Miata Mailing List: February 1996, Message #107
sponsored by



     


   From: Brian Goodwin 
Subject: Autorotor and Exhaust? Clutch?
   Date: Fri, 2 Feb 1996 18:52:45 -0500

Hi, day three with the autorotor and the clutch is already slipping.
        
        Finally got a chance to drive this thing on dry ground last night.
I drove around and around on some of the less populated roads in the area.
The power is REAL.  Hit the gas at 20 or 30 and suddenly you notice yourself
passing the 100 mark on roads marked 35 before you know it.  I had planned
the necessity of a clutch but did not think it would wear out as soon as it
is.  I have done NO HARD launches from a standing start and the clutch is
already slipping.  I notice it now only in third gear in the high RPM's but
obviously it won't last long--just too much power for the poor thing.  I
would appreciate hearing from those with performance clutches and charged
engines on their thoughts regarding clutch selection and performance.  I am
thinking I will go with a Centerforce Dual Friction model.  Comments?
Suggestions?
        On Noise--Had many questions on this and I have to change what I
reported earlier.  Why?  Because my earlier reports were with the top and
windows up because of rain.  The noise question had a different answer with
the top down.  With the top down there are two distinctly different sounds.
You hear the supercharger whine that you expect.  You also hear much belt
sound--just the belts running.  Some of this may be because I have yet to
replace the plastic pan--more sound is getting out or reflecting off the
ground?  Neither sound is loud enough to annoy me but I may put a Scosche or
Dynomat hood sound blanket on someday.  Then again, I have driven it much of
the time with the radio off focused on listening to it.  When I turn the
radio on I don't hear anything from the supercharger--and I don't play my
music especially loud.  Hope that helps everyone who asked about this guage
the level of sound.
        Another thing I would like to gather the wisdom of the miata list on
is exhaust selection.  I have had good luck before with a local shop that
has done work on my other project cars so I will probably go to them.  As
for design I am thinking a 2.5 inch from the cat back.  Does anyone think
this is too big for the volume of gas from a 1.8 supercharged engine?  If
they have any larger cats lying around from a recent custom job on a big
inch car I may have them put it in (a cat designed for a V-8 Firebird, for
example, will flow a much higher rate than the stock miata unit and the car
will still pass smog.).  
        From my experience I want a straight through design muffler.  I was
originally thinking an ultraflow exhaust with only the necessary bends to
relocate the spare tire under the car (ala Candoo).  I have had good luck
with these before.  However, when I told the guy at my shop that I want it
as quiet as possible with as much flow as possible he suggested I go with a
CVX unit.  I have read excellent reviews on the CVX "constant velocity core"
muffler but never heard one on a miata.  Has anyone out there used one of
these?  Any other suggestions?

Brian