Variable Compression, Variable Displacement you decide

[Roger Heflin]

> 
> >Again same as above.  The auto books I have read say the biggest problem
> >with a supercharger is how much power the use at high rpms.  This they
> >say is the only disadvantage of a supercharger over a turbo.
> 
> This has been my perceptino as well.
> 
> Turbos offer much better performance in the mid-high end of the RPM range,
> simply because they have to spool up based on lower exhaust pressure at
> lower RPMs.  Superchargers, being belt driven, and most of the time driven
> by a 1:4 or a 1:8 gear-up system, right off idle are making boosted power.
> The problem with superchargers, as you said, with a 1:8 planetary drive
> (for example), your engine sitting at 6000 RPM, your blower is spinning at
> 6000 * 8 = 48000 RPM.
> 
> It comes down to application - for a street car with not so high RPMs (lets
> say, around 5k or so), a supercharger is great.  Turbos tend to be better
> for road racing and/or tracks of that sort.  Of course, there are millions
> of exceptions.
> 

It occurs to me, that you could make an electric supercharger (big one not
the little ones some have now) by putting a generator where you would 
normally put the supercharger, and then putting an electric motor
with the blower part elsewhere.  With a bit of control in the electronics
you would probably be able to boost the low end (over a supercharger,
way over a turbo) and keep the high end from getting too excessive.  I
figure that doing things this way would probably boost the cost of
a blower kit somewhere around 1500 (big enough generator/motor pairs and
the control stuff get expensive).  It may boost the cost more, but
it would be alot more adjustable on the fly, even computer controllable,
ie knock avoidance by reduction in boost.   It would give the computer
to adjust both the boost and the advance to be optimal for power, or
fuel efficency.   I know turbodyne makes small electric blowers, but
as far as I can see they don't produce the necessary pressure at
volume at wot at higher rpms, so only boost the lower curve, which
with some engines (that have bad lower curves) would be a bit help,
but not on larger engines for any kind of racing.


			Roger Heflin