Group, One source of easily adjustable waste gates is turbo motorcycles.

There was a excellent

poppet valve waste gate on the Yamaha 650 turbo. The bike used a

diaphram actuated by inlet

manifold boost to open. The standard opening was at about 5-6 psi

manifold pressure. The trick was

to put low pressure regulator in line, and viola! instant dial a boost

with a max of about 12-16

psi manifold pressure. Bill Jepson

-Barry Gardner wrote:

The low-buck racing crowd uses this trick, too. They buy an aquarium air
valve and splice it into the hose that senses the boost. This valve is
opened slightly as if to allow to a slow leak, which tricks the control into
thinking the boost is less than actually generated by the turbo. Voila! The
boost is increased.

Here are the traps, though. A brass aquarium air valve is a
less-than-precision instrument, shall we say, and vibration can make it
loosen to allow overboost. Racers put nail polish on it to cement it in
place after determining via the dashboard boost gauge how much boost they
want to allow. But even allowing for "calibrating" and controlling the air
valve, the real problem is that all that extra boost has to be accompanied
by enough extra fuel. If you boost too much and lean out the engine, boom.
At least, that's what's reported.

You can also enrichen your mixture by fooling the on-board computer into
thinking the car is colder than it is. When the car is cold, the computer
increases the mixture just like a choke on a carb car. Racers splice a
potentiometer like a speaker volume control into the wire between the
radiator temp sensor and the computer and then can fool with the temp signal
the computer receives. Again, it's not exactly a calibrated tweek.

But now we are seriously off-topic. Aviation is not a friendly place to mess
with such solutions, clever and simple though they might be.

I'm not a racer and have no first hand experience. However, I read a lot of
posts on the Turbo 2nd Generation list from www.teamfc3s.org.

Barry Gardner
Wheaton, IL- 

That reminds me. If you use a microcomputer to control the waste gate
a whole host of parameters can be used to control the boost.
Intake manifold temp being the primary one but coolant temp, oil temp,
RPM, etc., etc., etc., can be used to insure the engine does not detonate
and/or is not over stressed in any way.

Paul Lamar
 
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