Boingers

[Raymond C Drouillard]

On Thu, 7 May 1998 09:42:03 +0100 Robert Humphris
<r.humphris at indigo-avs.com> writes:
>The point with the Wankel is that it is a 1.3, where as a Camaro is
>what, 3 times that displacement? Yet they have similar performance.  Add
>that to the weight of the engine, which does add to the performance of
>the car ( less weight = better power to weight ratio, and better
>handling as the car ceases to be engine heavy, so you start getting
>easier moments of force on the car ).
>Lets compare like for like, I guarentee that if you added sufficent
>number of rotors to take the displacement to that of the Camaro, fuel
>injected it, you would be unable to out drag it.  Then if you take the
>same displacement as the Saturn ( What is one of these we don't have
>that model over here in the UK ) and put it in a similar weight car,
>that the engine would be just as lively, and the performance would be 
>as
>good if not better as the weight would be less.
>
>Two stroke direct injection engines?  We will see what they are like
>when they are mass produced.
>
>Rob Humphris

I'm not really trying to trash the Wankel.  It has characteristics tha
make it useful in some situations.

I purposely ignored the whole displacement issue.  If I created an engine
that I could put into a Hummer and make it perform like a Camaro and get
30 miles per gallon, would you be impressed?  Would it matter if the
engine was a ten liter engine?  I know that it wouldn't make a bit of a
difference to me.  If it weighed more, it would make a difference, but
not enough for me to discard the idea.

When you're rating different designs of engines against each other, you
can't use something like displacement as a measuring stick.  Let's treat
the devices as black boxes.  We look at what goes in, what comes out, and
its physical size and mass.  While we're at it, let's look at how long it
lasts.

We find that the Wankel has a better power/weight ratio.  All other
things being equal, that would definitely give the Wankel the edge,
especially in applications where weight is a big concern.

The Wankel doesn't shine at all in the gas consumption ratings.  It is
acceptable, but not great.

When it comes to maintenance, the Wankel really falls down.  Granted, you
can get it to last with some special techniques.  In most of the
discussions I have seen, however, the discussion was about how to make it
last long enough to win a race.

The average driver wants to put the key in the ignition and go.  He might
be bothered to take it to the local Minit-Lube for an oil change once in
a while, but he certainly doesn't want to be pouring 2-stroke oil into
his gas or anything like that.  In fact, I was told by an engineer that
the reason that production cars don't use water injection is because they
don't want the drivers to have to use more than one consumable liquid.

So, we find that the Wankel is useful in some applications.  A few people
put them into experimental aircraft because weight is a real issue in
aircraft.  Reliability is an even bigger issue, so it's going to remain a
VERY few until the engineers manage to get the Wankel to be reliable in
the long term.  I'm not holding my breath because they have had quite a
few years to work on that issue.

We see them used in racing because the engine only has to last one race
and fuel consumption isn't a big issue.

One car company is putting them into a production car, and that car is
selling enough for them to keep making it, but not enough for them to
attempt to use the engine in a bunch of other models.  Nor are the other
auto manufactures making any plans to use it.

Why is that?  It goes back to my earlier message.  When you look at the
whole vehicle, you find that there aren't really any improvements.

WHen you choose a car, you realize that you have to give up gas mileage
to get performance, and vice versa.  If the Wankel would let you have
both (the power of a Camaro with the mileage of a Satuurn), the cars with
that engine would sell like hotcakes.  As it is, what you see is a car
with an exotic engine, average performance and fuel consumption, and some
reliability problems.  When the salesman tells you that the engine is
lighter than the Camaro's, and only displaces 1.3 liters, you might say
"Gee, that's impressive" and go buy something else.

Ray Drouillard

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