RE: Sad reactions to S4 drive - experienced turbo drivers please help (very long)

["Peter Berrevoets" <peterb@mysysltd.com>]

My (long gone) Mazda 626 turbo 2.3 20V I4 - introduced me to this, as well
as experience driving a Saab 900S and the infamous Porsche 930 turbo.

The torque steer on both the Mazda and the Saab made them a handful under
full boost but with practice and experience it simply becomes a coordinated
backing off the throttle progressively as boost comes on. Much like letting
the clutch out as you apply more gas when one first learned to drive
standard. You jerk it around a bit and then you have that "Aha!" experience
where it becomes second nature - until you drive a 911 Carrera S with a
racing clutch and it's jerky time again :-)

The S4 brings so much power to your right foot that things feel like they're
happening too quickly... bet you get used to this real quick and will never
want to drive a lesser beast again.  LB!

HTH

Peter
1990 200TQ - don't have to worry about too much power here!


-----Original Message-----
From: owner-quattro@audifans.com [mailto:owner-quattro@audifans.com]On
Behalf Of Avram Dorfman
Sent: Tuesday, September 21, 1999 5:56 PM
To: quattro@audifans.com
Subject: Sad reactions to S4 drive - experienced turbo drivers please
help (very long)


(this was cross-posted to www.A4.org/forum/s4.html)

Ok, I've just had my first drive in a 00 S4. It was at Inskip in Warwick,
RI. Let me be clear on the purpose of this post:

I am airing my feelings & intepretations based on my limited experience
with turbos, in hopes that more experienced turbo drivers will tell me they
originally shared my feelings, and then tell me how they got over it.
Ultimately, I'm trying to re-build my excitement for the S4 I've ordered
that's supposed to be here next month.

First, let's be clear: the car is magnificent. Make no mistake. I'll say no
more about the positives - if you've read them, I agree with them. If you
haven't, read the S4 forum at A4.org.

Now here's the issue. There are "two parts to turbo lag." This car
certainly has *less* lag than any other turbo I've ever driven, save the
stock 1.8t.

The first "part" of lag is the minimum RPM. This is basically a non issue
in the S4 - with peak torque at 1800 rpm, you slip the clutch a little in
1st, and you're done. It's easy to stay above 2k once you're moving.

The second part is the time it takes the fan to spool up when you hit the
throttle. It seems this is an issue at *any* RPM. It certainly was in the
5ktq's I've driven, and that was my fear when I ordered an S4. Basically,
if you're just cruising at a constant speed, at say 3500 rpm, and then you
punch it - it's about 1/2 to 3/4 sec before you get the boost.

In my experience you have to pay this penalty *every time you lift the
throttle*. That is, every time you shift, and every time you've stopped
accelerating, even if you didn't shift. This makes sense to me b/c the fan
is powered by exhaust pressure, and when you lift off the throttle, you get
minimal exhaust.

Now I have to admit, part of the problem may be this: What people are
saying about the shifter being vague & having long throws is right. It was
taking me probably 1/4-1/2 sec between throttle-off and throttle-on to
accomplish each shift. I'm sure this amplifies "lift-throttle lag" (did I
just coin a new term?).

So, my question for all you out there who drive turbos all the time is
this: Is this something that you just accept & get used to? Or are there
techniques that you learn which avoid lift-throttle lag? Am I going to have
to get used to a 2 stage acceleration curve on *every shift at any speed*?

If there are techniques that defeat this problem, please explain them. Do
you "second guess" the power, and get back on the gas *earlier in the
shift* than you would in a non-turbo? Or do you flat out *not* get off the
throttle in the first place? Sounds bad for the engine - over revving... Or
do you somehow lift the throttle "less" than you would in a non-turbo?

What about chipped 1.8t owners? I've driven unchipped 1.8ts, and I find the
lag totally acceptable. Now I don't believe the *duration* of the lag is
any shorter, I believe it's that the amount of additional thrust you get
once it's over is small enough that you didn't really miss it while it was
gone. This is just my guess - I'd like to hear more experienced accounts.

If there is anyone in southern New England with a chipped 1.8t who'd be
willing to take me for a ride, I'd *really* appreciate it - I'll buy you
dinner & return the favor in whatever I end up with (seriously).

What it boils down to is this: When I step on the gas, I want power "now",
not "later." So far, I find it unpredictable - I press the gas until I have
the power I want. Then the power doubles 1/2 sec later, and now have *too
much* power, so I lift throttle. Guess what happens then? That's right - no
exhaust pressure, so now I lose *too much* power. It's a constant game of
"too little - too much".

I've been driving a del sol VTEC for 5 years. This care technically only
has 120 lb-ft of torque, but with an 8200 redline & reduced gearing
compared to most cars, this car effectively has 160-200 lb-ft (I'll spare
you the math; post if you want to see it). So, it's not crazy to compare it
to an S4. Now the power-band in the del sol is 6k-8k rpm. Of course I don't
just drive around at 6k, so the penalty I pay is I have to shift if I want
power. But with a normally aspirated engine, you always know how much power
you're going to get - it's (RPM * throttle position * gear). With the S4
and any other turbo, I find that there's a whole range of power levels you
might get at a given (RPM * throt * gear), depending on what the previous
throt. pos. was, and how long it's been since you changed it, *and* the
effect is different at different RPMs.

At this point, I'm very seriously considering going back to an A4 2.8, and
getting a supercharger. I'll miss the Nav system & the 6-speed, but I can
take care of the rest. Is there anyone in southern New England with an SC'd
A4/2.8 that would take me for a ride? Again, I'll buy you dinner too &
return the favor... My big concern on the SC is that apparently it's really
loud. You just can't win 8-)