Re: turbo cam in N/A 5K

[Gerard <gerard@poboxes.com>]

Hi!

Just want to add to this thread with some silly questions of my own.

When one swaps to a new cam what does one have to do to ignition timing?
I mean, if I switch to a better breathing cam in my 200t, say one of
the Schrick cams, then  obviously the air flow habits of the engine have
changed and one has to take into account the manner in which the
ignition needs to be changed. Would a company like Schrick (spelling??)
provide information on what timing (both cam and ignition) need to
be changed? Also, say for example the turbo boost levels have been
increased and the timing values have been changed and one then changes
to a better breathing cam then how does one determine how ignition
timing needs to be changed?

The reason I'm asking this is that I'm interested in some mods to my
200t. The current one on my mind is to increase the boost to 1.8 bar
from 1.4 bar by modifying the ECU. I'm clueless as to how the ignition
timing should be changed from stock when increasing the boost levels,
but I hear people saying things like "retard timing 0.5 degree per
pound of boost" (does this mean if I increase boost by 2 pounds from
stock that I can safely assume the correct timing value should then
be 1 degree of the stock ignition timing for a particular boost and
RPM match??). So if I can finally figure out the correct way to change
my ignition timing as I increase my boost and then later I opt for
a better cam then how will I know how to change my ignition timing?
Will I just leave it in stock form?

BTW, I'd really like to know from Audi ECU modifiers how they determine
the amount of timing retard to insert in the timing tables when
increasing their boost levels. All I've managed to figure out is that
I can retard the timing by 0.5 degrees for every extra pound of boost
I add. What I'm aiming at is not to leave the ignition retarding up the
the knock control mechanisms in the ECU, but to modify the tables to
provide the correct timing to start with. I heard one modifier had
increase boost pressure to the 1.8 bar max level and simply removed
a degree of timing off each of the entries in the timing tables in the
ECU. Any help on how timing needs changing when upping boost or changing
cam (both cam timing and ignition timing) will be very much appreciated.

And, no, I'm not doing this for profit, I'm just aiming at my car as
a pet project. (But all in the future ofcourse as my car seems to have
bad big-end bearings or tappets!)

Thanks. :)

G.
-- 
"a thousand miles from here, there is another person smiling"
1990 Turbo (200t)
name   : gerard van vught
tel    : +27-57-912 2658 (w) / 082 923 9609 (cell)
url    : http://homepages.acenet.co.za/gerard/
e-mail : gerard@poboxes.com  / han.solo@galaxycorp.com
         gerard@acenet.co.za / van_vught@frg.issi.co.za