Turbo vs. Supercharger.

[slash2 at mindspring.com (Scott Rose)]

Actually the company that makes them went out of buisness I believe.  I had
a nice talk with Corky himself about these turbos.  He had said it was a
great design.  But the problem is it ended up kinda like beta max vcr's.
You can still get get them, but expect to pay for one as well as a rebuild
at about 50,xxx to 70,xxx miles.


At 10:22 AM 02-07-03 -0700, you wrote:
>> I'm not completely
>> sure exactly how it works, but from what I have been
>> told there is a nozzle of sorts that is constantly
>> varying how much exhaust flows into the turbo.
>
>Sheesh! Another self-proclaimed forced induction
>zealot who has not read his Corky Bell books! Man, you
>guys need to get with it! <grin>
>
>http://www.aerocharger.com/
>
>They sound like they'd be really cool. Mr. Bell
>recommends these very highly. But from what I've
>heard, they're quite expensive. I have no experience
>with them outside of the Bell books...never seen one.
>They either must be REALLY expensive, or there is some
>disadvantage that no one is mentioning. Or maybe their
>marketing department just plain sucks!
>
>I have a few comments, with regard to altitude
>adaptability: The "turbocharger vs. supercharger"
>debate really isn't as such. It's really a matter of
>the manner in which they typically control their
>maximum boost levels, NOT the designs of the
>compressors themselves. Turbos use a wastegate (or
>similar) based on a set maximum pressure.
>Superchargers usually simply calculate the maximum
>boost they want (which requres picking a starting air
>density), and put on the pulley that gives them the
>required charger RPM.
>
>However, turbo bearings, like those on a supercharger,
>DO have a maximum RPM, and they do reduce efficiency
>when you approach it. If a turbo is set to achieve the
>maximum boost possible within it's efficiency range
>and within the redline RPM of the bearings at sea
>level, then it will exceed these parameters at a
>higher altitude. In the best case, you take a
>significant hit on efficiency. In the worst case, you
>wreck your turbo! The wastegate wouldn't know the
>difference, or care. Eric's big "turbo advantage" only
>works when the turbo is operating well within design
>parameters at sea level, with enough headroom to spin
>faster at higher altitudes without blowing up or
>running off the efficiency charts. So a production car
>does receive this advantage, but modified turbo cars
>running higher-than-stock boost should be very careful
>at altitude!
>
>A variable-diameter supercharger pulley that could
>vary RPM independant of engine speed would not be
>terribly difficult to design. This would compensate
>for various altitudes, just like a turbo, and could be
>built to guarantee that you wouldn't exceed the
>maximum RPM of the charger. However, the advantages to
>a production car probably aren't enough to warrant the
>additional cost/complexity, and a race car team would
>find it much easier to simply change pulleys when they
>race at altitude.
>
>Neal
>
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Scott Rose
88 red 16v
Import R  "solid shift" linkages for VW A1 chassis
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