Re: A4TQ ECU Upgrades

["David G. Lawson" <dbldmnd@compuserve.com>]

Hi MIke,
I have read the article about 4 times now and there isn't enough
information presented to determine what they did and why the results are
the way they are.

The premise for the article is a head to head test of 4 ECU chips from
Wetterauer, Tap, Hoppen(MTM or Abt?) and Ams(Abt?). They performed dyno
runs at Jackson Racing(Honda place) on a dynojet 248-C, 0-60 mph timed runs
and 50 - 70mph pulls in 3rd gear. The outcome was the Wetterauer chip
logged the  highest HP and torque with Tap 2nd, Hoppen 3rd and AMS last. 
All had some good improvement and the Hp numbers were within 1HP of each
other. The peak torque varied by 30 ft-lbs.Wetterauer took 1st, Tap was
2nd, Hoppen was 3rd and AMS was 4th. The curves varied quite a bit so a
single number doesn't tell the whole story. Tap had the lowest 50-70 mph
time and AMS had the best 0-60 mph time. The confusing outcome was the chip
with the least improvement has the best 0-60 time. The author  didn't dig
into this and they basically shrugged their shoulders. 

My questions include, what car was tested? They say it is an Audi A4 1.8
turbo, that is a start. The article mentions driving a quattro with the
modified ECUs in the LA rain and how well it grips through the corners, but
a few paragraphs later they talk about coast down tests on a FWD model
which show an 8 percent drivetrain loss. Then they mention the 3000 rpm
launch technique using the clutch. So I would think they used a manual car,
but they never give a concrete answer as to what drivetrain, FWD or
quattro, was used. I would guess that a FWD was used, since I am not aware
of dynojet making a 4WD dyno. If a FWD was used, that could explain the
best 0-60mph by the chip with the lowest improvement. Maybe the FWD
configuration couldn't handle the increased torque, and wheelspin was
encountered, but the antislip regulation (ASR) steps in doing its control
thang and pulsing the front brakes, thereby slowing the acceleration to 60
mph. If this is the case, it is a good argument for using the quattro
system to distribute that newfound power. But I didn't have to tell anyone
here that. Does anyone know if a light comes on or something else to notify
the driver that the wheels are slipping, and the ASR is stepping in to
"help" out? 

They also didn't mention which gear the dyno runs were performed in.
Scanning the porsche list archives, there has been some discussion about
needing to perform these tests in different gears 3rd, 4th and 5th in order
to get the correct amount of loading for turbocharged engines to develop
its maximum boost. It seems that 4th gear is correct for the 944 turbos.
The article also makes no mention of the boost levels these chips were
running. 12psi, 14psi, 16psi? Check out that tiny KKK-KW03 turbo, think of
1 bar boost, and contemplate PV=nRT. If the stock K26 is starting to loose
efficiency at >2.0PR, that KW03 can only be making heat out there.  

They also never give the details of the car tested. They say is was a stock
1.8T, but what size wheels/tires are on the car? It comes standard with
195/65/15 and 205/55/16 as an option. An article sidebar talks about the
225/40/17 tires installed on the long term test car. Since tire size
effects gearing, it would be nice to know this and then using the 3rd gear
ratio(1.429) and final drive, you can back out which RPMs cover the 50-70
mph pull. This is of interest, since 3 of the torque curves fall off
rapidly after 4500 rpm. BTW what is the final drive used in the manual 1.8T
models, quattro and FWD? C&D in Feb 97 list 3.70 for the quattro, but I
don't think this is correct. Maybe a 4.11? I do think the 1.8T has a
different ratio than the V6.

I believe they used the same car for all these tests and just swapped ECUs.
They make no mention of the dyno testing procedure, all 4 done on the same
day? 1 each day? How did they deal with intercooler heat soak?

They do mention the pinging encountered with the hoppen and wetteraur
chips. I too wonder how the knock regulation works and why it takes 40km of
driving for the ECU to realize that knock was encountered. Another point
the author made was how the hoppen chip "maintained boost" between shifts
and the others didn't? Since the stock 1.8T has a bypass valve fitted, when
the throttle is closed, turbo outlet boost is routed back to the turbo
inlet so this helps all the chips maintian boost between shifts. I would 
guess that the hoppen chip has massively advanced timing for part
throttle/off-boost conditions allowing the engine to speed up faster, this
could also explain the pinging encountered.

All in all, an interesting comparison. More info would be nice. All should
get the mag and read it a few times. The hp and torque curves are
interesting. It might be another good example of "more is not always
better".
-
Dave Lawson