Re: Stuperchargers

[jafo@tummy.com]

In article <m0vfsW8-000BpXC@insti.physics.sunysb.edu> you write:
>I always thought that non-turbo superchargers (;-]) are most noticeable
>at the low rpm.  This is what they're going to tell to J.Q.Public. Btw,
>doesn't VW Corrado come with a non-turbo supercharger?

I seem to recall hearing that the Corrado came in a "traditional"
supercharged configuration.  The late first-gen MR-2 also came
this way.  Superchargers are just like turbos with one exception...
The supercharger is always running, so you don't get turbo lag.
This also means that you are using up more petro because the
supercharger is always dragging the engine down.

Of course, a turbo constricts the exhaust, which doesn't help mileage
either.  However, Saab claims that their turbo cars are actually more
fuel efficient than a non-turbo engine producing the same power.

You can get somewhat around the supercharger inefficiency though.  You
can bypass the supercharger (so it's just churning air instead of
actually compressing it) which reduces the load and reduces fuel
consumption.  You can get power back as quickly as the gate can be
closed, so it doesn't have a huge lag either.

>On a related topic: I recall hearing that turbochargers can be balanced
>(uh, that's a bad word, I guess... fitted, adjusted) to a certain rpm
>range.  Could somebody explain what's going on in one paragraph? ;-)

The change various parameters about the turbo, including the size and
weight of the turbo.  A smaller turbo takes less time to spin up, but
also doesn't produce as much boost.

Enter the system like the third-gen RX-7 has.  You have a turbo tuned
for lower-end power and no lag, and one tuned for higher-end power.
There is a gate in the exhaust that selects which one is being used.
I've never driven one, but the people I've talked to who did
really liked that setup.

Sean
-- 
 I used to think that the brain was the most wonderful organ in
 my body.  Then I realized who was telling me this.  -- Emo Phillips
Sean Reifschneider, Inimitably Superfluous <jafo@tummy.com>
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