Mark Steitle wrote:

<snip>

Paul,
I like the Lamar pump, but I'm not sure that's the best route to go for
me.  I have the ample room under the cowl for the stock pump and I was
planning on putting a second alternator on the plug side of the

engine.  I

was contemplating switching to the 13B housing to trim a couple of

pounds

from the fwf weight.  Do you know if there is any difference in the

n/a 13b

water pump housing and the turbo housing?  The reason I ask is that the
impeller on my 20B pump is .150" larger dia. than the n/a 13b pump
impeller, but same height.  Does the 13B turbo use the larger

impeller or

the same impeller as the n/a engines?   It looks like the two impellers
could be swapped if necessary.

Mark S.

They are not for everybody. If you have the room you don't need it.

That larger impeller is the first I have heard that had a different

diameter.

That could be a real problem down the road when you might need a new
cartridge.

I have seen subtle differences in the cartridges however. Different shaped
impellers and different volumes of cavities around the impeller over the
years.

They all seem to be interchangeably. I would love to see info from
Mazda engineering on what things they have tried and what changes were
made and why. I know the 3rd gen pumps are bought from Kaboto Tractor.

Tell me if you see something that looks like your pump.

Also please take some pictures of your pump and send them to me.

Paul Lamar

<snip>
Paul,
My impeller is cast iron, like the first and last pictures, not stamped
steel.  The diameter of my 13B unit is 2.590", whereas the diameter of the
20B impeller is 2.760".  Height appears to be the same.  Seems to me that
the 20B impeller would be an improvement for the 13B folks.  The
interesting thing I discovered is that the machined bevel in the 13B
housing is the same size as in the 20B housing, indicating that the 20B
impeller would fit in the 13B housing.   I'll send pictures tomorrow.

Mark S.

Have you tried buying a 20B water pump cartridge? I was wondering what it
cost?
It would be easy to machine the water pump housing for the larger
impeller if it were readily available. I am just a skeptic when it comes
to the 20b because so few were made so long ago. If Mazda goes back
into production it would be just great for aircraft use.
Certain parts could be manufactured for the after market such as
a cast 20B intermediate housing  and the e-shaft if there were
enough demand but I don't think the water pump cartridge  would
be among them.

Paul Lamar

Paul,
I'm hoping the 3rd gen 13b turbo impeller is the same as the 20b.  Can
anyone confirm/deny this?

Mark S.

No the third gen impeller is entirely different and so is the housing.
The pump might fit however.

Paul Lamar
 
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