just askin': final drives & gear ratios

[Peter Berrevoets]

This is from the S-Cars list, a little tongue-in-cheek perhaps, but
interesting enough...

(names removed to protect the innocent)
<snip>
> Last night at the Texas Motorplex a S4tt with a chip only ran a
> 13.192 @ 104.28mph.  I seem to remember someone saying that was not
possible...

Anything's possible.

Actually, I have made runs with my S6 in the mid 11's.  There are a
couple of tricks:

1. Put on some skinny slippery tires.  This lets the car generate
some serious tire slip, protecting the clutch but, more importantly,
allowing a 7000 rpm launch.  With AWD, you will hook up quickly
anyway, so the stickiness of the tires is not important.  I use
195/70 snows.

2. Install a 25 psi pressure relief valve in the inlet to vent
compressed air to atmosphere.  Also add in a exhaust side air/fuel
injector to drive the turbo hot side independently of the engine.
Play with the chip to avoid shutdown due to MAF confusion.  This
arrangement will allow the launch revs to be brought up to 7000, with
the throttle cracked, with the entire intake system upstream of the
throttle at 25psi.  Makes for great launches with NO turbo lag and
huge torque from the get-go.  Works great with the skinny tires.

3. Build a box around the intercooler and fill it with glycol.  Route
the lines from the air conditioner to cool the glycol to -20F before
each run

4 A Hurst shifter - a must-have for the quarter mile

5. A shorter diff ratio - something that gives about 130mph at
redline in 4th.  5th would be better but it is hard to find a real
Hurst for a 5 speed.  Just ignore 5th - it isn't part of the 1/4 mile
anyway.

6. Remove the rev limiter, in case your gear selection is wrong and
you need a few more rev's
Other than that, it is stock.
With these few changes, you too will have 1/4 mile bragging rights.

<end insert>

April 1st was the post date but....

;)

Peter Berrevoets
1990 200TQ
Toronto, Canada
http://frontpage.home.net/pjberr/


> >-----Original Message-----
> >From: quattro-admin at audifans.com
> >[mailto:quattro-admin at audifans.com]On
> >Behalf Of Chris Dyer
> >Sent: Tuesday, April 03, 2001 5:04 PM
> >To: quattro at audifans.com
> >Subject: just askin': final drives & gear ratios
> >
> >
> >The 0-60 thread got me thinkin' about "Hot Rod"
> >magazine-type discussions.
> >Specifically, final drive and/or gear ratio changes to
> >decrease 1/4 mile
> >times.  One might consider this for one's '87 5kcstq w/165k
> >mi.; IF one
> >could maintain relatively low rpms at highway speeds (3k
> >approx at 80mph)which
> >would mean also changing the individual gears I spose.
> >Anyone done this in
> >a quattro application?  On paper, it sounds like it could be
> >good.  Maybe
> >not a 4.11 final drive, but something in the 3.63 range maybe?
> >
> >(it also got me thinkin' cuz I went to the Dinan site and
> >that's one of the
> >performance goodies they offer to WMB's)
> >
> >tawk amongst yourselves, discuss.
> >_________________________________________________________________
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