Bulent Aliev wrote:

"I took my (ex Rusty's) turbo apart this evening. The

bearings seem to be in

fairly good shape and the shaft looks ok. It looks like the

compressor wheel

just "came off the end" of the shaft, much like the other one did.

My

uneducated guess would be that I overspeeded it.

By the way, I was showing 38 MAP at 11,500 ft with the

wastegate fully open.

However,  there's an open 1/2 inch air bleed on the intercooler

(to be

closed off) and a blow off valve, so the turbo may have been

putting out

much more than the MAP showed.

John Slade
Rotary Cozy IV"

This is not making much sense Bulent. 38" Hg MAP with the waste
gate wide open AND
a 1/2 inch hole in the intake manifold? Something is wrong with
these "facts".
Does John have a TIT or TOT gage? It is possible the turbo is
over speeding
due to no load on the compressor but you would not see 38" Hg
IMHO at the same time.
Are you sure John has a 90-91 turbo and not a 87-88 turbo?

Dave Leonard please check and see if you get 38 MAP at 11,000
feet with the
waste gate wide open. Briefly! :)

Paul Lamar

My experience is that this is reasonable (although probably not with a

1/2

in. hole in the intercooler).  I refuse to go higher than 35"MAP
intentionally for the time being, but my experience is that having the

waste

gate open does very little.  On the ground it seems to make no

difference.

I run the stock waste-gate controller only for some sort of auto control

to

help prevent boost creep.  In other words, I set the MAP using the

throttle

then look away and do other things.  My hope is that the waste gate will
help prevent significant creep past that set point.

Coming up in the next few weeks will be some flights with the w/g open

to

see if there is a change.  I will see what I get at 11k, but I can tell

you

that it will highly depend on RPM.

Dave Leonard

I don't have time to write a treatise this morning, but sounds to me like
the turbine and wastegate are both undersized for our application. This
would make sense for a car; what you want is instant boost response. To do
this you would undersize the turbine and make the aspect ratio on the
housing pretty restrictive. In our application you want a free flowing
turbine and larger housing to reduce TIT and increase efficiency. I have had
good luck dealing with Turbonetics. They aren't afraid of strange
applications and have done all the turbo work for Mazda racing. You might
try swapping housings to one with a better aspect ratio, but to get it right
sounds like a new turbo.

Monty

There is a trick to make the turbine look larger.
Drill a bypass hole up stream of the turbine about here.
I hesitate to recommend this as it is non reversible.

Paul Lamar
 
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