Forced induction project

["Michel Drainville" <MDrainville@xxxxxxxxxxx>]

Can it be done?

I am in search of a project for my car.  I would like to install a
centrifugal blower on my 91 318.

Why a centrifugal blower instead of a turbo or a positive displacement
blower?
Well, it's simply because I want to custom build my setup and the turbo
will be too much trouble to install. The M42
engine has a wide head (16valve) and is tilted toward the right side (inner
fender), where the exhaust header is
installed. Doing a custom header would require to remove the engine to be
able to weld and measure accuratly. I
simply don't have enough time for that kind of project.

Also, a positive displacement blower, like the one sold by Downing Atlanta,
is what I would like to have but it
represents a too big investment considering the year and value of the car.

So, since I'm a do-it-yourselfer, and I like to do custom work, I was
thinking of the following project:
To take a used/rebuild turbo possibly from a MR2, remove the impeller side
(exhaust), and use only the compressor
side and the bearing/bushing housing with oil lines. Then where the
impeller blades were, install a pulley and
fabricate custom brackets to mount it on the engine.

But before I start doing that, I would like to have the advice of people
who have experience with forced induction.

The first thing I would like to have advice on, is about the side loading
of the shaft. In a turbo, the shaft is
supported in the center and the two impeller at each end load the shaft
with an equal force, I suppose. In my setup,
the end of the shaft with the pulley on it will create a greater side load
because of the adjustement of the compressor
to keep the belt tight. Are the bearing capable of such a load?  Will the
impeller eventually touch the housing with bearing wear??

Second thing, is about compressor size vs speed. A turbo seems to have a
smaller compressor that the one used in a
centrifugal blower if I compare them using the size of their housing as
comparison. So, since a pulley driven turbo,
will turn slower than a exhaust driven one, will I see some interresting
boost figure? I'm not looking for 25PSI but
something in the range of 5 to 10psi. I will start with 5 and if everything
works fine, I may install a thicker head
gasket or head spacer and raise the boost higher, while monitoring injector
duty cycle, oxygen sensor and air flow
meter and correct these as needed.

Does it sound feasable??

Tanks
Michel Drainville
91 318ic

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