Cam Advancing - the Full Monty

[QSHIPQ@aol.com]

Those that paruse the archives, or have been here some time, should delete
this post.  The subject of Cam Advancing has been covered in depth here, but
as usual, *today* the archives aren't common reference material.

A couple of points on advancing camshafts.  The net effect of advancing the
cam is to open the intake valve sooner, which certainly helps on low end
torque.  Sometimes (details to follow) this is at a great expense to high end
horsepower, but to date, I have done probably 50 cam advances to 44 and Urq
10vt cars, and reversed maybe 10.  So, the majority (given the low 'n') find
the benefits of low end torque, outweigh the loss of high end HP.  

That said, the benefits are as follows.  The turbo spools up sooner, the
torque is seat of the pants noticeable, and really no other ill effects on
longevity, knock or even gas mileage (insert right foot exceptions).  I did
progressive-mod-testing on a late 89 10vtq (2.0bar) and found that the car
didn't come alive until the cam advance.

The downsides are as follows:  High end tapers off sooner.  

Also, my testing has shown that ALL audi 10vt cars do well with some cam
advance if using a stage II or higher computer.  The late 89> cars do the best
(the revised cam profile takes less away from the top, gives more at the
bottom), the more mods do the worse.  IOW, if you have exhaust, EM, IM, fuel,
IC, turbo mods, the cam advance of 1 tooth (~8 degrees), is too much.  I do
know with ALL the above mods, that less than a tooth still helps, btdoingthat.
For those of you interested, most of the vw adj cam gears work on the early
audi I5 (do remember that the sprocket changed design in 89> cars).  

1 tooth adv:
The loss at high end really doesn't have a big effect on either the 1/4 mile
numbers or the 0-60, the added low end (especially with the 3.89 gearsets)
offsets the flat top end.  I measure slightly less 1/4 mile times, and better
0-60 times (YMMV).  

Bottom line:
A mod worth exploring.  It costs nothing (I do the tooth pop in about 30 min
total drive to drive), and you might find that it suits your driving style
better with it.  For those that tried it and find it to be going in the wrong
direction, I would suggest buying an adj cam sprocket, and play some more.
You might find that this mod is worthy of serious consideration, I did, and
the measured numbers were better.  BTW, btdt on both the stock early, stock
late, and shrick cams in a variety of applications.  

HTH

Scott Justusson
'87 5ktqwRS2 +<1tooth
'86 5ktqw -0-
'84 Urq +<1tooth