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I have had excellent results with a Dawes MBC - - but NOT in the default use.
After researching several posts, I decided to install it as Beaudreau suggested: namely, using it in-line between the turbo and port "C" on the BCV. This is the port that measures boost and reports it to the APC. As I understand it, the APC monitors boost, and once it detects even a few pounds of boost, it begins to crack the wastegate, allowing some boost to escape. The result is that the moment the turbo begins to spool up, the wastegate lets some of that lovely boost bleed off. This is done in order to avoid a too-dramatic surge of acceleration.
Too-dramatic surges of acceleration, of course, is what WE all seek here on this board.
In this installation, the Dawes device is set so it will not let pressure reach the BCV until it reaches your preset level. This is set low enough that you are SURE you won't have any knock (mine's set at 8 lbs, a conservative setting). Once it reaches that preset, the Dawes device opens, pressure reaches the BCV and the APC begins monitoring boost with knock control operative and ready to prevent serious damage due to detonation (you hope).
The result, for me and apparently for others who have posted similar results, is a noticably quicker boost surge.
This is radically different than the standard configuration, which would eliminate knock control. I wasn't willing to go this way.
If the Dawes device is installed in-line in the "C" port as Beaudreau suggested (as I described above), the little relief port can be sealed. I used my teenage daughter's red nail polish. Looks very sporty, and everyone knows every red accessory adds a few extra horsepower.
The Dawes deluxe kit came with everything I could need to install the thing (except a miniature mechanic in a box, maybe). I used a ziptie to fasten the device right on top of one of the hoses where I could get at it if needed. (I hate vacuum connections I can't visually check and readily reach).
A final note: the Dawes device was just about the last performance mod I've put on the car. It did seem to bring everything together very nicely, but there was a lot of underlying work done to get the full benefit of the mods. But the result has been worth it: on a cool day it'll peg the boost needle (23 lbs) and it'll hold 15+ through the next shift point.
Jim Watts
The Stealthbomber: 87 SPG, Modestly Modified
Modified APC, open K&N, sport exhaust,
24 lb injectors, 3.0 fpr, SPG9 AID, Dawes device
(inline to “C” port on BCV), poly motor mounts,
stainless brake lines.
posted by 32.103.140...
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