Miata Mailing List: February 1996, Message #20
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   From: Brian Goodwin 
Subject: More on the Autorotor
   Date: Thu, 1 Feb 1996 16:44:43 -0500


Hi everyone.        

        Got a ton of e-mail with questions about the autorotor.  Because I
have to get a project out at work today I will not get a chance to answer
everybody's questions until this weekend--But I promise I WILL answer
everyone's questions as best I can by next week.

        What are my first impressions?  
                In brief here they are.  This unit changes the whole
character of the car.  If you decide on this one be prepared for it to feel
and sound totally different.  The unit itself makes more noise than either
the Sebring or the Aerodyne turbo cars I have driven.  That said the sound
is not necessarily objectionable.  The car is not really louder, just different
sounding.  It is a bit disconcerting at first but I found myself quickly
getting used to the new sounds-and liking them.  

        At just off idle rolling speed it just sounds like you have a custom
exhaust on--a low tone rumble-like sound to about 2500rpm.  If you drive
with a very light throttle the car sounds almost stock from about 2500 all
the way to redline (no, the boost is not always on like the silly Sebring
negative advertising suggests and a few people have asked me about.).  If
you hit it so the supercharger engages you hear a superchager whine and the
total sound impression is not unlike a Mazda rotary. (And if you don't like
the sound you can just add a dynomat hoodliner from any good stereo store
then hear just your exhaust burbble.)  Unfortunately yesterday it was
raining hard so I can't say too much about performance yet--everytime I hit
it I broke both
tires loose on the wet ground.  
        The only time I was able to really lock up was a couple of times
this morning on the way to work.  I even surprised my first Mustang.  He
pulled up on my right a block before the left turn onto the freeway
obviously intending to beat me to the ramp.  The ground was half-dry because
of a break in the rain and I heard his tires chirp when the light went green
so I hit it after a rolling start from about 2000rpm.  Luckily the tires
held this time and away I went shooting right passed him (got a feeling more
tire and a new clutch will be sooner rather than later).  He got off the
same exit when I got to work and asked me at a light if I had a mustang
motor in it (guess he knows what a monster miata is).  Sure was fun.  
        Early impressions are that it feels much like the Sebring from 2000
to 4000   When you get to 4000, however, it definately outruns my seat of
the pants impression of the sebring.  (If you hit the gas before you
disengage the clutch you get boost instantly but I have not been able to
lock it up this way yet.)  Regarding 4000 rpms--once you get to about 3800
you better know where the car is pointed because you will be there in a
hurry.  I have only had it above 4000 three times but enough to know it just
rockets from there on.  It is nice having real torque down low.  The dyno
showed an AVERAGE rear wheel torque (as opposed to the higher at-the-crank
numbers) of well over 140 measuring from 2000 to redline with a VERY FLAT
TORQUE CURVE.  I already notice I drive it lower in rpms now because I can.
It feels stronger at 2000 to 4000 than it did stock at 4000 to 6000.  
        While it undoubtedly makes more power than the other kits out there,
it is not without tradeoffs.  The installation of the Sebring is definately
a cleaner looking setup that runs quieter and can be installed easily by the
do-it-yourselfer.  On the dyno the Sebring only shows 125 to 130hp at the
rear wheels while our final dyno numbers yesterday for this otherwise bone
stock miata were 156.3 hp at the rear wheels (not at the crank like the
factory quotes--116 for 1.6 liter, 128 for 1.8 liter etc. but at the wheels
where a stock 1.6 makes about 98hp and stock 1.8 liter makes about 108.). So
you have to decide what you want more--ease of installation and quiet
result---or tough installation and a more dramatic result.

I will give a much more detailed report later after I have had more
opportunities to drive it on dry ground.
        
Brian

ps. I did NOT install it myself.  I have done this kind of work before
(installed a sprintex lyschom screw unit which is very similar on a Mustang)
but my work keeps me too busy right now and frankly I found the instructions
to this kit daunting.  I started the work anyway but after the car was on
jack stands for two weeks because I was at work I got tired of waiting for
my schedule to clear up and decided it was just better to pay to have it
done anyway.  I put all the stock stuff back on and drove it to Mechtech in
Escondido California --619-432-0555.
        Mine was the fifth Miata they have done (they also do the Aerodyne
kit).  They have a first class dyno and far more experience than I.  Corky
recommended Mechtech and I found they gave great service--with the dyno
tuning an added super plus!  I would recommend them to anyone.  You want to
talk with Jim.  If you go tell em I sent YA!