Scott Speirer wrote:

Paul,

Writing with some more questions about the stock turbocharged 13B's.  I haven't
bought one yet, but once I do, I'm hoping to match the engine with the right
turbocharger(s) and control(s) to normalize the engine for altitudes up to about
15,000 ft.  I'll use the methods put forth in Hugh MacInnes book "Turbochargers" to
estimate what would be required.

1.  What model turbochargers were used in the late model year 13BT's?  Any one
particular year would be fine.  I'm hoping that the particular brand and model number

are commonly know, so that I can look up it's compressor map.  I'd like to know what
Mazda was comfortable with.

 
Are you referring to the 93 and later? Those are dual sequential turbo's and probably 
unsuitable for aircraft use. I have no idea what the turbo maps look like. The 89-92 
single turbo II's appear to be the best choice as they are similar to a Garret TO-3.
The main 
drawback is the waste gate area may be inadequate for high altitude and higher TIT's 
could be used with a real TO-3 equipped with an Inconel turbine wheel and an external 
waste gate. I suspect the pop off valve is used in cars to deal with a sudden 
throttle closure. 

2.  What kind of control, or controls were used with the turbocharger of 1.?  Was it
a waste-gate valve or blow-off valve?  What were the minimum and maximum compressor
boost pressures was it set for?  I'm hoping to find out what the maximum intake
pressures the engine was designed to handle.

I don't know the answers to these questions. The 89-92 has a simple pressure
servo connected to the intake manifold and waste gate and I think it regulates the
boost to about 5 psi.

3. Was any kind of intercooler ever a part of the stock installations?

Yes. All stock turbo models had intercoolers and they are required to reduce the 
possibility of detonation. I would monitor the intake manifold temperature
and limit it to around 140 degrees F or so. I don't know the exact temp
that would result in detonation.

4.  I'm wondering how to calculate the gas flow rate for the engine as a function of
engine rpm.  I know the displacement is about 1300 cc's, but is this 1300 cc's per
revolution, or 3 x 1300 cc's per revolution?  How many revolutions for a complete
cycle?  (I'm kind of embarrassed because I think these are the basics behind the
engine, and I should know better.)  :)

For purposes of calculating the required airflow consider the engine a four cycle
of 2600 CC.

If information like this isn't easily available to you, could you point me in the
right direction to find it out?

Thanks for your time,
Scott In Phoenix

 
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