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$8D Knock Attack/Recover rate

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Old Aug 25, 2007 | 12:28 PM
  #1  
JP86SS's Avatar
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From: Browns Town
Car: 86 Monte SS (730,$8D,G3,AP,4K,S_V4)
Engine: 406 Hyd Roller 236/242
Transmission: 700R4 HomeBrew, 2.4K stall
Axle/Gears: 3:73 Posi, 7.5 Soon to break
$8D Knock Attack/Recover rate

As I was working through items in my XDF, I noticed that the conversions for the two items were different and displayed values were magnitudes apart.
Both reference RPM as as the controlling value but...
(820E->8212)Knock attack rate = 0.0225 * X
(8213->8217)Knock recover rate = 1.953125 * X

Wanted to make the conversions so the values would be the same magnitude instead of the first one being a two decimal value while the other is in the hundreds. Checked through a couple of older files and found the same conversions.
Any guesses/reasons this was done the way it is?
TIA,
Jp
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Old Aug 25, 2007 | 12:50 PM
  #2  
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From: houston
Car: 83 POS monte carlo 2015 chevy P/U
Engine: 92 5.7 tpi 5.3
Transmission: 700r4 6L60E
Axle/Gears: 2.42 too high
Re: $8D Knock Attack/Recover rate

as we know, knock is bad & you want it to stop as fast as possible. i believe why the attack rate is more aggressive is once knock has started, it takes a little while for the chamber to cool off before timing can come back up without getting more knock. i think the slower recovery is better.
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Old Aug 25, 2007 | 01:16 PM
  #3  
JP86SS's Avatar
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From: Browns Town
Car: 86 Monte SS (730,$8D,G3,AP,4K,S_V4)
Engine: 406 Hyd Roller 236/242
Transmission: 700R4 HomeBrew, 2.4K stall
Axle/Gears: 3:73 Posi, 7.5 Soon to break
Re: $8D Knock Attack/Recover rate

Got all that, why would the calculation be so different for the same thing?
Just looks goofy to a user that one entry is done in "0.xx" and the other is "xxx.0" units.
Seems to be a good place to divide by 1K and have both items be the same scale.
Know what I mean?
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Old Aug 25, 2007 | 01:46 PM
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From: houston
Car: 83 POS monte carlo 2015 chevy P/U
Engine: 92 5.7 tpi 5.3
Transmission: 700r4 6L60E
Axle/Gears: 2.42 too high
Re: $8D Knock Attack/Recover rate

i see i misunderstood what you were asking you><me
maybe it goes back to the early 3-C systems with knock control?
it wouldn't surprise me if you understand this stuff better than what the guys who originally wrote it did back then.
if you can make a change & it still works right, i say do it.
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Old Aug 25, 2007 | 01:57 PM
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From: Chasing Electrons
Car: check
Engine: check
Transmission: check
Re: $8D Knock Attack/Recover rate

The knock attack is done in the spark minor loop, 80 times a second. The knock recovery or decay is done in a major loop, 10 times a second. Which is actually done 5 times a second as the minor loop counter is checked for which loop is being executed.

Hence the difference in conversion.

RBob.
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