On 24 Nov 99, at 16:46, HealerHand wrote:
> One of the reasons that vortech have to use cast
> curved impeller is because the impeller is much
> smaller than ATI's. Smaller impeller will make less
> PSI at a given rmp. Therefore, vortech must use
> curved impeller. ATI uses T-56 Billet design.
> Although the curved impeller can produce more boost
> (increse air flow) but casting????. Casting is an old
> technology. Billet is grinded (CNC) from a piece of
> material.....ATI impeller is one piece material..vs.
> vortech is two pieces..... Second note: vortech is
> very popular amoung the cobra owners, but popularity
> doesnt mean is better...
The strength of the impeller would only be an issue if Vortech
impellers were flying apart all the time. The are not, so it obviously
is plenty strong enough. The reason ATI doesn't make a modern
impeller design is because it is a lot cheaper to make a straight-fin
billet impeller than to properly cast a multi-piece impeller as
Vortech does. Lots of turbo impellers are made the Vortech way.
Also, all jet engines are made with individual blades attached to the
turbine hubs. They spin faster and are many times larger in
diameter, so the forces on them are probably 100 times higher (or
more) than on a Vortech or ATI. Beyond that, they must withstand
very high heat. Even so, they are the most reliable type of internal
combustion power plant around.
I am not sure what you are getting at talking about smaller
impellers. The bottom line is that the Vortech design makes more
boost for a given amount heat generated (and power drained from
the motor). It just plain works better. That's why the ATI design
MUST have an intercooler to avoid destroying your motor.
As for casting being an old technique, I guess it is, but that doesn't
mean it's bad. BTW, all those swords and spears that were made
5000 years ago and more were all...FORGED! I guess that means
forging is bad, too.
Finally, in my last post, I forgot to mention one more disadvantage
of intercoolers: they cause airflow restriction in the intake path,
thereby reducing the pressure and volume of air that gets to the
motor.
Matt Miller
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