<Misc> Supercharging

[Kennedy Simon <Kennedy.Simon@xxxxxxx>]

A while back I promised a report to the digest on the results of my
supercharging research.  Unfortunately this job-thing has really gotten in
the way, so I'm going to be a little less thorough than originally planned.

I'm also going to ignore the Super vs Turbo debate: I chose super for
linear, predictable boost.  Lots of good reasons to go w/ a turbo instead,
especially if you need >400HP.

To me, the choice came down to ERT's Vortech kit or Dinan's Powerdyne.  Both
cost around $6K, both are bolt-on kits, both pomise around 350HP.  I know of
a couple of club-racers who have had failures w/ their Powerdyne blowers
(the powerdyne is an internal-belt drive centrifugal blower using ceramic
bearings and air-cooling).  When the *internal* belt fails, it corrupts the
bearings and you need to re-build the unit.  So I was interested in the
Vortech (gear driven, oil-cooled) for its greater reliability, but concerned
about the higher sound levels.

Dinan offers a 2-year warranty, Vortech/ERT 1, neither warranties racing
usage, both will continue to operate (ERT/Vortech w/ a special chip) if the
blower fails.  A survey of 3 Dinan SC customers failed to turn up anybody
who had racing experience or a blower failure (unlike ERT, Dinan drills
extra cooling holes in their powerdyne blower.  ERT simply recommends you
buy the Vortech if you're going to be spending real time on a track).  I
still felt the Vortech was the more reliable unit (Chuck Stickley uses one
and had had no failures that I know of with it and a whole lot of wins).  I
also like the ERT electronics better (Jim C @ work).

So the only question for me was noise.  I test drove a Vortech-equipped M3,
and would describe the sound as a sort of irritating whine, v. similar to
what you'd here on your radio if you had a poorly shielded power cable
running near your speaker leads, but only audible below 1500 RPMs w/ the
radio off; above that level the noise totally disappears (stock exhaust).
After 2 days, it has somehow become less annoying and for some reason kind
of cool.  Not, it turns out, an issue.

The dyno numbers on my car w/ SC are: 259 ft-lbs torque, 314 HP, @ the rear
wheels (that's 313/380 @ the engine, using a 1.21 correction factor).
There's a parasitic loss of about 2 HP below 1800 RPM - from then on up it's
all gravy, and above 3K the car is insane.  Serious wheelspin going into
second.  Much fun.  The torque curve is actually flatter than stock, and
overall the car just feels like a couple more cylinders have been added.
Haven't had it on the track yet, but can hardly wait.

Well - in a nutshell (if an incoherent one - it's been a busy week) that's
my report.  Feel free to post me questions if you're interested, and
sometime later this week, or maybe next, I should be able to try and answer
them.

Simon Kennedy
'95 M3
ERT/Vortech SC
Lightweight flywheel
HD clutch
H&R Springs/Bilstein Sports
RD Sway bars
X brace
Eibach strut brace
Floating rotors
SS BRake lines

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