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(named: ) turbo/super



>     I'd love to hear any arguments you might have in
> favor of a
> supercharger, particularly with regards to our cars.

1) instantaneous throttle response (no lag)
2) perfectly linear throttle response
3) easier plumbing (no manifold changes necessary)
4) easier CARB certification (if you're a mfgr)

Personally, I would generally recommend a turbo for
nearly any real forced-induction project. You're right
about the majority of situations. Here are two cases
where there are exceptions to your argument.

1) Superchargers are easier to deal with and support
as a manufacturer. I would argue that Neuspeed or
Jackson racing has far fewer "customer complaint"
(what I might call "customer stupidity") issues than
Greddy. The fact that boost levels are not directly
related to crankshaft speed creates a LOT of issues
that the average person can't deal with and tune for
properly. Wastegates, fueling, timing, etc. are all
more difficult to manage when you cannot directly tie
air consumption to engine speed. Couple that with the
millions of stupid people out there, and you see why
there are relatively few mass-produced turbo kits.

2) The reason I personally am going with a
supercharger is due to the intended purpose of my
vehicle: autocrossing. The nature of autocrossing
means that instantaneous throttle response and a
linear torque curve are FAR more important than
efficiency and maximum power potential. I'm wondering
how in the world I'm going to get 200whp hooked to the
ground...300whp in a 1900lb car on an autocross would
be completely unmanagable and slow me down. I also
need to be able to apply power whenever I want, *NOW*.
There are people who are pretty successful at planning
in advance for turbo lag on an autocross, but it is
definitely not an ideal situation. If they make a
slight mistake in their timing, it costs them several
tenths of a second to correct, then potentially a
second or more to get the boost back up. That's the
difference between an easy 1st place and 10th at a big
event.

Additionally, having a direct relationship between
throttle position and power output is a huge
advantage. I've talked to enough Supra drivers to
understand the issues created when you're navigating a
long-ish sweeper or a slalom at part throttle in a
big-boost turbo car. Just about the time you've set
the car up nicely for the turn, and balanced the
brakes, throttle, and steering on the head of a pin,
20psi of boost comes rushing in to mess it all up! At
3500rpm a Supra might make 150whp...but 1/2sec later
at 3600rpm it could be doing 350whp! There is NO
in-between. Managing that situation definitely takes
time/attention away from driving faster.

And on top of it all, my rough calculations indicate
that, presuming the same intercooler size/location, a
G60 setup is probably at least 15-30lbs lighter than a
turbo. The G60 itself is only about 15lbs, there's
much less plumbing, no extra manifold weight, no
wastegate (well, the bypass valve on the TB weighs a
few ounces, I suppose), etc. When you rely on light
weight to beat 600hp AWD cars, 30lbs does matter. 

Just another perspective on life... :)

Neal

=====
~Neal

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