[s-cars] Dragstrip day

Wed Sep 28 23:46:18 EDT 2005

Dave,

That's wierd about the clutch.  While it is not as much power I would run
pretty aggressive short times in the 1.90-1.99 range all night with a stock
sachs clutch with absolutely no problems of slipping in the higher gears.
It was only running a 14.0x-14.2x though with a K-24.  I have seen a couple
of 5 cylinder turbos in Denver approaching low 12's at 112 type
speeds....one of them even a 10 valve turbo.  I think you should have no
problem with your goal of 12's.

--Calvin

-----Original Message-----
From: s-car-list-bounces at audifans.com
[mailto:s-car-list-bounces at audifans.com]On Behalf Of Djdawson2 at aol.com
Sent: Monday, September 26, 2005 6:54 PM
To: s-car-list at audifans.com
Subject: [s-cars] Dragstrip day

Well...
Finally got the car to the dragstrip.  I had my newly installed 928  MAF.
Temps were 81-85 degrees by my dash display, and the dragstrip is at
2700ft.
The runs were made with pump Chevron 91 octane gas.

The results were less than pleasing... but I have to pass them along as
data
points, or I'd be a cheater.

4 runs... 13.13 @ 106.48, 13.23 @ 100.85, 13.19 @ 103.10 and 13.20 @
100.81.

I don't believe I can draw many useful conclusions yet, as the 928 MAF
isn't
adjusted properly.  The car refused to pull hard in 3rd gear, and  somehow,
the early run times (60ft, 330ft, and 1/8 mile) had NO effect on the
overall
time.

My best 60ft time was 1.805 sec.  My worst launch resulted in a 2.244  sec
60ft.  Ironically, the run with the 2.244 60ft was my quickest and  fastest
run,
when it took me nearly .5 seconds longer to complete the first  60ft.  What?
Why?

I discovered A/F ratios were pushing into the mid 13s in 3rd gear.  As  soon
as this would happen, the timing would back off.  I never had a run  where
the
engine would pull hard in all gears.  Very frustrating, and  no way to
adjust
at the track.  From my dyno experience, I know the engine  tends to make its
best power when the A/Fs are in the high 10s when under full  boost and WOT.
Improvement is certainly available here.

Next, the clutch.  The Centerforce isn't up to the task.  You  can't launch
aggressively, or it will go into an uncontrolled slip.  Gotta  do something
about this if I'm going to see good dragstrip results.  Other  cars that
were
making it to 106mph were recording mid 12s on the ET.

Finally, the gear ratios.  Quandry here... 3rd gear at 8500rpm still  won't
get you to the end of the track.  However, shifting into 4th is done  so
late
that it becomes a penalty.  As a result, my best time and speed  (13.13 @
106.48) was achieved by running 3rd gear to 8500rpm, pushing in the  clutch
and
coasting through the trap.

So, back to the dyno.  Need to get that MAF dialed in.  I will  dyno and
tune
the engine this weekend to get it running right.  And then  I'll be back to
the strip on Oct 8th for another try.

All wasn't lost, however.  When you can run next to a new Z06 (I think  was
the designation) at still beat him by 4 or 5 carlengths in a heavy 4 door
sedan... you still feel pretty good, and generate a lot of curiosity in the
pits.
Stay tuned.
Dave
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