From: "John Slade" <sladerj@bellsouth.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Subject: Turbo thoughts from Leon
Date: Tue, 13 Jul 2004 08:26:38 -0400
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Leon Said:
As for your turbo problem, are you running a blow off valve? There was
some scuttlebutt on the newsletter about them. FWIW, BOVs (Blow Off
Valves) are only meant to relieve excess pressure caused by sudden rapid
closure of the throttle - a situation fairly unique to cars. They are NOT
meant to control boost pressure - that's what the throttle and waste gate
are for.

In an aircraft situation, the manifold pressure should be WHOLLY controlled
by the throttle. There should not be ANY need for a waste gate apart from
wanting to be able to "normalise" (maintain constant manifold pressure for a
given throttle setting) the engine, if the engine is so set up for that -
which most auto turbo installations aren't. With the Hi-Flo mods, the Mazda
turbo is quite capable of making 360 + BHP @ 12 - 15 PSI. That's a pressure
ratio of about 2:1, which is well within the capabilities of the basic
unit. Even @ 10,000 ft, running 38 " MAP, you are still within that
pressure ratio envelope.

So I can't see why a Mazda turbo won't work, unless it's not set up
correctly. The lack of a muffler and exhaust restrictions WILL allow the
turbo to produce more boost and flow more exhaust gases, but as mentioned
above, the boost level is always at the mercy of the throttle. If the
throttle is not open, you don't get any boost! Anyway, again, my two
bob's worth.