wastegate mod

[Robert Myers]

At 11:27 PM 11/23/00, DGraber460 at aol.com wrote:

>I have read the posts about it not helping without the ECU mod as well. I'm
>no expert, but my car has not hit the FP cut off. It may be that my car
>wasn't up to stock levels to begin with, but I don't think so.

If I remember correctly, the FP cut-off (stock) is set at 1.7 (1.9?) 
bar.  If the car is pulling only 1.4 bar then there is still some 
additional boost available without hitting the cut-off.  1.4 --> 1.7 gives 
another 0.3 bar which is good for perhaps another 20 - 30 (or possibly even 
40) more ponies, a SIGNIFICANT difference compared to 167 stock.  (If the 
cut-off is 1.9 bar then even more added power is available without an ECU mod.)

>The mod to the cap is merely drilling out the plug on the top of the cap.
>Under the plug was an allen screw that holds the spring perch. That screw is
>locked in very tight, and the cap is threaded to allow adjustment once the
>screw is freed up. I had to use a mill vise with plastic jaws to break loose
>the screw. The bolt is used only to lock the stock screw in place, now that
>the locktite has been eliminated.
>My understanding is that the stiffer (more pressure) the spring, the longer
>the wastegate stays closed, building boost faster.

Higher, not faster, but the point is well made.  There will be quite a 
perceived difference in the seat of the pants.

>The only gauge/meter I used was a Duty Cycle meter. It allows you to set the
>mixture, which if correct will give a DC reading (at idle) of around 50%. I
>did some trial and error (seat of the pants) empirical adjusting to balance
>between WOT and low end partial throttle response, and have not yet hit the
>dreaded FP cutoff.

Which feels like something akin to hitting a brick wall.  The engine simply 
turns off briefly - "Whoa, Nellie!"

>I have no idea how much more power I might have, but the biggest gain was
>that the car now has useable power in the 2-3k RPM range. It is _much_ better
>in traffic, and the boost gauge does show more boost on WOT. It would get a
>little anemic at +5k before, but now pulls much better to redline. My guess,
>since the gauge is notoriously inaccurate, is about 1.6 bar.

Which fits a 1.7 bar cut-off quite nicely.

>I'm sending this to the list also as to avail us of any necessary
>corrections, or other added details.
>It may be said it's not worth it, but it made big difference on my car.

An ECU mod will make an even greater difference.  It can turn that purring 
kitten into a snarling beast.  :-)  The WG mod is simple and cheap, though, 
and probably quite worthwhile if boosts levels on the unmodified engine are 
somewhat lower than the FP cut-off level.

>Feel free to ask for more details if anything is unclear.
>
>Dennis
>
>
>
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Bob
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  Robert L. Myers  rmyers at oak.total-web.net     Home 304-574-2372
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  '95 urS6  Cashmere Grey - der Wunderwagen    ICQ 22170244
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