> 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.
We have been through this discussion quite extensively several times.
Please check the archives for further details.
Truth is that there is a wide range of turbos that would be acceptable.
Your choices of PSRU, desired boost, cruise altitude and space under the
cowl will all play a role in the turbo selection. But many will work.
The overriding rule is "Make it big" and let it loaf.
In my installation, the only manifold that will fit is the stock
manifold, so I am limited to the stock turbine housing. Given that
restriction, here is my solution:
Stage IV upgrade to the '91 turbine housing:
http://www.bnrturbos.com/2ndGen.htm
I then cut out the wastegate flapper all together, creating a fixed
exhaust bypass. That still allows me to make all the power I want (45"
MAP at S/L) but reduces the back pressure on the engine and stress on
the turbo. If you want more power, you will need to keep the wastegate
flapper.
An equivalent off-the-shelf TO4 would be cheaper, but the manifold then
becomes an issue. Garrett made a bunch of cast iron manifolds if you
can find one (with and without external wastegate mounting). I don not
recommend the SS manifolds that are so prevalent, unless you find a way
to support the weight of the turbo separately.
I will be giving a talk at the rotary roundup this year detailing the
options and my trial an tribulations.