I =could= do this, if there's no other way of finding out, but I think someone already has the data. I've seen graphs posted by one of the other AID/BTM users.

I can't remember the numbers, but as an engineer myself, I was impressed by one particular characteristic of the AID. The OEM module abruptly shifts in a fixed amount of ignition retard under boost; it senses the pressure threshold, then =click!=, retards the ignition X degrees. The AID provides a tapered boost/retard function, wherein more boost pressure gives a ramped-up retard of ignition. The result is better timing in all the boost regimes, from light boost to massive.

When I installed my AID I posted some long posts on the test procedures. I experimented with the timing from 18 to 22 degrees, and found the best results at 21. (Smooth, sustained, top of redzone boost, no knock.) It was fun going out and making repeated boost runs on a local freeway! The test pilot in me craves this stuff periodically.

If Kevin's still following this thread, I'll bet he can tell us where those AID advance/retard curves can be seen. If we can't find someone to post them, or a website reference to them, then I'll go out next week (I'm out of town this weekend) and try to plot vacuum/pressure versus timing with my MityVac and timing light to see what I can see. The Beastie is due for an oil change and tire rotation, so I'm going to have a "garage day" some time next week anyway. May as well play around while I'm getting dirty!

We might get more accurate results from someone who's done this experiment with better equipment than I have. I don't think the little gauge on my MityVac is calibrated for great precision. Also, it's good at drawing high vacuum, but not so great at pumping in pressure, so I don't know how well I'll be able to plot boost versus degrees of ignition retard with what I have.

- = M = -

• Vacuum Advance question, Jeff Cunningham, Wed, 14 Feb 2001 13:03:00
  • Re: Vacuum Advance question, Kevin K , Wed, 14 Feb 2001 21:59:12
    • I knew you'd know! :>, Monster, Thu, 15 Feb 2001 08:25:34
      • Monster, could you check..., KeithG, Thu, 15 Feb 2001 18:11:20
        • It's been done... Kevin???, Monster, Fri, 16 Feb 2001 09:22:47 <-- Viewing This Message
          • Re: It's been done... Kevin???, Kevin K , Fri, 16 Feb 2001 13:11:26
  • Re: Vacuum Advance source is before throttle..., JohnK, Wed, 14 Feb 2001 19:33:08
  • Re: Vacuum Advance question, Ari , Wed, 14 Feb 2001 16:12:44
    • One more thing..., Jeff Cunningham, Wed, 14 Feb 2001 17:02:40
      • and another thing..., Monster, Wed, 14 Feb 2001 19:10:52
      • no, no, no..., Monster, Wed, 14 Feb 2001 18:50:45

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