X-Mozilla-Keys:                                                                                 
Jeff Spitzer wrote:

Paul wrote:
I gradually open the throttle to keep the
manifold pressure the same as I climb and at
30,000 feet the air density has fallen from
about .0019 pounds per cubic feet at sea level
to .0011 at 30,000 feet. At this point
I would need a pressure ratio of only 1.72 to
maintain sea level pressure. This appears to
be a peice of cake for this turbo. A max
pressure ratio of 3:1 appears to be
available. Paul

You've mixed density ratio and pressure ratio here.  The pressure ratio to
maintain S.L. MAP to 30K is 3.37.  the density ratio you cite is also
screwy.  The actual density ratio is more like 2.67.

I knew you were going to say that Jeff about the pressure ratio :-)
Yes but after you correct for pressure you need to correct for
temperature. My intuition says the real situation is in the same 
direction as the density ratio.

Yes I did screw up the actual density ratio number. Sorry.
I used .0019 instead of .0022 for sea level. I think it is
closer to 2:1 rather than 2.67:1. Just reading it off the
chart. PL

Bill Wrote:
I also wonder if there are any compressor stability
problems that might occur since at TO you would
have the compressor running max effort against a
substantial restriction.  Any possiblity of a surging
problem with this under these conditions? Bill

The charts show surge line.  Don't get anywhere near it.

Bill wrote:
A simple butterfly valve made of SS321 in a thick walled
tube well downstream (lower temps) with a manual control
via a throttle valve would seem more elegant and less likely
to burn extra fuel and the turbine wheel during the most
common condition - less than max altitude. Bill

I tend to agree with Bill that you need some other control for your stated
mission.  Maybe just an adjustable throttle stop that limits motion in the
go-around scenario.

Jeff Spitzer

Now your talking. I am going to run this whole no-waste-gate turbo 
scenario past Bob Keller at Turbonetics later this week.

BTW an ordinary  dyno would be near useless for this type of situation
as
you need cold intake air and cold air flowing through the intercooler
and rads.

A dyno/torque meter built into the motor mount would be a much 
better investment.

Paul Lamar
 
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