Date: Sun, 17 Apr 94 22:04:56 EST
Subject: S4 Turbo adventures

Well, I finally have my '83 Ur Quattro back on the road with its new
"S4" turbo.

I have to agree with Glen that upgrading to the "S4" turbo is probably
the single best thing you can do for your Ur Quattro (and probably, by
extension, for the 5000 Turbos as well??). [This was your sentiment,
wasn't it, Glen?] It completely transforms the character of the car --
from an overweight slug [well-mannered and with excellant handling
though it may be] which couldn't out-accelerate a crippled turtle [OK,
OK, I exaggerate a *teeny* little bit, it probably could beat a crippled
turtle, if by no other means than by sitting on it and squashing it!]
into a reasonably potent "GT" [in the classic "Grand Touring" sense or
tradition]. It still ain't no Sports Car (although with fat sticky gum-
balls like 225/50 Yokohama A008R's it could give my Lotus a real run for
its money in steady-state cornering "g" force), and by no stretch of the
imagination is it a "muscle car". But I am no longer embarrased by every
clapped-out Nissan Pickup at a stop light . . . (I don't know what it is
about Nissan pickups and Audis [or at least *my* Audi], but they're e-
verywhere, and they seem to relish stomping on my Audi! Hah! No More!]

   * * * Boost is a Wonderful Thing * * *

(Of course we all knew that anyways, right kids?)

As low as 1750 rpm, the turbo will build up about 3-4 psi of boost (it
takes a couple of seconds), about 4-5 psi by 2000 rpm, around 9 psi by
2250 rpm, and by 2500 rpm it is fully pegged at 11-12 psi of boost, which
it maintains until well past its power-band (e.g., 6000 rpm). The engine
really "comes on the cam" at 3000 rpm, and pulls strongly until around
5000 rpm where power starts dropping off; by 5500 rpm it is clearly past
the fun part, although still pulling; by 6000 rpm it is clearly well past
the optimum shift point... [By contrast, the original turbo -- admittedly
past its prime and not in the best of health -- didn't even *think* about
boost until 3000rpm, when it would grudgingly yield up 3-or-so psi of as-
sistance]

Spool-up times for the turbo are also much improved (to be expected with
the much smaller exhaust turbine on the "S4" turbo). Worst-case times
(throttle-off coasting down, engine pulling full 24-or-so inHg) are about
two seconds at 2500 rpm to 11 psi boost, circa second-and-a-half at 2750
rpm, a tad over a second at 3000rpm, and maybe half-a-second at 3500 rpm.
Cruising under power (engine pulling about 8-10 inHg), times are roughly
halved (about a second at 2500 rpm, around half-a-second at 3000 rmp, and
darn near instantaneous at 3500 rpm). Mildly accelerating (engine at about
0 inHg...), response is half-second at 2500 rpm, and virtually instant at
3000 rpm and above. (I also bought the Audi/Abt "dash" with three extra
instrument slots (holes), one of which got a 30-inHG-to-15-psi-boost VDO
guage - boost guages are fun to play with... By the way, if you go this
route, I suspect that the little 20-degree-angle boots you can get for the
guages would be well-considered, they are definitely far-enough-right to
clip the left-most edges of the guages' ranges)

Zero-to-60 times appear to be in the 7-9 second range. I should qualify
this by saying that first, it's hard to watch my wrist-watch, the tach,
the speedo, and check over my shoulder for merging traffic while clutching
and shifting and wondering if there's a cop in those bushes all at the
same time, so "accuracy" is somewhat vague. I should also admit that,
not wanting to pay for a new clutch every weekend or so, I don't do the
6000-rpm-and-drop-the-clutch-screaming-starts routine, I get the car
moving and clutch fully engaged first then "punch it", which means I lose
at least a second (maybe two) to not only spooling up the turbo, but get-
ting the engine into its power band -- the engine is a real dog much below
2500 rpm or so. (I will also parenthetically note that in the lower gears
[especially in first] that the 3000-rpm-on-the-cam power-surge [Gods, I
*never* thought I would use "power-surge" and "Audi" in the same sentence!]
can be quite dramatic -- to the point that in any sort of "dynamic" (by
which I mean "not-in-a-straight-line") handling event, the drama could get
quite Dramatic Indeed! I wonder if I can spin this sucker . . .) It seems
to take forever to get to 3000 rpm in first from a standing start . . .
then like Right Now it's at 6000 rpm screaming Shift-Me-Shift-Me-Now-You-
Fool. A pleasant change . . .

Oddly enough, even though "completely stock" (in so far as the engine
is concerned -- i.e., cam, wastegate, etc.), the wastegate has decided
to modify itself and regulate at 11-12 psi of boost, rather than the
6-8 psi "original" performance. This is high-enough that the computer
decided it was OVERBOOST-time-to-shut-down time, so the computer had to
be diddled a bit ("you just stick a resistor here in this green wire")
to keep the ole fuel a-flowin'! Much of the "raw performance" increase
is of course due to the enhanced boost; but the "quality" of the perfor-
mance (i.e., building up boost "responsiveness" a good 1500 rpm earlier)
is due to the "S4" turbo and its smaller [quicker-to-respond] exhaust
turbine. Adding water-cooling is a nice fringe benefit . . .

Sure wish I had this setup when I drove the car up Pike's Peak! (On the
other hand, maybe I would just have killed myself with one of those
surprising it's-3000-rpm-time-to-switch-on-in-the-middle-of-a-hairpin-
turn-at-10,000ft-above-anything rushes now available.)

Of the three guages, the second is a water-temp gauge (well, the new
upper engine-block hose outlet with the water-fitting for the turbo
had all these other holes that had to be blocked, and a water temperature
sensor is as good a "drain plug" as anything...). I'm curious if anyone
else out there sees the same behaviour I do. While crusing down the road,
it holds at a nice steady 185-190 (F). However, just tooling around town
(or even just sitting and letting the engine idle), the temperature shifts
to hold at around 230-240 (F), a little lower if actually moving around
as in traffic, but a solid 230-240 sitting in a parking lot. I can see
(hear) the radiator fan cycle on, the temp drops 10 degrees, the fan
turns off, the temp rises back, the fan switches on, etc. and so forth.
Now, this does tend to explain the observed phenomenon that, during win-
ter (say, 20 (F) or below), at idle the heater can keep the passenger
compartment nice and toasty, but "on the road" I need a sweater to stay
warm . . . anyone else see this? Can anyone explain why Audi puts the
thermostat at the bottom of the block in the EFFING COLD WATER INLET
FROM THE RADIATOR rather than at the top of the engine where the water
gets hot? Sheesh! Oh well, another classic German Idiot-Savant Engineering
example.

Now, I suppose you're gonna ask how much did this all cost? Hey, if you
have to *ask*, you know . . .

I had all the work performed by Dave Clark and co at "The Benz Den" in
Belmont, MA, (617) 489-6548. These guys are *GREAT*. They really know
Audis (/German cars in general), and the Ur Quattro in particular. And
they're friendly and fun to talk with as well (obviously not factory-
trained!) I *HIGHLY* recommend them to any Eastern-Mass-type Audiphile!

The final total was - round numbers - $4500. Figure $500 for the new
dash and three VDO guages; another $1500 (plus-or-minus $500) for all
the other stuff: new vacuum hoses all around (won me back 2 inHg at
idle, and 4-6 at high-rpm-coast-down!); two new engine mounts (out of
four - and for once the cheap two, not those damn expensive hydraulic
mothers); fuel pressure regulator (this won me back 500-1000 rpm on
top end! apparently it was "over-regulating" -- mostly "erratically-
regulating -- and killing overall system pressure; new injectors (Hey,
all five now match! Sigh; so much for Audi factory-trained mechanics
and Audi dealers...); and other such assorted miscellanea. The turbo
was $1000, and nearly another $1000 for all the assorted bits'n'pieces
that connect to the turbo (oil and water feed and drain plumbing, all
the bizarrely-twisted-with-different-sizes rubber hoses for the air
tract, etc and so forth). [If you add up all the parts' prices, you
realize they gave me a FANTASTIC deal on labor! And they spent a *LOT*
of time working on the car, mostly trying to diagnose all the strange
little failures like "Why does it stop running at 5000 rpm"].

So -- if your Audi is otherwise running perfectly -- start at $2000 for
the parts, and go from there. (Audi wants $1900 for the turbo, some
place in Florida "could get one from England" for $1600, Ned at Intended
Acceleration wants $1300 for his; I got mine for $1000 from Northern
California Turbo (800) 950-8872 (ask for Brad -- they now have several
("half a dozen, plus parts to build several more") in stock. They had
to order mine from KKK/Germany [didn't even take six months!], so they
"stocked up").

The turbo is basically a bolt-in replacement. As delivered from No.Ca.Turbo
the compressor housing was rotated 60degrees from "original", but trivial
to pop the bolts and rotate the housing. The compressor inlet was about 1/8
inch larger in diameter than the original, but the new rubber hose slipped
on readily enough. The stock 5000 turbo oil and water lines bolt right in
(while EFFING EXPENSIVE -- over $200 each on the oil lines!!!!!), they fit
exactly in place and are much easier than trying to fabricate new fittings
(the old oil lines will NOT fit the S4 turbo). Replace the water outlet
atop the block with one from the 5000 Turbo w/taps for turbo water return
line (and water temp sensor, and a few other things too???), tap into the
block lower freeze plug for coolant into the turbo (next to actually get-
ting all the parts, this was probably the trickiest part, and it was very
straight-forward for anyone with the tools...), and just bolt the new turbo
in place. With the exception of the freeze-plug krock, it looks like a fac-
tory design (which for most intents it is...).

Now, about those Intended Acceleration computer mods and 15psi wastegate
springs . . .

					-RDH