbo 13B
developed
230 hp in the US. This is plenty of power for my needs. Can anyone refer
me to specific model years I should look for? I do know the twin turbo
13B
developed 280 hp but I am also concerned this might be too complicated for
aviation use.
Thanks,
Rick
A 1990, 1991 to 1992 are good years but you will to do something to make
the
turbo live. I think Dave Leonard has his turbine trimmed down and a larger
compressor installed. If you don't slow down the turbo some how the
turbine
has a life expectancy of only a few hours in aircraft service.
--
Paul Lamar ...No rotor no motor.
With this in mind is it possible for me to contact Dave? Perhaps more
importantly, what about a completely different turbo?
My perspective is that the OEM turbocharged engine will be a conservative
system and therefore a good foundation. However, with your fatalistic
response I'll have to make sure I understand the issues well before
finalizing any decision.
Can anyone else here educate me regarding why aviation use degrades the
OEM
turbo so quickly?
Thanks,
Rick
With this in mind is it possible for me to contact Dave? Perhaps more
importantly, what about a completely different turbo?
My perspective is that the OEM turbocharged engine will be a conservative
system and therefore a good foundation. However, with your fatalistic
response I'll have to make sure I understand the issues well before
finalizing any decision.
Can anyone else here educate me regarding why aviation use degrades the
OEM
turbo so quickly?
Thanks,
Rick
OK let me explain it to you. Automotive turbo chargers are designed to
accelerate
quickly for car acceleration purpose. F = M x a. Therefore a = F/M if you
want a lot
of "a" you need a a lot of "F". In an automotive turbo charger this
happens for only a
few seconds at a time. Most of the time the turbo charger is loafing. Not
so in an aircraft
engine. To run the compressor at a constant speed you don't need a lot "F"
(read HP).
Now the force on a turbine blade tending to throw it off on a tangent from
the hub
is F = m x V^2/r. V is the speed of the blade as it travels around in a
circle. m is the mass
of the blade and r is the radius of the circle. Pretty soon the force on
the blade exceeds
the strength of the blade and the turbine disintegrates. So what you
need to do is load
down the "F" with a larger compressor or cut "F" down by trimming the
blades. Adding
to all this of course is the high heat of the exhaust which weakens the
metal the turbine
is made from.
This is fundamentally why un-modified automotive turbo chargers are not
suitable for
aircraft use.
On the up side it is possible to mix and match turbo charger parts. For
example: larger
compressors fit on given turbines slowing down the turbo charger while
generating
the same amount of boost. This reduces the V (RPM) and the turbo charger
last longer.
Of course the turbo charger no longer accelerates quickly but you don't
care
about that in aircraft engines.
Paul Lamar
Dave Leonard,
Will you please publish the exact specs on your turbo, for us less bright
guys to copy? I want to go into a turbo shop and tell the assistent: "Give
me a turbo with these specs, please."
Erik.
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