Re: Hybrid project

[David Dymaxion <david_dymaxion@yahoo.com>]

I started out thinking I wanted to do a hybrid, but after doing some
calculations decided against it, and am planning to do a pure
electric instead.  I was going to get an Audi Quattro, power the
front wheels with a VW Jetta Diesel motor (I think it would bolt
right into a 4 cylinder Audi), and power the rear wheels with an
electric motor.  I figured I would get 40 to 50 mpg, and do 0 to 100
km/hr in < 10 seconds.  Here are some of the reasons I decided
against it, plus some more recent reasons:

VW came out with their turbo-diesel.  I was going to be lucky to do
as well.  It does 0-60 mph in about 10 seconds, and is EPA rated
about 40 mpg city, 50 highway.

The batteries add alot of weight, which fights economy and
acceleration.  (Bolder batteries and/or supercapacitors may change
this for the future.)

Powering the rear axle with an electric motor would not allow gear
changes for it, necessitating high gearing so it didn't fly apart,
making acceleration and regen braking poor.

The motor would take up most the room up front, so the batteries
would have to go in the back, tending to make the car tail heavy. 
The vehicle would be at stock weight already, so battery weight and
electric motor weight would decrease the payload.

Motor size is a smaller effect on fuel economy.  The car's size and
weight are a much bigger effect.  If you look at the EPA figures for
almost any vehicle, the 4 vs. 6 cylinder fuel economy is not very
different.  Also, very small engines tend to have poor efficiency
(for the power produced).

By joining the list and reading and calculating, I figured a pure
electric would provide about 95% of my transportation needs.  I could
use a 2nd ICE car for the remaining 5%.  I have come around to the
opinion the best hybrid is a 2nd car.

A series hybrid multiplies its losses.  You get all the losses of the
generator, and then the losses of charging the batteries, and then
the losses of powering the motor.  I think a parallel hybrid, where
the electric motor boosts acceleration, is a better idea.  Dodge,
Toyota, and Honda are doing parallel hybrids.  Just for a
counterpoint, Al Cocconi does a series hybrid, but only uses the
charging trailer for long trips.

The Honda Insight is a technical tour de force, but I'm actually not
super impressed.  I bet if you did that much lightening and aero work
to a regular CRX, replaced the 4 cylinder with a 3 cylinder, you
would get similar fuel economy and acceleration as the hybrid.

A couple of caveats:  I am interested in good acceleration, and don't
spend any time sitting in traffic.  For areas with heavy stop-and-go
traffic, I can see a hybrid would greatly reduce smog.  Make all your
1st gear starts electric, and then cruise on gas power for higher
speeds would greatly reduce traffic jam smog.

--- Ken Trough <ken@digd.com> wrote:
> ...
> I am aware of the various commercial projects by the manufacturers,
> and a
> few concept type vehicles, but are there any decent hybrid systems
> around
> that are home buildable?  I am actually considering doing this to a
> 1979
> corvette if I can get the numbers looking good before I begin. 
>...
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